767

AI^aaiTIGAL CATTL:^ DIP3

U.S.D.A. iSul, 603

By :^. M. Ghapin

August 1914

..,i.,i,ili;;: -5^75 7 .^^.o.-^-^""^- Mai« uteM,

LIBRARY
G

U.S.DEPARTMENT OF AGRICULTURE

603

Contribution from the Bureau of Animal Industry, A. D. Melviri, Chief.
August 14. 1914.

ARSENICAL CATTLE DIPS:

METHODS OF PREPARATION AND DIRECTIONS FOR USE.
By Robert M. Chapin,
,, Senior Biochcntist, Biochemic Division.

INTRODUCTORY.

This bulletin is intended to be a handbook for the user of arsenical
cattle dips. It aims to include in brief but ample form general in-
formation, formulas, tables, and practical hints bearing on the prepa-
ration and management of
[arsenical dipping solutions,
kit to this field it is
strictly limited. Those who
Hesire a popular account of
[the life history of the
[Texas- fever tick and of its
Irelation to cattle are re-
ferred to a previous bulle-
|in (Farmers' Bulletin 498)
|issued by the department,
'he same, as well as an-
)ther previous publication
[(Bureau of Animal -Industry Circular 207), contains plans and speci-
Ications for the construction of dipping vats, together with directions
for the management of cattle in connection with dipping.

PROPERTIES OF SUBSTANCES USED IN MAKING DIPS.
Making a dip is simply a manufacturing j^roposition. Xo manu-
facturer can expect to get the best results unless he is somewhat
icquainted with important facts regarding his raw materials.

White arse?iic, also known as arsenic trioxid, arsenious or arsen-
)us oxid or anhydrid, should always be purchased in the form of
fine powder, and under a g-uaranty of 99 per cent purity. Water,
iven when boiling, will dissolve only a little of it, and that slowly,
)ut by the use of certain other chemicals white arsenic may be readily
md abundantly brought into solution.

White arsenic is a violent poison, and users of it must never allow
familiarity to beget carelessness. It may be absorbed into the
system and cause injury or death, either through the mouth, the

47702°— 14

487^60

(S^^

\^^

Fig. 1. — Map of the United States, the shaded area
showing the territory to which this bulletin
applies.

2 farmers' bulletin 608.

lujigs, or the/.ski.n; tl'ontfwj't 'neither the dry powder nor the solution
should be allV)\vVd t?)*rei^i':ii*n*oii.thc skin. The breathing in of dust
arising froijrrrltiP,*;Tp\-.;6o\Ttl'i»r. (firing handling must be avoided,
while, if'caftle Vre iJeiiig s'prayed, neither the operator nor the cattle
should inhale any of the spray. Moreover, from a boiling solution
arsenic may be thrown out as a fine spray and also, under certain
conditions, as the very poisonous gas " arsin.'' Hence, concentrated
dips should be prepared only in thoroughly ventilated places, while
all work should be done on the windward side of the kettle and as
far from it as practicable.

If arsenic in any form has been swallowed, medical attention is
to be obtained as soon as possible; but since promptness of action is
of very great importance and medical attention is not always readily
available, it is best for all who use arsenical dips to be familiar ^ith
first-aid treatment. The United States Dispensatory (nineteenth
edition) has the following to say in this matter:

If the antidote * * * be not directly at band, free voinitinp sbould be
induced by tbe finger, tbe featber part of a quill, and the aduiinistratiou of an
emetic; * ♦ * Demulcent drinks sbould be freely given, .such as milk, wbite
of eggs and water, or flour and water, which serve to encourage the vomiting
and to envelop the poison.

The antidote having been faithfully applied, tbe subsequent treatment con-
sists in the administration of mucilaginous drinks and the treatment of
symptoms as they arise.

* ******

The antidote above referred to is * * * ferric hydrodUl with mnuncsium
oxid in the moist or pulpy state. As soon as it is ready it must be given in
doses of a tablesi>oonful to an adult, of a dessertspoonful to a child, every
five or ten minutes until the urgent symptoms are relieved. * * * Its
efficacy is, of course, greater the sooner it is administered after the ingestion
of the poison; but even after delay its use will prove advantageous so long
as any portion of the p(nson still remains in the stomach. ♦ ♦ ♦ It should
be an invariable rule to prepare the antidote at the time It is waiittnl from
materials always kejit at hand. • ♦ ♦ 'phe best antidote known is the
combination of ferric hydroxid with magne.sium oxid now recognized by the
U. S. Pharmacopoiia.

The materials for the antidote referred to can be supplied by any
prescribing jjharmacist, contained in two l)ottles. In this separated
form the antidote keeps well, and when an emergency calls for its
u.so all that is necessiuy is to mix thoroughly (he contents of the
two bottles and to administer as directed. But in any case medica^
attention must be obtained as soon as possible.

Sodium carhonate. — Also known as sal soda or washing soda,
when fresh consists of colorless trans|>»irent crystals. On keeping,
unless lightly closed from the air, it tends to lose its crystalline
apix-aranc*". and to fall to a white powder. This change is due
morcly to the fact that the crystals carry a large amount of com-
bined water (water of crystallization), and on exposure to the air

ARSENICAL CATTLE DIPS. 'S

much of this water may evaporate with consequent destruction of
the crystalline form. The soda itself is in no way affected by this
loss of water, except that it really becomes stronger, weight for
weight.

