|Table of Contents|
First use of hydrocyanic-acid gas against insects in stored products
Chemicals and other supplies
Proportion of chemicals
Estimating amounts of chemicals for fumigation of mills
Preparing the mill or other building for fumigation
Cleaning the mill
Method of "stringing" a building for fumigation
Process of fumigation
Possible dangers in use and general cautions
Summary of operations and precautions
Order of procedure in fumigation
CIri.*A NL'. 112.
1i 11 11 Tv^ -? I-9' I l i' di
-i-nited .tatW o Agriculture,
u 0 E ^BRA ^N TOM Ojjo N,
L. 0 ARIl'.rlli>[TijliDtlill and Chief of Bureau.
(CONTROL OFp THE: .MEI.TIE'i.iIANEAN IFL.OUR I MOTH BY
HYIIROCYA.NIc-A(u) GAS FVIMI(ATION.
Bly F. Il (iiTrr;N>K, Sc ID.,
jI h ur.r I'. i *r d "' "* i ,i lh !rt Iit'if stijUuflSltb
1NTRODF '( CTOlY.
I'ntil in .,liie" hici recent .i 1l,-m mills in th iih I'n ited States
wr'e litth troubled with iiijiili'i- insects. It is true that wevvils
and 0ihe"r grlilialiy pests were hiii..lil into thite nills w ith -'Iiiii. and
in tlhe ciUirl'. of time iliiii\ mills have becomeic infested 1viti flour
beetles. 1 B4,imiihiiil i, with the year 1S2, however, several (C'ali-
1 ~t. " ,,i L" [BS
i t. l"\S IH
Fin I -Me LpiruIpmin.ii flour i,iili (Fphet inkBtKmilla): a Moth;.
,am from Idle r-tng; m', la ; r 4 pup%; 4 i alMi taI i Lnen nI,
oflan a -d V .nlo .rL-,. I Mninrt'-nlair.- I author's s tlll u tittton
Fi -r M.i trrinean
fluur oth: Larva,
do7sal v:,w. (Iu-
thor't |lluatr ilion. )
fornia mills 111'le-iii. infested 1,v the 1IIhliiirraneanI flour moth
(/-./tIIt' k/uehnlla Zell. ), which has been aptly .!,lid "the scourge
4f the fltir tn1il and the "wiiiztl .riie y )itiL'e" Ai first its i,' ..
in this country was slo\i, but i less than a decade it had become
recognized as a i, st serious pS.Il in many Sint,-. and at the present
lime it is known to occur inl prictiailly all of our piin, il1il iiliii,,
centers, ad in in',( ,,f our Stit,;, from the .ATliiiiir to the Pacific
anl, from ('nailaa to Mrhxio..
Si hi'tla [,', I,- 4i Tril, i iiri. t i iM.'. r i ru7 !..n.>r- ,,, 4f i. r,-
259)-- Car II112--- I -'---I "
. . . . I
Des7criptive.-The adult insect is a phycitid moth with a wing
expanse of a little less than an inch; the fore-wings are pale leaden
gray, with transverse black markings of the pattern shown in the
accompanying illustration (fig. 1, a); the hind-wings are dirty
whitish, semitransparent, and with a darker border. The larva or
caterpillar, illustrated at figure 1, c, e, and at figure 2, is whitish with
minute black d(lots, and sparsely hairy. When full grown it measures'
about one-half an inch or a little longer (12.5-17.5 mm.). The
chlrysalis, shown at figure 1, d, is reddish brown.
Distribution.-Until the year 1877, when the moth was discovered
in a flour mill in Germany, this insect was comparatively unknown.
Later it invaded Belgium and Holland, and in 1SS6 appeared in
England. Three years afterwards it made its appearance in destruc-
tive numbers in Canada. In 1892 it was reported injurious in mills
in California, and in 1895 in New York and Pennsylvania.
From that time forward until 1904 the dissemination of the species
was comparatively slow. In 1898 it had reached Minnesota, the
next year Wiscorinin: in 1900 it had greatly increased in Minnesota;
two years later it invaded Michigan, and by 1904 it was reported in
several other States, including Indiana, Illinois, Montana, Colorado,
Ohio, and Iowa. In later times, each year has witnessed a similar
increase in distribution, until now, in 1910, this flour moth is attract-
ing more attention than any insect that ever infested mills or other
buildings where cereals are stored; indeed, it is almost the sole topic
of complaint of millers at the present writing, correspondence in
regard to weevils and flour beetles, which was at one time heavy,
having fallen off very noticeably.
Ravages and habits.-The caterpillars form cylindrical silken tubes
in which they feed, and it is largely due to their habit of web spinning
that they are so injurious where they obtain a foothold. Upon
attaining full growth the caterpillar leaves its original silken domi-
cile and forms a new web, which becomes a cocoon, in which it
undergoes transformations to pupa and to imago. While searching
for a place for transformation the insect is most troublesome. The
infested flour becomes felted together and lumpy, the machinery
becomes clogged, necessitating frequent and prolonged stoppage, and
resulting in a short time, in large establishments, in the loss of thou-
sands of dollars. A sample of matted flour is illustrated in figure 3,
from a photograph by Mr. C. H. Popenoe.
As to tlhe losses caused directly and indirectly by this insect it has
been difficult to obtain estimates, the lowest being between $100
and $200 to a mill of 1,000 barrels capacity. The average loss due
to closing down the mill and cost of treatment seems to be not far
from $5)00 for each fumigation, "to say nothing of the Ioss to busi-
ness," according to one Kansas milling firm. An estimate of $1,000
for two friiii.iii-imi. can not be far from ri,1'll, i lf 1 ,,-i i 11< I(ers sti-
iin t _'.I IID), while still othersI ow' i rs f ( iir,_,. mills laim it t, ho
$5,0UU a year. Oio prominent miller states thilat, a-ido frmu the c(,t
FIG. 3.- Matted flouLLr ho.wini !he work of the Medit erraean flour moth. rin.i )
of ftiniii.',iiii, the loss due to .tii[i.,e while l(,iIii'. is il, ;il.iiliiil,
and expresses the opiniiin that some restrictions should be iiii,,-.',l
on millers who do not clean and fumnigile their mills.
[Cir 1 1.]
Although the larva prefers flour or meal, it wiil attack grain when
the former are not available, and it flourishes also on bran and pre-
pared cereal foods, including buckwheat, grits, and crackers. It lives
also in the nests of bumblebees and in the hives of the honey bee.
FI.-lT USE OF I1YDROCYANIC-ACID GAS AGAINST INSECTS IN STORED
The use of liydrocvanic-acid gas as a remedy for insects in mills
and other inclosures whore grainl, flour, and similar products are
stored was first .ugzge.stedil by the late W. G. Johnson in the American
Miller for Mhirch, J1%9.'%, the incentive for its cnmphloynient living been
an invasion of cockroaches in a mill in 'Nortlh Carolina.
The first test of this method as a IM-,.IS of d(st roving insects in
-tored products was p),.ballly that made by the writer the same year.a
Additional experiments were soon afterwards made in conjunction
with Mr. Pratt and the cost and the advantages and disadvantages
carefully weiglheil, with the resulting conclusion that since hydrocy-
anic-acid gas is infinitely more dangerous to human life than bisulphid
of carbon, as well as more expensive, its employment, as a fumigant for
ordinary insects injurious to stored products was less desirable. On
this account no publication was made of the results nor was it, until
recently, recommended to the numerous ipersons who inquired for
remedies for mill pests. Soon after this first experiment a test to
determine the availability of this gas against the Angoumnois grain
moth was made on a larger scale but with very imperfect success.6
aMarch 5, 1898, the writer, with Mr. F. C. Pratt, then working under his direc-
tion, fumigated a lot of dried grain infested by the rice weevil (('alandra oryza L.)
and a leguminous seed affected by a Bruchus or seed weevil, the material being placed
in a moderately tight fumigating box. The cyanid of potash was purchased in open
market and was used at the rate of 2 ounces to each 100 cubic feet. A quantity of
acid slightly in excess of the salt was employed with twice that amount of water.
The experiment began at 4 p. m. Saturday and was conducted in a building in which
the temperature was usually from 70 to 76 F. The following Monday morning at
7.30, when the door was opened for airing, no odor was perceptible, and only a very
slight trace of gas could be detected a half hour later when the box lid was removed.
As a result all the seed weevils (Bruchus) loose in bags were found dead and all of
the rice weevil, except a very few individuals, which revived after a few hours-
less than 0.1 per cent-were killed.
b A lot of paddy or unhulled rice infested by this moth was desired to be fumigated
and was placed in what appeared to be a nearly air-tight inclosure, a room specially
prepared for the purpose. The cyanid was prepared in the usual way and was used
at a strength of about 1 ounce to 100 cubic feet, but after the fumigation the insects
were seen to be flying freely about the fumigating room. See Bureau of Entomology
'ir. No. 46, entitled, "Hydrocyanic-acid Gas azain-t Household Insectq," by L. 0.
Howard, first issued in 1902, revised edition February 20, 1907. Note what is said
in the footnote on page 2.
D 1 111,-,' 1''1'11 mills wer\% fore ,,r-i..,ll id in liennsylvania and )hi o, undr
the directions of I',If .... r .. 'l4it i.. with satifavtory '..,ll*. and con-
1in.ii I in later y ears l v and unI 'r lthe lirectin <)f professor .1 .liii., i s
w e ll a s b y P "I, ,,f .. \ a s h b ,,n nL. ,S ta t e ( "l ,inl,," -,.'i -l o f M, lim r,- ,,ta P ro f+d .
II. .\ Surface, State ,.i.At. -i- C of Penn-yh ania, mind ti her SNate
,,i1 n 'iIl- I htitie course of time I, i.I 'anit-a(cil _',i' has conlli to h''
ri.',, ,i/,., uas tli- hest f[ ii ._'..1 il for the .I 'li ernoiain flour m(ot.l It
is i',jil l' valualh' .,_. irl I related m11t, 1s1 found in m ills, Iuit i Ie-ss
tl',(.t i I. in dest I' il i hlour eethes amn M _'i.ii \i',.,.il-. a:il ev(n in
the destrtctioin 4) the .\ i ll ',ll 'i i- *_'i.in in ithi in (corn. Iili., it is
,11 d.'iiv *" 11 reonii tmendetd for anyv ,f 4he I hatter pests.
FIronm ihat suhle(|ii(ntly Iha" been hlarnet i f ti his inet ldiI failiire
in soie cases was utdm ulhte('lh due to iimpire polttassium (.,iwiiil alndt
to fZiltv ijl' lli, ii, o(f thie ll oce-s, sin- ce tlie f'iiui.'., liII,.. vessels wvere
rather iiiuiill for the 11l,1p'-' and Iermitted a comsiderahle '-,iliti-,
over at the tlop. Much residue also remained;: in other i.ii!- tlie
potassium vll .'iil was pro)al'l too \1,it pr ii.(()I) no s'r, -ii,',. than
.) a) to i Iper( c lnt i,,, 1.as was also thlie sulphuric acid. which was t not
used in i icll',il quantity to produce a perfect '_':i-. a considerable
,nimiint of ,'.\ ndln i.uiiiniiii.n_. unaffected as solid residue in tlhe enerat-
ill-, vessel. It stems also probable that tile cvanid was broken into
too fine particles, h)ut this detail can not noTw be renimibered.
O() in,., to these failures as %II as to those of other tests whimh were
aft~,u, ii[ i made, the suspicion arose that -nwtiii.liiin: was \ i, iii: with
the iii.rr,',iert -. \ sample of the cyanidl usetl was sulbmittel to
the Bureau of ( \i,.ii-irv and treated \1with -,iilphiir idI. with tihe
ri'-ilk that only .'1 50 per cent (f the amount of hyidr evanic-ac('id
,'it- demanded by theory was found. Analysis showed 51.7 Ii per
cent potassium ,.in iid. 2.()7 per cent sodium c anidti, and 'l'2 pier
cent potassiumi carbonate, the remainder i ,ii-rir- of sotlium chlo-
rid or common salt antl impurities. It. will he noticed that this
i' .nid as little more than half as -~liz.'- as dIemandedl lir per-
fe't work; hence, what iips,':ired to be a intiii_':,i, at the rate of
:i1 ounces tIo 1 in" cublic feet was in reality mnlv about tI ounces.
An instaiwe f : oiii ii in w ith immure uyanid potash .-h uhlI h1- cited, I urine
5.,lr. nil. r 'I)I, th > rl.rit r, with IM r 1'rr. untd-rt
to I fcubit feet f space, hih I -. !r. ..! many beet lh Two we, kv la, ir, hki v I er,
the beerth had aIm I ac Itiiulated in number, 1 h1 'iI I t hat Ineit her larva+ tior pupar
had bet-n kill,..l t' any (,xtlcnt. Then 3 )nices *, ..,,rl w irr t us, with a .r'll loic(r
textpwur, a tota I 1 ,nt I.ally frty- twiI h .ur:, I '. killhI v, i I li ra -, which
r. .[ 1 from the urnirtui the I, r .. ;|.l seat oif infestati i. -;, li.' ;. ,i irp Itlt -ere
also .11, f ,I i but man'1 were fIr .1. il. not kill. < L 1. r' ,1 ii the t rI' - r k w r ot
de-tryd Iw I the inects otitinu ,d ti inf-t the Iu-t-s, with tt, reiIt hat bf ireT a
thirdL fumiItion could be -i nIn tIhe furniture wa' frisprre d of.
lI"r iprticulars see pg e-', ,. Il.iil fi., lIur. laST I. S. leptI \-r, IIrI)I
It should not be imagined that because this method is of value
against the Mediterranean flour moth and related insects, and soft-
bodied species like psocids or book-lice, which also occur in mills,
that it is a sovereign remedy for other insects in mills and other
inclosures. Quite the contrary; it has been found only l)artially
effective and therefore unsatisfactory when used against, grain
weevils, flour beetles, and other hard-bodied insects, and the pre-
paratory stages of the Angumoiniis grain moth, although effective
in killing the adults of the latter. Indeed, not until very recent
years has its use become generally recommended for the flour moth.
Mr. C. H. Popenoe, working under the writer's direction, in fumi-
gating primarily for the flour moth, succeeded in killing many of the
confused flour beetle (Tribolium confusum Duv.) in two application,
at 4 ounces to 1,000 cubic feet. A larger percentage was destroyed
by one application at the rate of 8 ounces, and so on up. Mr. D. K.
McMillhi n had similar g,,, d success with 10 ounces.
In pamphlets published in 1904 Prof. F. L. Washburn has rec-
ommended hydrocyanic-acid gas for the treatment of the flob-
moth, stating the advantages of this treatment and giving details
as to the penetrating power of the gas and other matters.a
As an instance of the successful use of hydrocyanic-acid gas, the
experience of a Kentucky milling firm that was advised to use this
method of fumigation may be briefly narrated.
In the city where this firm is located the species had been present
in their mill four years, yet a few months prior to hearing from them
the writer did not know of the insects' occurrence in that State. It
had been introduced in second-hand machinery. Bisulphid of carbon
had been used by them previous to their correspondence with the
writer and was described as "no good except for weevils in stored
grain." It had been (emploelcd at the rate of 300 pounds to 62,400
cubic feet of air space, or about 5 pounds to 1,000 cubic feet-fully
twice as strong as necessary in an ordinary mill. Afterwards, by the
writer's advice, hydrocyanic-acid gas was employed and the follow-
ing report was made, August 24, 1909:
Saturday, July 24, 1909, our mill was finmig.itled with hydrocyanic-acid gas, using
18 4-gallon jars, each (h.arL,.i with 3 pounds of cyanid of potassium, 44 pounds of
sulphuric acid, and 7 pounds of water. We killed moths and their eggs, worms and
bugs of all kinds, w:u-I,-. mud-daubers, spiders, bats, rats, and mice, and also English
sparrows perched outside on the roof. It has just been one month since we fu migated,
and we see no more as yet. There is no sense in a miller being pestered with ihe
flour moth. H)l dn.y.jnir-icid gas will kill the moth and the eggs.
Our correspondents also wrote that in their opinion it would be
(difficult to operate any mill infested with the flour moth without
a Ninth Annual Report .u;tcar Eii,,',li-,i-'t of Minnesota, pp. 31-36, 1904; Special
Report Si.tu Est itavl,,yi-t of Minnesota, February 29, 1904.
ftumiati ,niI. Ias the ('ost of -iI It till._ ,I,- 1 %'*i.lir.' m achinery, t -c..
U 0uhil destroy t het profit. In this latter fIilIIi_',:tiI iI. 5 I p [udIs-
LcViniil of potash were iiIi. equivalent tI ) I ) ounces to l,i ii cubic
feet, or about one-third mure than necessary if the Iilil.i.-. wNs tiht
atI the iii.,redii.l, kno wn to Ihe pure.
S I'MMI I"V Y 1" VALUE OF TIIE IIYI)()CYA'NIC-ACII) 1 AS METIIOD.