Another form of sodium carbonate, called " monohydrated sodium
carbonate," also occurs in commerce in the form of a white crystalline
granular powder. It contains only a small amount of water of
crystallization and is practically unaffected bj^ exposure to air. This
form of soda from a manufacturing point of view is far preferable
to sal soda, as it is of constant and permanent composition, and
being much stronger, weight for weight, it is less expensive to handle.
When using monohydrated soda it is necessary to remember that
only 4rJ pounds are needed to do the same work as 10 pounds of
sal soda.

Pine tar. — Pine tar when fresh is semiliquid, but with age becomes
granular and nearly solid, in which condition it is of less value.
Mixed with it is always more or less water of decidedly acid prop-
erties (pyroligneous acid), which on standing tends to float on the
surface and should be dipped or poured off before the tar is used.

Tar is heavier than water and when stirred with it usually forms
a very poor mixture from which most of the tar rapidly settles out,
but when the water is of just the right temperature and somewhat
alkaline a fairly stable suspension may generally be obtained. Wlien
previously treated with an amount of caustic alkali sufficient to com-
bine with a considerable proportion of the tar acids, or when blended
with soap, the tar easily mixes with water and then forms a good and
permanent emulsion.

Caustic soda. — Also known as sodium hydroxid, or sodium hydrate,
on account of its wide range of application by chemists, pharmacists,
and manufacturing industries occurs commercially in a number of
different forms, as powder, flakes, solid masses, or broken fragments ;
m color ranging from pure white to grayish or brownish tints. For
the use of chemists and pharmacists it is put up in glass bottles; for
industrial purposes it is supplied in various sized cans or drums of
thin sheet iron. The latter is the variety that should be purchased
for making dip. Its large output and wide use render it easily
obtainable almost everywhere — far more so than white arsenic. The
10-pound can is the best size to buy for home use in preparing dips ;
larger consumers can probably handle the material in larger drums
conveniently and of course more economically. The purchaser must
make sure that the contents of the drum he contemplates buying are
in fragmentary form, or granulated, for much caustic soda is run
into drums in a melted condition and on cooling forms a single solid
cake, which, though satisfactory for factory use, is not adapted for
the present purpose. It should always be purchased under a guaranty
of not less than 85 per cent actual caustic soda.

4 farmers' BFLLETTX 603.

Caustic soda is an intensely active and pr>\vt'rful substance. When
exposed to the air it strongly attracts moisture, increasing in weight
and becoming pasty, while at the same time it becomes contaminated
with sodium carbonate through ab.sorption of carbon dioxid. Hence
it must always be purcliased in original containers, never in bulk;
the container mu.st not be opened until just before the material is
to be used; the substance must not be allowed to stand exposed to
the air, and if any is left over which is to be kept for subsequent
use it must be immediately transferred to a tin pail provided with a
tightly fitting cover, such as a lard pail, or, best of all. a paint pail
with a friction top.

Owing to the intense chemical activity of caustic soda it is ex-
tremely corrosive in its effect upon .skin or clothes, and upon the lungs
if dust from it is inhaled. Therefore it is necessaiy to handle it
gently to avoid the raising of dust and to wash off at once with wat^r
any which may touch the skin or clothing.

Caustic potash. — Also known as potassium hydroxid or hydrate, is
very similar in its properties to caustic soda. It is not, however, so
widely used industrially, and is decidedly more expensive without
being any better for the present purpose. Therefore it should be
purchased only when caustic soda happens not to be available. In
its use one must remember that, weight for weight, it is less efficient
than caustic soda, so that for every pound of the latter there must be
employed 1.4 pounds of caustic potash. Like caustic soila. it must be
guaranteed at least 85 per cent pure.

Lye. — This is a term employed to designate a grade of caustic soda
put up primarily for domestic use, such as making soap from waste
grease and for general cleansing. Since ordinarj' buyers of this
grade of goods are not apt to be able to judge closely of its quality,
it is sometimes of very inferior grade, though not necessarily so.
If any guaranty regarding its purity can be obtained, it may be used
for dip making, in case of necessity, in the same proportions as
caustic soda.

THE GENERAL COMPOSITION OF DIPS.

All arsenical cattle dips contain arsenious oxid as the active tick-
killing agent. But since straight ai"senious oxid, that is, M'hite ar-
senic, is so slightly and slowly soluble in water, it is necessary to use
some other chemical agent, such as sodium carbonate or hydroxid, to
bring the arsenious oxid into solution. In this way the white arsenic
is changed to sodium arsenite if either sodium hydroxid or sodium
carbonate is employed, oi- to potassium ai'senite if the corresponding
potassium compounds are used. Starting with a given weight of
white arsenic, whether it is converted to sodium arsenite or to potas-
sium arsenite appears to make no difference in the action of the
finished dip.

ARSENICAL CATTLE DIPS. 5

After the white arsenic has been brought into sohition, a variety
of substances, such as tar, soap, oils, etc., may be added with one or
more of the following objects in view: (1) To increase the effective-
ness of the bath against ticks, either through greater penetrating
power or better adhesion, or through repellent action ; (2) to render
milder the effect of the bath upon cattle; (3) to denature the bath so
that cattle will not drink it. Proprietary concentrated dips differ
from each other and from home-made dips essentially only in the
nature and amount of such added substances.

MAKING THE BOILED DIP.

The boiled dip has been recommended for use in two strengths, the
baths corresponding to which will be termed here " low-strength
bath " and " high-strength bath.''' The low-strength bath is com-
monly used for ordinary tick-eradication work on the range, the cattle
being dipped regidarly every two weeks for possibly several months.
The high-strength bath is used to treat cattle which are undergoing
transportation to a tick-free region, the treatment being usually
limited to only two dippings, 5 to 10 days apart.

To make 500 ^ gallons low-strength bath provide :

Sal soda* 24 pounds.

White arsenic, 99 per cent pure, in fine powder 8 pounds.

Pine tar 1 gallon.

Put 25 gallons of water in a kettle or tank of 40 to 50 gallons
capacity, heat to boiling, and add the sal soda. When this has dis-
solved add the white arsenic, then boil and stir for 15 minutes or
longer, until the white arsenic has entirely disappeared. If intended
for immediate use cool to 140° F. (by the addition of cold water if
desired), then pour in the pine tar in a thin stream while constantly
and vigorously stirring the solution. Immediately empty the liquid
into the dipping vat, which has already been three-fourths filled
with water, and stir thoroughly.

For a stock solution to be kept on hand and used when needed, add
no tar, but, after the solution of arsenic and soda has become entirely
cold, make it up to 25 gallons (see method on page 7), stir well,
let settle, and draw off into containers which can be well closed.
This constitutes " low-strength boiled arsenic stock," and its use in a
diluted dipping bath calls for a "tar stock," the preparation of
which is described on page 7.

High-strength bath or high-strength boiled arsenic stock is pre-
pared in exactly the same way, except that for 500 gallons of diluted
bath there is used 10 pounds of white arsenic and 25 pounds of sal
soda (or 11 pounds monohydrated sodium carbonate).

^ The number of pounds of white arsenic needed to make any number of gallons of bath
of any strength may be obtained from Table 1, on page 11.
*0r monohydrated sodium carbonate, lOJ pounds.

6 farmers' bulletin 603.

A by-prcKluct of the action of sodium c:«rl»oiuile vn white arsenic is the gas
carbon dioxid. The esonjie of this gas is attende<l by considerable foaming
of the solution, so the kettle must be generously large, and the operation of
boiling must have constant watching to prevent the liquid from frothing over
the edge of the kettle.

The kettle or tank, utensils, and materials must be perfectly free from all
greasy or oily substances, since a small quantity of such matter is sufficient to
form a coating over the arsenic and thus to prevent or delay its solution.

The boiled dip may be made perfectly well with very hard water, but. in
that case, some residue of a line white or gray powder will be left undissolved
after boiling. This residue carries no arsenic, but arises from the action of the
sodium carbonate upon compounds, chiefly of lime, in the water. Examination
of the liquid after boiling for a few minutes with the .smla before the arsenic
has been addp<l will show how much residue may be e.xpected from this source.

MAKING THE S-B DIP.'

The S-B arsenical dip was developed by the present writer about
two years ago to meet certain drawbacks to tlie boiled dip, namely,
(1) the necessity for boiling large amounts of liquid, and (2) the
impossibility of preparing highly concentrated stock solutions.
Bureau employees in the field have given the preparation a thorough
test in practical dipping. The difference between the S-B dip and
the boiled dip is merely in the formulas and methods of preparation,
the composition of the diluted baths used for dipping being prac-
tically the same in both cases.

The S-B dip is prepared in two parts which must not be mixed
except in the diluted dipping bath, (1) arsenic stock, (2) tar stock.

S-B arsenic stock requires the following materials ready to hand
before starting:

Pounds.

Caustic soda,^ at least 85 per cent pure, dry, granulated 4

White arsenic, 99 per cent pure, in fine powder 10

Sal soda,* crystals 1 10

In a 5-gallon kettle or metal * pail place the 4 pounds of caustic
soda, add 1 gallon of cold water, and stir with a stick until the caustic
soda is practically all dissolved. Without delay begin adding the
white arsenic, in portions of a pound or two at a time, as fast as it
can be dissolved without causing the solution to boil, stirring all the
time. If the liquid begins to boil, stop stirring and let it cool slightly
before adding more arsenic. The secret of success is to work in the
arsenic fast enough to keep the solution verv-^ hot — nearly but not

^Abbreviated from " self-boiled," the name betug suKuestcd by tlie fact that the hcnt
necessary to prcpnie the dip Is wholly derived from chemical action bctwpcMi the raw
materials. '

" Or r»4 poiiuds dry caustic potash of cipial purity.

"Or 4 J poundH monohydratcd Bodluin carlionate.

< Tlic chcnilcnls cmplo.Vfd linvc no i-ITccI upon Iron. Thoy will, however, actively (or
rode zinc, tin, or Holdi-r ; licncc a soltlcrcil pall raiiHt bt- watched for h-aks and Is f:n-
inferior to a HeiinilesH pall, siiuuricd from a sluulr' shrel of Iron. A tinned pall Is pre-
ferred to a j;alvaiil/('(l one, but a plain Iron HeanilcHs pull or an Iron kettle should be
obtained If poHMlbli-.