Tile special qualities of hy Iroc.yanic-acid III': and some f tilte ad-
vanta-ge- which it possesses over other insecticides (as w ell as its
ili.ailv,%ii .1 -<) as a fhJi,.,Iii! for mills and other 1. 'i, ili:'1 infested
b% insects may be 1iri,.llv summarized as follows:
1. It is generated w without tie aid of fire, in which respect there
is a distinct ad\ iilI'pe in its use in preference to sulphur Iriiiii,,;-
tion, unless the ('la-vti process is employed.
-2. It 1is practi,.ally ii, iiiiillitiiiiiu ill' and nonexplosive in a l:ir.i,
confined space when generated ai ,'.,,',li,,. to methods now in practice.
3. It is p,..ililh, therefore, to use this method of fiiiiii-:jliiii where
with the 'mIli\, .Nuint of eithlier l)isul)hiid of carbon or sulphur a con-
flirt within insurance companies iii.lil, occur.
-1 It is not iti(iriiiii- to cereals or other dried products in .i',,',
either fkr food or ft',r seed, in which respect it is superior to sulphur,
whichl d -tros the .'.rrriiiii liflL; qualities- of seeds as \,ell as plant
5. FmiiiiiiL.i, in may be ei'plo,, ,vl at i:i, iv ir'. iilit or day, but
preferably in a moderately warm temperature and on a calmi day
4I. In a -.very short time after ventilation of the treated premises
the characteristic "peach-pit" odor of the ,:I-,. entirely disappears
andl. 1prup10rl uV.1'l, no solid residue remains in the generator.
7. 11\ulri'vaiiii,- i a 7., is li,'liir than air and has considerable
j)ti,'1 ir:1It i,. power-not sio .',:I', however, as possessed by sulphur
\il.re forced into b!uillinii. and other r inclosures by means of the
dead.Nly atmosphere, and thus used destroys mos-t -t.,. of the flour
moth and some other insects. It is still more deadly at a much
shoritr exposure to man and other iniwimuinl-. i,-Itliidi, domestic
animals, nrat, mice, and other verrITliin. than to mill insects.
1'. It is the most powerful p1iismi.', in common I iie, which fact leiii-:
frilly re<'-,iizi/.edI, human 1bvei,1; are not readily temIpted to run unnec-
essilrv risks ,of exposure to its Ile;,IIv fumes.
10. TIhe process is comparatively inexpensive under conditions
which permit of )buillinii--s 1,.-iii,,l made nearly v. li.i.lil, efper..i.,iv
when a complete exposun-e of between 24 and .;i; hours can be
CHEMICALS AND OTHER SUPPLIES.
In the fumigation of mills, warehouses, elevators, and other struc-
tures and inclosures infested by insects, especially the Mediterranean
flour moth and some other soft-bodied insects, in stored cereals, with
hydrocyanic-acid gas two chemicals are used, both poisonous and
dlingeroils to handle. They are cyanide of potassium, called also
potassium cy'anid and cyanid of potash, of a high grade or chemically
pure (9 Is-9i per cent), concentrated sulphuric acid having a specific
gravity of about 1.83 or 1.84 (equivalent to 6t'` Bauin6i, and water.
The standard commercial sulphuric acid will answer.
(yi,;d of potash (KCN or KCy), the first ingredient, is a white
crystalline salt, permanent in dry air, but rapidly decomposable or
deliquescent in a moist atmosphere, when it gives off an odor of
hylixroyani, or prussic acid. It is readily soluble in water, has a
bitter taste, and is extremely poisonous.
Sulphuric acid (112S04), the chemical used in liberating the gas, is
so well known as scarcely to require description at this point. It
might be well, however, to state that it is known c.,mrnercially also
as oil of vitriol or simply "vitriol," and is a dense, oily-looking fluid,
colorless when pure, having when concentrated a specific gravity of
about 1.8, and containing about 90 per cent HSO,. It is nearly
twice as heavy as water, and in action it is powerful, being corrosive
to both animal and vegetable substances.
IHydrocyanic acid (HCN or HCv), the resultant gas liberated by
combining cyanid of potash and sulphuric acid, is one of the most
energetic poisons known to science. A single dr(o) 4f the pure acid
placed inside of the eye causes instant death. When taken internally
it causes paralysis of the heart, of the respiratory center, and of the
vasomotor region of the medulla. The immediate cause (of death in
most cases is due to obstruction of the respiration or to stoppage of
the heart's action.
The purity of the cyanid of potash and sulphuric acid to the
degre(,e indicated above is essential to the success of fumigation,
and efforts should be made to obtain these chemicals through thor-
oughly reliable firms, and if there is any doubt a- to their strength
they should be submitted to analysis. Many of the disappointments
and failures in riiniigartion have come from the employment of impure
cyanid of potash or acid below the standard .trength. These two
agents are, however, now in such common use for fumigation pur-
poses that with ordinary care in their purchase there is little risk in
I dr. 112]
11:1; >l'i>lll a \ l | III 11K.% \ .Il .
T h(e livilnl '\iii ir-, ril ..'.ilii, i rilill'il I\ b '' niliiinlia ,ii "I' ir" iial
of pljtitsli inl sI lphlilrit.' inl iII w.itur. l'lic' lliot -r'-,iiiiiiuiil iii-ul
eflficienit 1i4'O ilu1 ti ii it) ti i if t iI -. t II. dlI'ilkj i rI-,l Olitt l ii ric' I iil I ll ri' i-.dli
investigation of thie su.litj',' lv lilt B1lur'Ltl 4 EnItilicl0'_' i in i' (ipt'Fi-
ti ti wit lih lLitiir l' i of ('lt'iien-'trl i l' l)t';eiirlil'tit ,,i .4'ri'iillul ',f',
is obtaiinl'Il iy tIlle follwili"r p eolpoitioii i-:"
ili l I a. i ll t i 1!i' i, r t ,i \i\ .i',_.' l . I IIlla ,' ;i\ ir- ilji n -
'oiiniuiit rial -iil|ahiiir ii i a it I t I i--lr.t-iir .... . I Illiial 4iia a.
Walt'er, b" nia'W ur'... I tlniil ,inn -
This formuln iila ii'e'-. -,ii,'wliiil fr'i0 n -. i t, t1ii ll'r f',riiii:lii-s iI u-'1
in m ill ftinilgatti1.' Aniv iiililii iiili ti ,r t ihrlei' ii.tr'e.lint'llt-i will
produce gls, 2tit1l Ih'llI 'e iil' tline (if '.e('v'rl' l J'e'iri11iit. wlii ll' l. i\'< I i 'll
recomni de n nl ati iiil re iI ii-t will yi h lil more e' II" s -; iit-I' ,iIIor'I
results, hut tlit' greilt'-t '',iioiit i: in m ttrierl,- will it Iiiiixilmii ginn.
proiductioiin is sevurei tl llowil)i tlile ilt)v< proportionli-. I l 11li14
forniull tlie nrtiI and wlter art .lighili" in x'T-- l' tll- PXi'I i 'lienii,'ii
needs, but it is e...enilial tlint ill lthe v niil slill lit' b mmii\rtelil i.ii,1
that there he sufci6ent wteilr pre. eni It i mai 1iiitii .i rutiploetlv
liquid residue. The iIue (if ac-,s Waiter, e. g., two puirt-. iaiiv Hiiu-C iL
solid resitilue, itlie Ilto itlisslveil potnlisiuil .Sullpsilte, ilth 1) '-in rolurl,
resulting from lie rt h li. n li iy ihli hic I ylro'vnnic-aicid g< i-. proIdue.etl,
aSee R S. Woclu,r. Ilul .N\ .'*. lur Ent., L'. S Dltj. ACtr., p. 3, .lune 11, ili'i
blThe formula (I: I.31 abi a' qua i il, il nay ,Io-k euit di-'l inc I'ErTin alIar aiii.. whi'h
have b en in OmiCwhi tl ae-ine'ral L .a lb nmiller-. iumig-lati4), andl ia hi'r'-. lii1 I ll- dil'ffr-
nle i. ve'n" Plight and ii man i e lv.iai,'
the amount 4l iidl anli w ti.er in,-h.lili in aria t i14 (lifquidJ inia.-'ur ) thin e. anilI :aii'I
tine-half mot', water lhian ai'ilI Irl 'ii e 'Thinla't'r i a ra'ini 21) b% 31) b.v I) fi.tI
rquire' 53 ouiniu- b% w 'ivhil, oif (-'aniil. SO iiiunr''-, liquidiil rn'a.-ur', -ulphuric ai'i,.
and 120 ouinC' -. liiini-l l -'lurr. u.itr'T .\ri (ri'in.ii.ll i jll i .-el I i" J hrii-uina, th-
.ulphuric ai'Il Ul liaihinal n lili.i.ilrt. lait l.aI. 'r .a iiiara' i
sub. tainially t-- ilIa- w i- u-iula-itiaii l t, ii-i lalta-If r iil.-
'.211iiiln ,l']maI.f 'i lI r ,,r nt illur 1I\ wIiin' l I ma1ili a.. **arm inI ai-
tarnn'i' r' .il -iil hiirim .ui iat i'.i Ja'r ''lit pirrn .
I,\ ..'tii .. .. ... .. . ................... .... I iinji -.. ,iir iliiaim -
al r .. ... ... .. 2. .iiI ,laa l la .a. .r
ILill, i .1 1 a ll laianlpl-
In ImiliT a fii| 'la th i a rtiiill.i I.-l-I aii ,rm.-I -Illl-il11liz tiQ 111. 4 ,nli[illl.m1ii al ,1 the l lrt i 1n %
weight i',r 17 aan][it.l liain I' m L.-ii.t.ir ... ii-'d ili riLia',r I.,rm ll -- T ihu-, while ihe
mivoirdiiplaii finnula rnlaii, ril'arl% the' .:-aunt, iwnw- lia' rth eaila l'lill w-i'.L'ht 1
thear'id, iht' rhminl' l rTeaciii i-a alim-c identical with the frmula. I 1 :1, whirh xwie
Thertie-icaIlly the differrenr- in aaid hegwee'n the' twi inrmnila.-i i- $l .-oiL'ht thait in
fum igatlinig mill-, the re''lJIt..- r .i,' aitrt l anl iial In lnia a .",' th'r ln iii i.hl l" -liizhl
ac id dffi, 'vir r ii'-lllll, a in a i.ri...,l, .,I al lal Iia. IiIhl .lllii ,llhi .,I ''.l- a I,,1l ,.l
2' 9) CI'l ir 112 I ll 2
ti I this bolizlifving or "freezing" of the residue may prevent com-
plete development of thle gas, as has been demonstrated.
Much recent work by experts and agents of this Bureau has denm-
onstrated that for ordinary well-constructed mills or granaries good
results may be anticipated by the use of 10 ounces of cyanid of pot-
as1h and corresponding amounts (if the other ingredients to 1,000
cUbit' feet of air space. This strength, therefore, may be taken as
tlie standard for mill and granary fumigation.
II' mills could be made practically air-tight, and some are nearly
so, undoubtedly a considerably smaller amount of cyanid to each
1.o00 cubic feet would give equally good results,a but the miller will
Hardly be willing to risk success by a slight economy in cyanid and
,cid, in view of the money loss due to "shut downs" incidental to
In very l',selv constructed or more or less open frame buildings,
or where only a short exposure is permissible, it is practically impos-
sible to successfully fumigate for most insects affecting stored prod-
ucts: but sometimes, by increasing the amount of cvanid to double
the quantity normally employed, fair results may be obtained.
Good results can not be expected with an exposure of less than
163 or IS hours, while a period of front 24 to, 36 hours is preferable.
ESTIMATING AMOUNTS OF CHEMICALS FOR FUMIGATION OF MILLS.
The first preliminary to the fumigation of a mill or granary is the
linking of an accurate estimate of the amount of chemicals required
for tlihe different stories of the building. It is desirable to make the
amputationon of space for each floor separately and to prepare a table
for the guidance of the operators indicating the number of generators
and thle amount of chemicals to be distributed on each floor. Inside
measurements should be taken, and thle height of each story should
be carefully measured as well as the floor space.
Under ordinary conditions it is best to generate the gas at the
standard rate on each floor of the building. The first table which
follows illustrates the normal proportions for each floor. These
tables are submitted as indications of a convenient method to be
followed in making the computations andI tabular statement. In
vit'w of the fact, however, that the gas is lighter than air and rises,
it may be desirable in the case of buildings which have many open-
ints from one floor to another, which can not be easily sealed or
stoppedl up, to develop the greatest amount of gas in the basement,
a Mr. C. H. Popenoe, working under the in-truclions of the writer in the vicinity
of the District of Columbia, and Mr. D. K. McMillIn, itfumigatiing uni-r the writer's.
directions in Kansas, have met Nwilh success with lI.wer strengths in fumigating nearly
air-tight mills and other structures.
[ ir. 11-1
ft h 11D it I ht i10.l'l II'Llf iLll ) 11-1 1iT ,11 .i> ii ',I Ii, -iii 1 1' l ii'_ Ii 'iii ~ 11i1il1 l nlli
I 11 l tl 11 ll l I't l ill11 I I n l ll ll '11 li r I 1 I , I t 1i i\ I \ r 1 I I I l l' ;I I, i tIi
uu( IuIiHI I f F\lt 'lltit l I I I' 'l ii' l' T fI 11 111. I' i I I it If .' Ti 1t' jIi3- |||
k in ri', illii,. lrnal i l 1,\ i l ii- i t. -1 i- : I i I .l
As 1 l1nIlliI1 t: Illl I I l I' l l It I l:; I I 4 :1 l i' I III ,II I I ii i, t i,1 I _'i 'l II H i I Ilrl'
p '4 f I 1 i,1)1r i I Im -I ll T.'l l ,,ll- i ,f I-' It l itt-: a I ll li 2t.tll -
Irl'iltii'i' l nlrcn l ilii'_ i" t, Ilr *.. n r *i;, i,, i ,ll',. ',,,lI, I* l..
l '\'lll|,l ,'1 l, .l-ll I ...,ll .I .d i l'.- I I ,] h-
I ii'l I ir il ,. 1ii- 1%1il f
W 1111 4 lilt I ll-ilt l 'v' -. I ll .I I I l. I '-- TI I \'ii ill \ ;-i '!ll lIlt '.l_ iii i I *i 'll. l,1
\.V ll, ||il n il nII 'r l lI\- u+ ,l n,, |l lll -lli .',nil,' Illlll ll i,, l ,,f Inl -l '~- x Il il, I, ', l l. l ,, u l-
2111.11 p IiiI in I '- nII o f u Ill," '\ i .i Ii -:Il
W,,h ihe it i-. ,rs-slltllill lr, -.ll,',,-.- I' ll~ r t il ,.r ,i ~lh ,',ltlI l~l~l- ,,f ,'|H ll fll,,,r
n -e tl ', rrl it ( .]\ ', tlll)ii i l. 11 I ,I I' 'hl I I i ll I' lli I ll l', i,,.fl t 1 I f'I
tit t ll l "' n f i t V i fr i ll l '- i- 1 If ll', -I I i "-.i tll llll-,l lr,' i t I'lI r Til l' J i ll I -
In ,'tl i f lil>t 1 ll1"11 ,11 ', "'IIH r ',, I i, 1 1 'ir ,,II- ,,I" Ii J... nr ,I"l ,I ll| \
|lil l t] ," hIII- ,m-, |i l (- I I |,'l,,,I I I I' ,, ? \ ,l\ -, i r .I-,,I r',n -'I i
h v r. I t v l i t'elr l lI,-. ].i i, i i. tl l i l i. i r ,' -i l iI i | i i i' I :1 11 Ill ,
lltl f Tin t lt I- ihh [hi' .s lji ;ii ^i\i illflt i 2 in )rhI!'. uri in.\ r.. i^.i 'Ii .11 ".I
\I'h r 1 Il l l I .1' r1 11 It i, 1 1 11 l .llt \ I'l 'i I II 1 2, I[ I l,
Illf ltih Um ',L illillllI t ll:.. I ,lll 'r I11,H -I lln '-- ll llx I"'. Iirll Ii I ll,, jml '.'-
nient (i f t] w i tll ,'r ill<>(r add |I l l li l I ll 'I ll; I ll ll Ir ,I- 10 I C -;I"- Ill\ Tiln- .
c. om'(l ]lis t,,l bY v c iiplI,, i11'. 1.-t ,':1 1i 1 .111 11 1 '.,.Vr I, i1ii]1-41111r"I'l l1 o
n r'1l,-hl "f Ill 'n l' Il" ', ll t%\ lI' I ll. I i, llill ll ,1 Tl' r ll 'li-'ll ',ri.d ll h','
am ouintt t ts 14 t' 1 lf,-4 l 'Ir.l" ,ill 'lr -,ill nI n i' l,,,.- of I -\ nrtl,'T,',l l i ili,._'-,
1,11111 be calculated ll fliv ;tlv..1.ili : l [llll .