AESENICAL CATTLE DIPS. 7

quite at the boiling point. The result should be a clear solution,
except for dirt. If the liquid persistently remains muddy or milky,
it may be because the operation has been conducted so fast that much
water has been boiled out and sodium arsenite is beginning to ciys-
tallize, so add another gallon of water and stir. If the solution does
not then clear up, the caustic soda must have been very low grade,
and the undissolved substance must be arsenic. In that case, put the
kettle over the fire, heat nearly, but not quite, to boiling, and stir.
As soon as the solution of arsenic is complete, dilute to about 4 gal-
lons, add the sodium carbonate, and stir until dissohed.

Cautions : It is necessary to avoid splashing. Hence never work hurriedly ;
stir deliberately and regularly; do not dump in the arsenic and sal soda, but
carefully slide them in from a grocer's scoop held close to the side of the pail
and to the surface of the liquid. Perform the whole operation in a well-ven-
tilated place and avoid inhaling steam.

After the solution has become cold add water to make it to exactly
5 gallons,^ mix well, let settle, and draw off into containers which
can be tightly corked or otherwise closed. Jugs or demijohns are
best, but tin cans will serve if occasionally inspected for leaks which
may occur after a time through the action of the solution upon the
solder of the can.

Tar stock appropriate for use with either S-B arsenic stock or
boiled arsenic stock is prepared thus:

In a capacious metal pail dissolve three- fourths of a pound of dry
caustic soda or concentrated lye (or 1 pound of dry caustic potash)
in 1 quart of water, add 1 gallon of pine tar, and stir thoroughly
with a wooden ]3addle until the mixture^ which at first looks streaked
and muddy, brightens to a uniform thick fluid somewhat resembling
molasses. Test it by letting about a teaspoonful drip from the pad-
dle, into a glass of water (a glass fruit jar or a wide-mouth bottle will
serve) and stimng thoroughly with a sliver of wood. It should mix
perfectly with the water. Globules of tar which can be seen by
looking at the glass from underneath and which can not be blended
with the water by repeated stirring indicate that more caustic-soda
solution is needed. In that case make up more caustic-soda solution
of the same strength and add it, not more than a pint at a time, and
with thorough stirring, until the desired effect is produced.

If an appropriate glass vessel for making tlie test is not at hand, a
little of the mixture may be taken between the fingers, then dip the
fingers under water and try to rub off the tar. It should leave the
fingers perfectly clean after a little rubbing with water. If an oily
coating remains, more caustic-soda solution is needed. Such an extra
addition of caustic soda will be required only in case of a very low-

1 Best done by previously determining by measurement the depth of 5 gallons of water
in the kettle. Set the kettle exactly level and mark the depth on a stick held vertically
on the center of the bottom.

8 farmers' BULLETTN 608.

^aatle chemical or a very hi<jrhly acid tar. The tar stock should be
kept in closed containers, .such as a pail with a friction top.

DILUTING THE DIP TO FORM A BATH.

Whatever the dip used, whether lx)iled dip, S-B dip. or a pro-
prietary preparation,^ certain facts must be borne in mind and a cer-
tain routine followed in preparing baths for dipping. .Ul concen-
trated arsenical preparations are considerably heavier than water,
and unless properly introduced into the dipping vat tend to make
their way to the bottom, after which it is difficult to get an even mix-
ture. In preparing a diluted bath it is necessary first to fill the vat
with water, leaving just enough space below the full water line for
the necessary volume of concentrated dip. Then the desired amount
of concentrated dip is to be poured in a thin stream evenly all over
the surface of the water — except, of course, at the shallow exit end
of the vat — after which a few minutes of brisk stirring will make
certain that the bath is of uniform strength throughout. If tar
stock is used, as in the case of the S-B dip, the tar stock is to be added
before the arsenic stock and may be put in when the vat is about
three-fourths filled with water. Tar stock should always be mixed
with two or three times its volume of water before being added to
the vat.

The dilutions at which the various concentrated stocks will be used
are as follows:

Boiled arsenic stock, containing either 8 pounds (low strength) or
10 pounds (high strength) white arsenic in 25 gallons, for the cor-
responding strength bath, 1 gallon added to every 19 gallons wat^r
(2^ pints to 5 gallons).

S-B arsenic stock, containing 10 pounds white arsenic in 5 gallons,
for low-strength bath 1 gallon added to ever}' 124 gallons wafer
(5^ fluid ounces to 5 gallons) ; for high-strength bath add 1 gallon
to every 99 gallons of water (04 fluid ounces to 5 gallons).

Tar stock, for both low-strength and high-strength baths, 1 gallon
added to every 300 gallons of finished bath (2 fluid ounces, or 4
tablespoonfuls, to 5 gallons). Mix the tar stock with two or tlireo
times its volume of water before adding to the vat. A certain lati-
tude in tlie amount of tar stock used is permissible, but it is believed
that the above pro|)ortions will be found most satisfactoiy.

REPLEMISHING THE BATH AND CORRECTING ITS STRENGTH.

As dipping jroes on, lh«^ Imth will uatunilly iieetl replenlBhinjt. In addition
lis Ktrenntli will pmbably need correc-tion from time to time. 'Vtrn cttuaeg which
may Ic.kI lu <lian>,'es in llic .stieiiKtli of arwinlcal batliH, tonelher willi luetliod.s

> It In VPi-y llkoly tlint till' l.iin'iui will Ihsuo pin-nilsalon for oortnln proprlrtary prepii
rations to bo iihmI In oITlrliil dlppInK'. Any such product will bpur a statemeiit ou tlio
label to till- i-ITcct tlint the prcliict Iiiih l.o.-n cMiiiiInod by tin- buroiiu nud has bcj-n por-
milted for use In olllclnl dipping id: ii ^Iven dilution.

AKSENICAL CATTLE DIPS. 9

of chemical analysis, have beeu elsewhere discussed by the writer,' Here it is
sufficient to note that even if all precautions are taken against leakage, either
in or out, against evaporation, and against mistakes In measurements, etc.,
still the bath is likely to change its strength owing to the action of micro-
organisms which grow therein in si:)ite of the presence of the poisonous arsenic.
As already mentioned, the active ingredient of the bath is an arsenite, either
of sodium or i)otassium. One species of microorganism is able»to take oxygen
from the air and to combine it with the arsenite, thus forming an arsenate, a
distinctly different compound of arsenic, and one which is much les^ poisonous
to ticks. This species of microorganism appears to flourish in nearly all dip-
ping baths under ordinary conditions of use and operates to gradually weaken
the bath. There is, however, another si^ecies of microorganism which occa-
sionally makes itself manifest in baths through which cattle are passed in ex-
ceptionally large numbers or at frequent intervals, and which operates in pre-
cisely the opposite manner, namely, to reduce any arsenate which may be
present to arsenite, thus rendering the bath stronger.

The chemical analysis of arsenical baths with sufficient accuracy for practi-
cal purposes is not a difficult matter. It does, however, require some chemical
training and equipment If State officials concerned with dipping can not
make provision for the execution of analyses, it should not be difficult to find
someone — physician, veterinarian, pharmacist, instructor in school or college,
or even a student — who. for a fee. which might be comparatively small if a
sufficient number of samples' from various sources could be counted on, would
find it worth while to undertake this work. It is desirable to have the
" actual arsenious oxid " — that is, the amount of arsenic existing as arsenite —
determined at least once a month, and the " total arsenious oxid " — that is,
the amount of arsenic existing as both arsenite and arsenate — determined at
least every two months. To avoid danger of poisoning cattle, it is safer to
discard the bath entirely whenever the "total arsenious oxid" would rise
above 0.25 per cent for the low-strength bath or above 0.30 per cent for the
high-strength bath after the bath had been adjusted to contain the proper
amount of " actual arsenious oxid."

In taking samples for analysis certain precautions are necessary. First,
the bath must be well stirred; next, the sample is filled at the vat side into
the bottle in which it is to be sent to the analyst. The bottle should hold not
less than 4 fluid ounces (one-fourth, pint) and should be filled up to the neck.
Unless the sample can be placed in the hands of the analyst in a very few
hours it should be treated with formaldehyde to preserve it from the action of
microorganisms which may affect the arsenic and which may work very rapidly
in the sample after its removal from a comparatively cool location under-
ground and exposure to hot summer weather. A little concentrated formalde-
hyde solution (37 per cent) may be cheaply obtained from the druggist, to-
gether with a medicine dropper. The formaldehyde is to be carefully added
to the sample with the medicine dropper, in the proportion of exactly .5 drop-s
to each 4 ounces of sample (20 drops to a pint). The bottle is then to be
immediately corked, the cork and lip of bottle wiped dry and completely
covered with melted sealing wax, rosin, or some similar material, in order to
exclude air. A few matches will furnish the heat necessary for melting the
sealing material. The analyst should be informed of exactly what steps were
taken in preparing the samples, and the latter should be shipped to him without
delay.

' 1 Department of Agriculture Bulletin 76.

10 FAKMERS' BULLETIN 603.

There are two methods of attacking the problems of rejilenishing
a bath and of correcting its strength — (1) method by weight and (2)
method by volume.

The method hy weight. — This method bases all calculations upon
the weight of white arsenic which actually is in the vat and the
weight which ought to be in the vat. Table 1 * gives the weight of
white arsenic which is actually present in baths of various volumes
and of varying percentages of arsenious oxid.

When the quantity of bath in the vat lies outside the range of the
figures given in Table 1 it will only be necessary to multiply or to
divide by 2. For example, if the bath amounts to 750 gallons it must
evidently hold only half as much arsenic as if it amounted to 1,500
gallons. If, on the other hand, it is desired to more accurately
employ figures which lie between those given in the table, either for
volume of bath or for percentage or weight of arsenic, it is only
necessary mentally to split the difference between the figures actually
given.