T lhe' billow ingL' tlllillII ,r -I t.l i t-. ,r, -1lalIiml 1 *l- I I ~- .IlI |- HI I li.m l-
p l tint n tlie C.,lirt p o, |)I )i Iliill,.: I',,1 l l[. l ,,l r;II 1'll I T .I..- ;I i .'ll 1 I )iN )
ba,',rel.-s (1Ia Il" v I rii I i(t Il .' "
T he 2im ou it. I" i cI ii, li, il- l'>ta,. -i -,Il fI ,r :i .1 'I\ v i. b ilibliil,.-_ --I 'itlic.,
+ni'hlosi~i' ii]r<, its ,lirr 't p i[',, l,,,t +,,i t,, Titr ,I,"r 'rc ,r tif .. i IL ,|,.." i,, \\ h i.]i
it in aev l~e ( ln.., l ( )\\ in.,_. i, It,, ,_ l i ..L';II \ ..,ri..il'i]i \ ,,f iiil'l~iii.:-. ;itl.|
lm) ,'t th tr if it- r t' I r'l- tI-'ll' Ii ir '~. Pit I'.,1 1, ,4 I,, 1ii i il',,f'n -t rI' III...l
tra Inh it rN-r-lr.
p a rtsI I rI .If IZ l IX., l~ ,., ssr ']-i I. I l II l 1 11 I 11 m Ir ,,, Iv h ,~ h ,I, + 1 ,'
A an-, in i p .e x I \\1\ 'i-i- n it l' ,=a I i .l i. lil 1 1, 1 it -1 11-1...|
hy'lriifc anii -at ill -zaj at o r.11.ir i 4^ lit-' i r 'i*' in l!'rr l i i* .1 i i i-*r *
1:! ,) i in 'e i' l I 1.. w)l i i, n 1 i ir l .. IP, fth .1 lI ',r i % Ili. lI, i . im, I i. .II.,, .,, ,n
nii-.-,I, al-i" h -,, h u % --ry v ih i i-,. 1'% t1 hi r, .1 1l .. i tr -r...- %%., I| ... . I'. I I tl. I Il 1, ..
Io The i ,rni hlu-i,,ln. ll % 1h l, 11 ni,,l ri,,ll, r-I 1 "1 r- r ,r .i..i n, Iir I h 0r l,. ..'.'- ..r. -1 1..l.i
killed bl y ihi, III- Ir ,ilhc.r n w lh.-l' .I.r III1 1... L 1 11,11 --I %'r.. .... r .-.1 -hi.,n hi lm 1 -
ever, has s.tl fP ilie ( I t IIl- rl, I l IL m .i t-'-," i'Iiri'"...L ',il I i-r itr .Iii,, ,. P'il l
m ill pr i,,,I t in ,, l, h ll ,li r I t, i '_..'- ,. rl ~- ., hi, li, h, i, r I Il,.1 i.. d ,* I|
P II ."h Il he h,.r !.Ij ,, l i. i, dIl r ..-. in. r.,I .. , r'. .i i.. ,.i, .. .. ,i k-i.!.>
nn'a,.Ik'uni'r+ t'm ,lP-' *,f a |iiiilihln .j inr-t,.i.Ll ,.r .i h rin -i.l.'.11.1r, ,I,. ir.. .,i ..,' ,I, l.r..'* u i' h
wureimI i I 4 aI I I II' h t ,II i r L.I lI ll .1 *-i
[-it r- II'I
Tuhlr.,i *'.s;kiiaqt m dihnension. ired rubir roidents of each fl owr aind amount roifrhemical.
] nimr.n.iuns. 'h" t ariii Anil l'aler. atoem-
unds Pin. Pints. ors.
[',,und.& Pints. Pints.
BasLemn lJ . . . . x t.x x 10 *'4.l1I 1- 15 45 &
Fir.tl, fhour. .. . .... 4... ... 0 x i x l i 4i -1I1 -27 '7 81 9
,'ir nd flu,,r . . ............ .. 40 x i.. x 14 .1A x. I m i 1 21 21 63 7
Third Iloor... ..................... 40 x 60 x 1 2'%.%iM I% Ix 54 6
Fourli n iloor ........ ... ... ........... 40 x 60 x I I 1. 2- 27 2; 81 9
'rj .. ............ .. .. .... .. 172 -,, i Ink I]0 3124 V1
a .\surnin ilII- to,> of L.a ,uniJ of potash at 25 L'rnlb d puijnd. Ihi.' wouldJ bring the sum for the most
expense chemical to 527. Calt ulinenn the sulphurict at id Lt I vent< pound iI pint = 1.84 pounds)
I he cost would be 55.96 or $32 9t, as I he Iotal cost of the chemicals
Table fibr mi ills n.'ith open .qs 1.1 I1Iors
Bisem ent . . . . .
First flour .
Second loor .
IT mnnsn- l'ei ., .InlI Acid water. (sorn.
40 x tH x nTO 21 0n) '" 36it 108 12
V41 x i4) x 1% 41. 211" i,, 3.i 108 12
4n x ,') \ I I .KI) 2-4 24 72 8
4n \ i' \ 12 2'. ,ill) 12 12 313 4
III x 6'0 x I" 4! J2l1) 0 0 0 0
This table Is intended for use in hijibline htine IrTceV op,'ning,. a. belt hole,. freighl elevator shafts,
and open stairways in the floor,, ,-r. ing to) i hroi Ihe %, hole hiiili in t InIo one large roonim.
PREPARING THE MILL ORR OTILE HBUILD)IN(; FOR FUMIGATION.
After obtaining the chemicals for gen-.rating the gas the building
should be made as nearly gas-tight as possible, since upon this feature
alone depends the amount of chlemiials ti,, be used. If the building
could be made approximately air-tight, the amount could be mate-
riallv reduced with consequent saving of expense.
To compass the object dlesired, every w indow must be closed as
lightly as possible. A good way is to insert plugs of wood on each
side of the top of the lower sash antl between the "strip." If this
does not make the aperture between tile two window sashes tight
enough, other substance, mar be used. Cotton batting of good
quality is serviceable for inserting into thee openings with a case
knife, care being taken that it is packed tightly and not loosely. A
cheap grade of batt ing can be used for stopping other apertures.
Toweling or rags may be sulbstitutedl. antd after being placed under
running water can he dried and reused. Macerated newspapers
might serve the purpose, but perhaps thle best, because the most
-('cIire, remedy for general use consi.ts in pasting paper over the
aperture, uncalendered paper of the quality of cliheap wall paper or
;Il comparatively porous but not pu])llpy paper being serviceable.
New-.piaper-; are apt to be too soft for this purpose. Cracked panes
should be replaced, 4,r paper Inav be pasted over the apertures.
i Sim ilar trealtliellt .I,111Id I'll ,, ...1vni t, 0}., ,Il, i,- 1,Ld all other lm tural
outlet.'., including li, ,' iiin e\-. lir', l in'. 1llin'-. (11i-lei-. ventil.,l111 .
cracks in Ilie 'vilin-. s ii ld % il .l. Ini il iiiiihII ,I it l ii, 'li I -II. su h I i I- rat
holes in Ile l h,' 11 r. All 41I" ,li,., -Iti',uil Ie li ll\ closed.
Tt is idlw yit, l
preparation n, ii.s 1 ittr l tillt ll ,itll'l iii1\ -i.iIMii u '.c hII r t, discovered tIhatI
ha.s escapedl)l notice.
ITo pro'vitiI fi'r quriirk ntiil lli Iiriiuigz ,ltl iliIIii r111 e the process i-
Comlpletedi two or IInlIr, ipi)site \ilIi\\. limnililt le hft unlocked and
j arranged, especila in ille uii|p.r liI,.r-. -'i lnii i, ll.\ iin\ l bew pulled'
down o ti" p, as tie' n ilitm lbe. b%- viilll'l Id' , I tAilt cord or Jrope fiill
C I. F%\ N ING TIIE \1I1.1.