The manner in which Table 1 is used may be illustrated as follows :

Suppose one needs to replenish and correct a bath which is containetl in a
vat holding 1,500 gallons to the full water line. He finds that he has in the
vat 1,050 gallons of bath which his analyst informs him contains 0.14 per
cent actual arsenious oxid. Looking up these figures in the table, he finds
that they indicate 12^ pounds of arsenious oxid in the vat. What he wants is
a vat filled with solution of proper dipping strength, we will say, of the low-
strength formula. Now, the low-.strength formula calls for 0.19 per cent
actual arsenious oxid, and, as before stated, his vat holds 1,500 gallons to the*
full water line. Looking up these figures in the table, he finds that his vat
when filled with solution of proi^er strength must contain 23| pounds of
arsenious oxid. Therefore, in filling his vat to the full water line he must
introduce 23f less 12i pounds of white arsenic, or 11^ i>ounds.

Having found from Table 1 the weight of white arsenic necessary
to add to the vat, subsequent procedure depends upon the kind of
dip used. In the case of boiled dip prepared on the spot, it is
simply necessary to weigh out the proper amount of arsenic and to
boil it with the corresponding amount of sodium carbonate, water,
etc. In case the low-strength boiled arsenic stock is to be employed,
it is necessary to remember that it carries 1 pound of arsenious
oxid in every 3^ gallons. Therefore, multiply the number of pounds
of white arsenic needed by 3^ in order to find the number of gallons
of low-strength boiled arsenic stock to be added. In C4ise of the
S-B ar.senic stock, there is present 2 pounds of arsenious oxid in
every gallon. Therefore, divide the number of pounds of white
arseni(; desired by 2 in order to obtain the corresponding numlM?r of
gallons of S-B arsenic stock.

The high-strength lM)iled ai^senic stock, of course, carries 1 ])onnd
of white arsenic in each 2 A gallons.

1 Credit for this form of UI>1o 1b due (o Dr. G. A. Ilandloj', votorlnnry Inspector In this
burcuu.

ABSENIOAL CATTLE DIPS.

Table 1. — Table for finding pounds of ivhite arsenic in vat.

Liquid
in vat.

Per cent actual arsenious oxid in bath.

Gallons.
1,000....
1,050....
1,100„...
1,150....
1,200....
1,250....
1,300....
1,350....
1,400....
1,450....
1,500....
1,600....
1,700....
1,800....
1,900....
2,000....

Lbs.
10

m
11

Hi
12
12i
13

14
Hi
15
16
17
18

Lbs.

Hi
12

13
13J
14
Ui
15
15i
16i
17i
18i
191

21i

Lbs.
Hi

12f

14
14i
15
15i
16i

19f
21
22
231

Lbs.
14
14i
15i
16i
17

m
m

19
19i

211
22i
24
25J
26|
281

Lbs.
20f
21J
22f
24
25
26
27

1 This column may be taken as representing, nearly enough, correct weights of white arsenic for the low-
strength bath.
' This column represents correct weights of white arsenic for the high-strength bath.

The method by volume. — This method naturally applies only to
the use of stock solutions, not to cases where the desired amount of
white arsenic is to be weighed out and dissolved on the spot. The
facts needed to start on are exactly the same in both methods; that
is, one must know the capacity of the vat at the full water line, the
amount of bath actually in the vat, and its strength expressed as
per cent of actual arsenious oxid. The problem really resolves itself
into correcting the strength of the bath already in the vat, for when
this has been done it is simply necessary to fill up the remaining
space in the vat with bath of the regular strength. Calculations are
simplified by the use of Table 2.
Table 2.— Amount of arsenic stock necessary to correct each 100 yaUon.s bath.

Per cent actual

arsenious oxid

m bath.

For low-strength bath-

For high-strength bath-

Add low-
strength boiled
arsenic stock.

Add S-B
arsenic
stock.

Add high-
strength boUed
arsenic stock.

Add S-B
arsenic
stock.

Per cent.^

Qallons.

GaJhyns.

QaUons.

Gallons.

0.10

2.46

0.38

.11

2.18

.34

(')

.12

1.91

.29

2.62

0.50

.13

1.64

.25

2.40

.46

.14

1.36

.21

2.18

.42

.15

1.09

.17

1.96

.38

.16

.82

.13

1.74

.34

.17

.55

.08

1.53

.29

.18

.27

.04

1.31

.25

.19
.20
.21

1.09
.87
.65

.21
.17
.13

.22

.44

.08

.23

.22

.04

A bath less than half the desired strength should be discarded entirely.

12 farmers' bulletin 603.

To show the manner uf usiug Tiible ~, the same example may be taken as
served to illustrate Table 1, namely, a 1,500-gallon vat that contains 1,050
gallons of hath ;inaly7.iiig 0.14 per cent actual arseuious oxid. which is to be
brought to the full water line with standard low-strength bath. Supix)se
that low-strength boiled arsenic stock is to be employed. From Table 2 it
will be found that each ItJO gallons of 0.14 i>er cent bath requires 1.30 gallons
of low-strength boiled ar.senic stock to bring it to the right strength, so for
1,050 gallons there is needed 104X1.36=14.28 gallons of stock, which would
bring the whole volume to 1,050+14=1,064 gallons of proper strength bath.
There is then left 1.5<H)— 1,064=436 gallons of regular low-strength bath,
which must also be introduced to fill the vat, for which there is, of course,
needed 464-^-20' =23. 2 gallons of boiled arsenic stock. Now, 14.28+23.2=37.48,
or practically, S~i gallons of boiled arsenic stock altogether. Therefore water
will be run into the vat. about 6 quarts of tar stock being added during the
process as called for by the volume of fresh liquid iutroduce<l, finally leaving
just enough room below the full water line for 37i gallons of low-strength
boiled arsenic stock which is carefully measured in.

It appears not worth while to give a table for reducing baths if
they are found by analysis to be too strong. This event but seldom
occurs, and if it does the amount of water to be added may be easily
calculated. If, for example, a bath analyzes 0.25 per cent actual
arsenious oxid and is to be reduced to 0.19 per cent, then each 100
gallons should be diluted to make 100Xt|=131^ gallons — that is,
31^ gallons of water must be added to each 100 gallons of bath in
the vat.

OBTAINING THE CAPACITY OF A VAT.

To obtain the capacity of a dipping vat the following measure-
ments must be taken: (1) Length of the bottom; (2) width of the
bottom at its middle point; (3) length of water line; (4) width of
water line at its middle point; (5) vertical depth of dip at middle
of bottom — that is, at the same point where measurement No. 2 was
taken. For future reference it is Avell to mark this point on the side
of the vat. The measurements should be. carried to the nearest inch
for length, to the nearest half inch for depth, and to the nearest
(|uarter inch for width.

The measurements taken in feet and inches are now to be reduced
to feet and decimals of feet through Table 3.

1 See page 8.

ARSENICAL CATTLE DIPS.
Table 3. — Equivalents of linear inches and decimals of I foot.

Linear

Decimal

Linear

Decimal

Linear

Decimal

inches.

of 1 foot.

inches.

of 1 foot.

inches.

of 1 foot.

0.33

0.67

0.02

4i-

.36

.69

.04

.38

.71

.06

.40

.73

.08

.42

.75

.10

.44

.77

.13

.46

.79

.15

.48

.81

.17

.50

.83

.19

.52

lOi

.85

.21

.54

lOJ

.88

.23

.56

lOJ

.90

.25

.58

.92

.27

.60

.94

.29

, .63

.96

.31

.65

.98

There is an old, much-used rule for obtaining the capacity of a
dipping vat which, though somewhat inaccurate, possesses the marked
advantages of being easily grasped and, therefore, of not being liable
to error in its application and of being readily worked out inde-
pendently if partially forgotten. This approximate rule for present
purposes may be stated as follows: Multiply the average length hy
the average width., the product hy the depth., and this product hy 1\.^
The average length is of course obtained by adding the bottom length
to the water-line length and dividing the sum by 2; the average
width is obtained in the same manner.

The rule may be thus expressed as a formula :

to p length + bottom length top width + bottom width

- ^ ~— X Q X cleptu X •Y —

approximate gallons capacity.

As previously noted, the results given by this rule or formula are
not quite accurate. In fact, it does not account for the upper corners
of the vat at the exit incline, and so the vat really holds somewhat
more dip than thus calculated. The volume of this additional por-
tion of the vat may be easily calculated after the following correction
rule : Multiply half the difference of the lengths hy half the difference
of the widths, the product hy the depth., and this product hy 2^.*

Expressed as a formula the correction becomes :

X depth X 2^^

top length — bottom length top width — bottom width

_ . ^x 2

additional gallons capacity.

1 The precise figure is 7.48 ; that is, the number of gallons in one cubic foot.
= That is, by one-third of 7L Mathematically the correct order is to multiply by one-
third the depth, then by 7i. Practically, of course, the result is the same.

FABMEBS' BULLETIN 603.

This correction, added to the approximate volume first found, gives
the true capacity of the vat as nearly as it is possible to calculate it,
though if the vat is unevenly constructed, no formula can be entirely
accurate.

To illustrate the whole process of calculating the capacity of a vat, we will
suppose that a vat has been constructed after the plans and specifications of
the bureau elsewhere given. The measurements as taken, and as reduced to
decimals through the use of Table 3, are the following:

Reduced to
decimals.

Bottom length . . .
Bottom width . . .
Water-lme length
Water-line width.
Depth

12.0
1.5

22.8
2.71
5.25

In reducing to decimals, lengths need be carried only to the nearest tenth,
but width and depth should be carried out to hundredths. Throughout subse-
quent calculations an accuracy greater than 1 per cent is unnecessary, hence
decimal places should be cut off when multiplying so that each number multi-
plied, unless a whole number, shall contain not more than three figures.

Applying the approximate rule:

(1) (2) (3) (4) (5)

22.8 2.71 17.4 36.7 193

-fl2.0 +1-50 X 2.11 X5. 25 X 7^

2) 34. 8 2 ) 4. 21 36. 714 192. 675 1, 448 gallooB, approximate capacity.

17.4

2.11

Applying the correction :

(1)

22.8

-12.0

(2) (3) (4) (5)

2.71 5.4 3.29 17.3

L50 X .61 X5.25 X 2J

2 ) 10. 8 2 ) 1.21
5. 4 . 61

294 17. 2725 43. 3 gallons, correction.

The correct figure for the capacity of the vat is, therefore, 1.448+43=1,491
gallons.