.1.. an ill it11 .1tl p i1 t, tiI, fillilltii 4,'n i ill or other structures
inhablitedl b1 he lhour tl l ih. it if ilpo,, 1) 1t .ii i. i ani it a;s 1 lir ,,ii '
as possille anil rei'o\e nil iiif'.-ei l lliil 1 r i-li,,,r mill product and
promptly burn it. lhlt It- uiuiiin f tlit (,lri'lilli'... pup -l anld ,L'_-
of the insect as l.s-ihlts I ,my lema ie'tnl\ l M,-.t p1,,..'r,.-i, ntiulleI's
employ a system of clet'ani,. ,nit l'iire ',iiiiii'atliwi, since llirii.r tlihe
general adoptiom If fti tiii. nli i n lt' liil'n l-< i111i pri"i incipal iillilL., cen-
ters the inly recour.e u.s ctI, l di.'e oi\Vll ti1' i ,ills (wlhchi it wa-
fouttnd neIessi. v ill om) lils ('I-, tol) I I.-) it'lii -l, twice a Zk 1 and
clean out every thin ) IY iie'lani 'l l'. iltall- It is l',',r,.l. mIp,, \,.
that too ufte'n lie I s. eel'in tii p i lI I I I)''S,(,rly l-,osed h t by iiiiI 't
The opteratime iol i'- li e ni ,iii i ,f .ill p)-i,,it.. elevator l,..-.
purifiers, and oilier |iirt. ,If ill.' iinim ltiie.ri :iit ll er equipment, a.
also the waLlls. Iiliiii_>. '-. l",r- in t,'I 111r1\ Pi r'iiol of the l,,iilhlini,
in whli'h tile inseet r.,tl, iiiil I,,l.n.n t T1 r, reason for -i,' iiiiii..
out at this timIet i.- t it i i,,l lie -ii. ; i I itIC I li.iicO1 to penelitrate all
parts of the buImilding 1. aN. lt kill tli. it',ter it il lir various -t;,i',-
Every part icle of irnfeitevil Il iir ;iinl w.v e iitllt'iiril lIi'l i might harbor
the insect or its ei-;s '.lio.ull lill .wvipt (l1nii ;iiid out until the mill
appears- to be aistihsollel %latn. 'llien ;- -,,-1-1 ;-t possible 1 li'r.fle-]I
the prelimninaries of ilIe' :ct iml fuIi limil tili -Iii Itl undertaken.
EIi'rlztor (aid ho Itf /hri,. -',F- I Ic iiiii ii., l:t ,irs infested by the
Mediterraneain floir n1olli. .lMin,.iii I,, ,, ;I',, .Id\' ed a brush similar
to to he o e illustrated (lii,. 4 1. It i.. i,;d1,1 li, t:-iki 'I. a piece 10' 1 -inrl,
board of the saint, dlmiensii,-,. :,. t ll i .I .ii ,ii-. I, litiii. the
bristles to three S.ihe,.. Sie .\ i- f.,-.iiiclt, i. li. eflvator beltwith l:il -
aThe detail.l If .airraiie,,'eui.n .,r ,i -ilr 1 iii I ir ,dl.ir- XoN .; and I,, o, thii
lBureau. %hich an' i.fr i.'rria i'ii, Ili.irlii.iln
( ir. 1121
headed bolts running thliouigh the hoard, as shown at BB, the bolts
beiig '-inl.h or 1-in.ii. The bristles on the sides ('C should be J-inch
mling, but those at I) should he longer, so that a good brushing to the
outer side of the elevator miav be secured. Such a brush (can be made
to fit any size of elevator. As it has been in use for many years
and is still advised I1v the Amierican Miller to correspondents, it is
necessarily of value, and s,,nmething similar should be used in every
Cleaning by sucfiii.- For a long time the writer Ihas been endeavor-
ing to ascertain if millers have tried thlie system (ol vacuum cleaning
advertised in our ionthlyv nmgazines, and hias just received word from
one of these companies to thle effect that it has only recently taken up
flour-mill work. The com-
--pan.y, however, is satisfied,
A ..... beVond anyv question of a
Sl tlult tihat their system
iJJ._ ,..' 44 %ill 'leanI a flour mill more
.."p v'^ ,'ly" tlhan can be done
7 B I ,,ny otherprocess. Con-
I.' i9\~,-- - ---- -. 1' sit-h ble experi in en t a l
-h/,,,W k is being done in some
_____ ,ii_ __ ,f tlh principal mills at
^j: -^.!:-.4 Minneapolis, and in one of
,le t lie,.e a plant was installed
""'"utr irli(\ soMile time ago. The diffi-
,. ,, ,ia ', ltv in this cage is that
/- tle steam pressure is not
(C' .sificient to work one of the
FIG. 4.-Elevator and b(ITr i iiuh fr ti1-,..d hI.l ... aspirator systems, and this
infested by the Mi'., I ri!]i ir I'Oir ira.,r h
matter is now being inves-
tigated with a view t,, changing le phint to i mother mill where suit-
able conditions can he ,btaineil.
METHOD OF '.,T[RIN(IN(; A I ,ILlDIN<; FOR FI'MIGATION.
While the "stingining" metlhod ol fuimigating rnills ::und other large
liu ildings is scarcel v necessary, t I ere re s, nme p)ersuns who may wish
information in regard t, it. Tire strings, a;re arranged so as to hang
directly over each gcnenraitor, andt are carried through screw eyes in
the ceiling or woiii1work to doors or st iirw uvs leading out of the
room to be treated. The cruw evyes s-hould be lirmly secured, and
the best quality of cord of tie proper size should be employed.
The ba'grs cotnaiiii_. thle rYvanitl if potn-hi anre suspended directly
over the ve'.-,cl, pteferably after tlhe acid is added to the water in the
fjar, ('n11 Iolr l t L tiik l bi iiI tl i, i i- 11, I. l. N I IIi IIi' ,l Iii| iI' I L I
tllP ^Cl P'll'l Oi i" prm llinlllrl'\, A ,l,,~ll \ li lI',ml> -,| ,, I,., l ,, I" ,.i ,,r]'
oif cnrll' (,ill'<[ I'll fi l ,t I ll-f l. l ll if lIlir' ..l i mi i~ I i,', lilllll\ ;.riin iin l Il l ,
nleck of tihle sick itl cilll.t". i'- li i l il I il,,. I, l il..,ril r TI I IV.
Ctil'lls .I llllV b eP *,I ill 'il ll l'Cl l t ll iil ll r \.ilili ,ll ,i l.l i l \ l'i',' l iA t,
i th il'i llI l ci H u' llltlil i i i''l llli ll a r'i -- I \ II \ ll''llli 1i\ lflit,
II atc Iiip Lil1 ilig iIiitr'11 l itiiiK,1 I I hI,
A Mi ore1" tIlcl iilnll li", riill iii' i 11f Hllit "-1 1 111,l11. iiir, 1>\ liil IL
Mlm an "' bZ10 of 'v iin l fiiH i\' I' |I,\\ 'i',l iit-ii ll r .L' tni-, \,"|I
roeqlire too lilllIci llI|iie', f i II 'iill l ir l I r, .. i'l1 ii' ilm,. If ILi
cho ses his lii iitli nl, ill N. 11i l1i )\ I I IN, i,'.-.. i'll v, :iitil I,' \v
^ "1 n i
I I I I r i
1/ _LL2// .... .w \1
Fir.. -rS n.Ir lh in i 1 ,[1 IlIIl'". i Ilrir' r l i il ' I -i. .1 r i r .' jri l
eyes are [rucli.il lit' z1I% il t I it' ill t i|ilir il 'ii "Fr Ili i ii '.11 riI'_'1
The nim etIhod i. n iul h i.sl i liiliiiI U, 'ik .ii, I- i ilf.ild, fr
small buildings. This ])i'ctt's uf "o.f ii'.L'iL!r tli, liiilli,. ,iilol
Iscarcel-y be fotuUu l prulliti:l le fur n1il ll o ri iI il l>iil ii '_'I'ulli ii.si'
work fuiniigation is freqilienlly ilii. t1,\fr U .k o11 l\v' l ;ii, I "fifteii
several times i week, niii li tiH Uiiipm'enil utf u,.-Iv% %C iilll,.% ,. rl'.,
can remain in pla'e almost iinieflinlilY\.
Signs should he phi, l -n m thin l iliih >l' I ,1 f lire buln iliii i- ,ii,
fumnigatedl, warrfing pissi.'s-1y l'f the ':n l Pr.. e. 1iin'r
lvdlrocvanic-acitI d is! '" Phi.,i" Tin' lI)tiiltling ini-It. ,if cI-,ir-,,
be vacated anti neighbors 0 iii'nctl I4'f theli nature of tih' ,,pr;iti,'ll.
Frequently these precautions are not observed, and although no
asiualt ies are on record it is the part of wisdom always to be on the
PROCESS OF FUMIGATION.
In thle process of generating the gas the water is usually measured
in a glass beaker indicating ounces, andti poured into an earthenware
crock or generator. To this is added the acid, measured in the same
Leaker, which is slowly and gently poured into the water to avoid
-plashing or boiling. The acid should never be placed in the genera-
tors first, as advised( by some writers, since experience shows that
this is dangerous, spattering being almost certain to follow. When
the acid is poured into the water in the jar an ebullition of vapor
sometimes a rises.
When the cyanid of potash is finally dropped into the combined
acid and water mixture an ebullition or bubbling also takes place
similar to that which is produced by a red-hot iron dipped into cold
water. Next is given off the hydrocyanic-acid gas, the most poi-
sonous gas in common use. It is colorless and has an odor which is
likened to that of peach kernels.a If the fumes are inhaled they are
almost certain to prove fatal; hence the necessity of extreme care
and the advisability of two intelligent operators in this work. It is
even advisable, especially when the first fumigation is undertaken,
that one who has had experience with this method of fumigation be
present to give directions. The odor is decidedly metallic, like that
produced by striking two pieces of metal together, or of metal against
InII preparing cyanid o(if potash for use it should be broken into
lumps about the size of an egg or a little smaller, by pounding it on
ai stone in the open. The cyanid should never be broken in the
hands nor should it be handled without rubber or leather gloves.
The smaller fragments, if not too many, are serviceable when equally
apportioned as regards large and small particles, and weighed out
in 3-pound lots and placed in paper bags or sacks.
Thie bags should be of moderately thin paper, because if as thin as
tissue thlie action of the acid might be so rapid as to constitute an eld-
ment of danger. If too thick, action would be delayed or checked,
which would militate against the desired results. Before use, the bags .
sliould he placed in a can and kept free from moisture, which the
,'vanid salt is apt to absorb from the air, affording opportunity
for leakage through the bag. In some cases, to avoid this leakage,
tio,, tlhin bags, one within the other, might be necessary. Washburn
expeiimniented in the use of two sacks with the result that at least 7
21l -e'omids elapsed before the gas was evolved.
aThe wrii er fails to detect tilie resemblance. :
A. ,oni as il lpreliminaries have beeIn ;I I _.,'I afi (I the licid
hnI, I)ben added I' t he tit< water in the g neratiors, a l';,_. i **,it .iiiii.' the
cYvanid t.ould he Ilf at the side (if each .i.l', iir.
.\fMtr -',iiig that the *il *i'. rIc placed in rows so as to 1illrd
o'Ip)t'1 il for rapid action andt thie acilhas libeen added t the
wiltir in each of the jiii. h,.-ir, opl)rations in the(, uir floor of t he
building and place lthe cyanidl ._',ill\ ini each jar. -i,- liin one
jir it, niiother as quickly as ssible and ans quickly lea\ %ir-' the rioom,
gi ii -ilwnward to the next floor, where the process is repeatled until
then' [l.1 floor or bIasemient is reached, where exit is made. The outer
doors -.iould be locked and a watchman stationed outside until tlie
prve-s is completed.
Thi- process may he varied if sWtino.'> i)r stotit cords re us('ied for
lowering the Ira.. of cyanid into) the jars fronm the outside, 's pre-
viou'l % described.
A -till day should be selected for fiiL..il n. In case of a hi.h
wind tnhe f"iie., of the orni, will escape stiii,.lyv, which will not alone
int(erfer,' with the success of the flni&. .lin, hut Innav cause alanii
to neihibhl, rI. shill the 1u,,illini.. not be an isolated one.
Better results are claimed for a warm temperature, say 7(1 F.
or love, than in a temperature as low as 0) F. o)r l)elow. I'ndr
5(W i1-0 insects become to rpid and the effective action of thlie chemical
will le diliini-hL'd, '-ipc iilly in very low temperatures.
The best time that ,uld be cli'-vii, anid which is generaIly used
where circumnistanves p',rinit. is diiiis,. daylight on a Saturiday after-
no in or v erV early Sunday Ti,,iiviiL,'. This iri, a l1.i-i i exp()osure
than ctin usually be obtained unless a day jllri.,ling a holiday, Iwhen
all mill hands are on va;ii-ntii. may be chosen. This permits of a
full exposure, as in many cases it removes the necessity of vioil.,i ii,.
tthe buildiilo until early the iI'llo\inr i[, he V iii 117 .
A single fiiiii-,ition will in most cases destroy aill but a few indi-
villiLI indeu-.. especially if conditions are favorable. As a rule, ihow-
ever, it is nlyv a matter of a few days or weeks before the mot ihs may
hle seen lnrgiiinir.,.. to lyI about the lniildiiL or i,-ti).. onI the walls
and inahinerw. To guard ni.'iiin-I reinfestation, therefore, a second
treatment nmust be given, at the end of the third to the fourth week,
according to the nuTnt)r of moths which may have issued in the mean-
time. If Afier the expiration of another interval tlhe insects are still
present a third finiiiig,_ti'ii may be necessary. A third treatIment is
not ustuanlly reIliir,,. however.
Most miller who practice this method of f' i-i:iilai: eniplov it
,n(e a yeiir, some at the intervals above stated(l, others at intervals
of ;ix niontihs. One M.liiigei miller claims that in his case after o)ne
thorough,, fiiii.., iiii it is unnecessary to repeat the process until
two years have elapsed.
The cans or other receptacles containing the cyanide of potash
should be plainly labeled "Poison!" and each operator should
become tliwr iiuglhly familiar with the dangers which may attend a
failure to carry out directions exp)licitly.
POSSIBLE DANGERS IN USE.
As soon as the bag containing the cyanid is dropped into the
generator the operator passes quickly to the next generator, and so
on. It is not safe to linger under any circumstances or to return in
case of any omission. Any deviation from the set rules may mean
the loss of life.
The residue in the fumigating generator after the operation is
completed consists of sulphate of potash, sulphuric acid, and water.
Sometimes if the chemicals are not of the proper ,t rength or are not
properly combined a certain amount of cyanid of potash remains and
hydrocyanic-acid gas is given off. This residue is an element of
diiinger and should not be left in the generators after use, but promptly
poured or thrown into a sewer trap or buried. The generator should
then be thoroughly cleaned in running water.
A question often asked by persons contemn)lating the employment
of the hydrocyanic-acid gas method of treating buildings is as to
whether it is dangerous to the contents. It is apt to tarnish, though
not permanently, polished brass and nickel when exposed to its act ion.
Where such fitt ing- can be conveniently removed it will save trouble,
otherwise they may be treated after fumigation as if tarnished
through any other cause. Liquid or moist food materials, such as
milk or meats, are apt to absorb the gas and should therefore be
It is not positively known that fires are an element of danger, but
persons experienced with this process are united in the opinion that
to avoid the possibility of risks all fires, gas jets, and the like should
be turned off. There is a possibility of explu.iun when a gas is gen-
erated in a tigliht inclos-ur,, hence the precaution.
After what has been said of the deadly nature of hydrocyanic-acid
gas it should be added that there is really no danger if the directions
given in this publication are carefully carried out to the letter and
the vapor is not inhaled. Even to taste the salt might have fatal
results, and it is dangerous to inhale much gas, as this might cause
asphyxiation and death.a Undoubtedly thousands of successful fumi-
a Scores of entomologists and others, including mniany enimplyee- of the Department
of .\-ri iultiri, have successfully used this gas for fumigating rooms and buildings.
It is in general use as a greenhouse fumigant and for nursery stock and the names of a
hundred persons could be mentioned who have had practical experience with it.
gill, n. have been made of inclosures and as ,et n, fat alities have
re'ulIeld. Yet it is Iworthi reiIIeiln il i' llhat operators after i:l.iliL
iniiiln,,(-i of fIrii-,rinnii, are apt to lecomile caril.--. a telencli wl icih
.AhouIli be a\ ,iilt.d
(hio f 1'irii of accident s6uhIl be mlent ioned, however. If a iii, ittiiL
of iew.,paipeI,- or similar material is not played untilid each fIi i,='. I ilL,.
jar, or if the water is addhd to the acid, insItead of lithe reverse as
uMavi-e] in this illhli 'ii. the acid is apt to run over hlie .o.rii ..lor
atindl injlre the thli or splash upon thlie 4clliiI,." or even "v 1e' hands of
If care is observed in lil',li., thie receptacle-s I r- liiiiin the
cheinicil-. if the operators before ti-ii,' tis l.thi d l eImcomle thor-
oughlyv conversant with it. and if -i'r, Iare placed on thle doors if the
huildinz,. the chances of accident will be redticed to, a minimum if
not entirely eliminated. After filtii'.t..ion bluiillir-.- should nevIer be
unitcre W il at least a half hour '.i, hour or two is safer) has elapsed
after the doors and windows have been ,'irii' I for ventilation, and
tundht.r no consideration should an olperator return to thle place just
vacated w hen the operation is tuinder way.
SUMMARY 0F O"PE1SATION S AND IP'REi'A't TIONS.
1. I'se pure chemicals, ".ii ..trs ,as prescribel, ,nd pa per n,.\-.Ao
(f PiI,,l.r quality.
2.. M;ilk, every portion of iiiili:1 as nearly _..ri-ti_'it as po-ssible.
3. Maike first fumigation 10 ounces to 1,111111 cIulbic feet of space,
unlIess building is unusually loose, in which case mo)re must be used.
-4. Repeat fiiuniii'. lii' at end of three or four weeks if mioths I,.'_in
Ii'ii,.. or other evidence -If infestation is shown.
5. M oi.-aa re every portion of 1biilik-i-' carefully for calculation of
tlie pril r options of chemicals.
0. Operators should lbe int,.ll i't.ni and reliableI. Any bookkeeper
Can readily calculate the cubic contents and piroiportins .f ('he]icals
to use. Careless men should not bie employed.
7. Precautions should ble iaide for prompt ventilation fromn with-
,,ut, t't,.t 5umi._' tion.
D Purim, July, P'oi. a Mi, Iji.:_ iiiii i r re ported that wlki, u .,- 35 crnxk- a. -.., -
aiil-r. 14 of them boiled over, the -oents .iU_.1 the tlwnr bad-l. The exilanauin
ian h i. ease was twofold : First, the cyanid i bro. ,ken into 1 t t nmall inis ., 1.. *. r .1
a1 about ih,' size / of,' i ... berrites, and the I 1 r- on which the i. iii.: ,iVr w1 wnrm mi t
were the two upper .-in while no a( cident h1apieWld in thOe haw menl This hap-
Ip r.1d liluriir.: very warm r.ih.,u r the t ..l I r. 1.. ii-_ h1 t l.. the ba-ement wa
naturally col. The miller reiirted the '..liii o ver ai t'oll+>v-: Sejven ,IUt of I) on
the third il.-'.r 5 out of 10 on the -", ii.l. 2 out of 9 on the tiir, none in the ba ment.
8. Dinmer signs should be placed in position and a watchman sta-
tione(d outside until (lie operation is concluded.
9. Before fiinii,,aliiin, clean out the mills Ih,'ougrily and provide
for the penetration of the gas to every portion 1)by moving bags,
10. Do not fumigate in a high wind or in a low temperature.
Between 65 and 85 F. should produce the best results.
11. Begin operations in the upper floors and pass (uiiicklyv down-
ward, pll intr the cyanid gently in each jar.
12. Fumigate preferably on a Saturday afternoon, lock the doors
after operations are completed, and expose from twenty-four to
thirty-six hours if possible.
13. Never reverse the order of procedure. Always pour in the
water first, next the acid, and lastly put in the cyanide in bags.
14. The operator should never return to the building after the
first fumes begin to issue.
15. Everyone connected with the fumigation should constantly
bear in mind the deadly nature of the cyanid and the gas and 1be con-
versant with the process and( the necessity of caution before the gas
ORDER OF PROCEDURE IN FUMIGATION.
Briefly, the fumigation of a mill or granary includes the following
1. Meituriing the mill and computing the amount of c'lemicals
and number of generators required.
2. Seiiring the chemicals and the generating jars.
3. Preparation of the mill, including cle..:Iling, sealing up as nearly
air-tight as possible, and arrangement for ventilation from without
after the conclusion of the fumigatin, and preparing signs.
4. Distribution of jars and measuring into each the proper amount
5. Breaking up the cyanid and weighing and placing it in 3-pound
lots in sacks, temporarily tiring it in tightly covered tin cans,
preferably a can for eaci floor.
6. .MA-.ulliiig out the acid and adding to water if jars.
7. Placing a bag of cyanid in each jar, beginning with the top
8. Tightly closing and locking the building and seeing that all
W1ruing .-1i,'1 are in place, amnd, if necessary, stationing a watchman
without to guard the building from entrance.
9. Opening the building from without for ventilation.
10. The collection and disposal, in the sewer or in a pit, of the
residue, the cleaning of generators, and sweeping out dead insects
and other (debris before resuming work.
IFFlA-:< T OF I tI IIR)( 'ANI('-tUIl> iAS I' ( L\TlOX ON SEA1 M\ TERtIAI..
As t ttl he ll,,''t f h ov 1'11ati(-uid .I tl the [t'c i ir l.,idl 4o of
seeI.a series of tests wus cohlldctell d, lI )I (I. (t ) nl' enl, now
Of this I)epart iii'l. wihen connected w iit ti Ne :lar1 lad st( hirti-
cihitiii depI art p i i wI, ith t1he r\soiltm ir cfii.h clui-oi that dI I .ii -r
ii111 other seeds can be I tr ted w% ith l\k 11 1 i1ui i1id 'i--f lr insect
Ieists at the usuat l sl iini.lh a dtI t :ilini', or e11 en fIor s,\ velil d isx '.', iI I I4 tt
ill lil V \% I' \ i' l iiii.. t ,le gr.i i Ii iii X liirh iNo Ii hI hOir I I illilt in
the ordinary process t his lietiol of f-ii_..ion rlll Ie eiplot,(d II
\ without injiirilii..z seeds eiiiher for plniiit li or ns food. tuiiip L-i.,i,-
iliil oilier 'vel-. hoI ever. re nio I e sii c e i li to thle i lli of
h lid,,.\ iiil'-ili,'l..'1i- 1. a Ild o in (, |) le< tiolf i ni iI lj I e ol s I v ed ill Slich
('LSes to) avoid mloistlilre.
\VhiI' the It.lij, ti oi f t he pire'veit ciro hil "r i,; to fnrfii'lih ilif'Irimationi
for the fiirii' .'it i'm of n 1ills an1d 1 t1e, r it I lli, II .I 11. 1 h11ZrI-c a ni -I cid
gs is a remedy f 'i"r the flour ilnot li. it \oid lie n I) wi.e to omit 1ti t-
nil' that there arl'e several other ,."odI reinelies, '( i, 1. however, are
not it ii v-; l)ossildle of applic-ation.
B ;.N: 0/lii1 J ca,,.bo. ( )-ne1 of t hese is c isulpIhid of val'a Ii. especially
fori small incIosures. It is claimed bv solie inillers to be of value for
a first fu in itt iti, f, i',\\ ii. it w ih hIydrocyanic-acid _'.i-.' When
forced into the -'.lillt-.. Illach iiliery, anti other pi lions of the uii11, it
is a factl r in killing the moth and other insects.
f '1, f11n '1. 1 -T]e maintenance of scrilpiioins cleanliness 1n' Ili-
out the miill undoubtedly does much toward pi, \ii, t iii- tlie int rodiuc-
tion of the flour mnoth as e\'ll1 as in rest iiiii:iiL its iIncrease after it
has once obtained a foothold in the mill. l)irectioIns for ,iiL
have been givenl on pii,'e 1I Prominent millers in soimei of our l.,i ,'v
cities. e. g.. in Loiiiville, Iy., and in Kansas ('it v, Mo., as else here,
have attributed immnunitv from the flour mothl to the fact Ithat they
main aiit the most ii'il -y'i 'l1ii of cleanliness in their mills.
Siuphlaur \\ as used somewhat extensively ais a remedy for the flour
mothi several %,ar-; before the general employment of hvydroc.vanic-
acid gas. and it is still valuable and in constant use by millers in some
States. Lack of space prevents further discussion
Where an infested mill can be lft open to a t,.rllpir' il 'ire of zero or
lower, three to ten iii,1i1t- of such exposure continuously or at inter-
t Detail in r.-:rli to the ,iiw'li, iiii of biaul phid of c'arh, m for f.ii.'.in: build-
inL are i iv,''ii in -.irmii'r-' I 'iil.liin No. 1 I pp. I'i -'i )i. ther vauable information
re'arlin i hif insecticide is also furnished. ('opics 1 ll be obtained _'riti- on appli-
cation to Mfnill.rm of I ,'tri-- or to the S-. r,,I.ir,' of A-ri. iiir,
vals will be found effective in destroying the flour moth in its dif-
ferent stages, unless the mill or other building happens to be a heated
one. The moths are not apt to breed to any extent during the
winter, hence there are few eggs to deal with at this time. In north-
ern mills which have been much affected by this insect, especially in
Minnesota and Canada, where the temperature is frequently 20 to
:3( F. below zero, this method of destroying the pest has been pur-
sued x4th most excellent results. Speaking generally, it should be
practiced wherever the temperature warrants the process. There are,
of course, southern mills, e. g., in Kansas and Texas, where this
method would not meet with much success.
Secretary of Agriculture.
WASHINGTON, D. C., January 22,1910.
.- .- m ..ia
UNIVERSITY OF FLORIDA
3 1262 09216 5421