CONSTRUCTING A MEASURING ROD FOR THE VAT.

In replenishing or strengthening dipping fluids it is frequently
necessary to ascertain just how many gallons of fluid are contained
in a partially filled vat. Taking the water-line measurements and
then calculating tlie contents is inconvenient and may sometimes
seriously dehiy dipping oi)erations. Therefore it is desirable to con-
struct a measuring rod Avhich will give directly the number of gallons
of li(iuid in tho vat at any time. Of course such a rod may bo grad-

ABSENICAL CATTLE DIPS, 15

uated by measuring successive known volumes of water into the vat
and marking on the rod the depth of each Imown volume, but in many
cases graduation through calculation may be more practicable.

The first step is to calculate the water-line measurements at half
depth and then at three-quarter depth. A little consideration will
show that the water-line measurements at half depth are exactly
half-way between the bottom measurements and the water-line meas-
urements of the completely filled vat; that is, they are the average of
these two measurements, obtained by adding them together and divid-
ing by two. In the same way the water-line measurements at three-
quarter depth are the average of the water-line measurements at
half depth and at full depth.

The second step is to calculate the capacity of the vat when filled
to three-quarter depth. Then, having prepared a straight, smooth
stick, 7 or 8 feet long and about 1^ inches square, lay off from one end
(marked " bottom ") the feet depth at the three-quarter level, and mark
the point with a pencil line, also adding the figure for gallons capac-
ity at that point.

Third, subtract the capacity at three-quarter depth from the capac-
ity at full depth, point back to the left two decimal places in the
remainder, and divide it into one- fourth of the actual full depth in
feet. The quotient is the average number of feet increase in depth
per 100 gallons liquid above the three-quarter level.

Fourth, subtract the actual capacity at the three-quarter level
from the next even 100 gallons above that level and set this figure
as the numerator of a fraction of which 100 is the denominator. By
this fraction multiply the figure for feet per 100 gallons, obtained in
the third operation. The product is the distance to be laid off on
the rod above the three-quarter depth point to obtain the level of
the next even 100 gallons above that point. By referring to Table
3, convert this distance to inches and lay it off on the rod with
proper notation. Now, having obtained this point for an even 100
gallons, it is only necessary to continue therefrom, marking off the
level of each succeeding 100 gallons by using the figxire obtained for
" depth per 100 gallons." The same figure can be used to obtain
capacities only a short distance below the three-quarter level with-
out serious error. But by a similar series of calculations it is pos-
sible to obtain the capacity at half depth, then the true average figure
for feet per 100 gallons between half depth and three-quarter depth,
and so to graduate the rod between those two levels.

The graduations are to be made permanent by saw cuts or notches,
50-gallon marks being interpolated if desired, and the corresponding
figures are cut into the wood.

FABMERS' BULLETIN 603.

Aa example may make the whole operatiou clearer. Taking the vat already,
used to illnsti-iite the method of obtaining total capacity (p. 14), we first makJ
the followiug table of dimensions: 1

Vat.

At full
depth.

At hall
depth.

At ihree-
quarier-
depth.

\V ater-Iine length

Feet.
22.8
2.71
12.0

Feet.

17.4
2.11

12.0
1.5
2.63

Feet.

Water-line width

2.4
12

Bottom length

Bottom width

Depth

5. -25

3.9

Second, we calculate the capacity at three-quarter depth (3.94 feet) to
956 gallojxs. From Table 3, 0.94 foot is found to be equal to lU inches; hencej
at 3 feet 11^ inches from the bottom end of the rod is made the mark for
capacity of 956 gallons.

Third, knowing the full capacity to be 1,491 gallons; 1,491—956=535 gallons!
or 5.35 hundreds of gallons space in the vat between the three-quarter and fullj
depth le,v;.o, which corresponds to 5.25-^-4=1.31 feet difference in depth]
1.31-^5.35=0.245 foot per 100 gallons.

Fourth, 1,000—956=44 gallons'. ^ X0.245=0.108 foot, corresponding to
gallons. From Table 3. 0.108 foot=li inches (nearly), so on the rod li inchc
above the mark for 956 gallons is made a mark for 1,000 gallons. Then, fron|
the 1,000 gallons mark is measured off 0.245 foot=3 inches for 1,100 gallons J
2X0.245=0.49 foot=6 inches for 1,200 gallons, etc.

The graduations necessarily depart a little, though not much, frod
the true points for levels between the fixed points established by cal^
culation. One may, if familiar with the process of " plotting," laj
off these fixed points from depths on one axis and capacities on the
other, and so construct the " curve " of the capacity of the vat.

THE SAFE DISPOSAL OF WASTE ARSENICAL BATHS.

Previous publications of the department have advised that whei
vats are emptied for cleaning, the waste dip should not be flowed ovei
land or vegetation to which domestic animals have access, or froi
whence it may find its way into water supplies, but should preferablvl
be run into a properly located pit protected by a fence.

Dalrymple and Kerr^ have proposed to add slaked lime and copj
peras to waste dip in the vat in order to throw down arsenic in ai
insoluble form, thus allowing the overlying liquid, after settling, tc
be disposed of as if arsenic free. The method retiuires very thor-j
ough stirring in order that the difficultly soluble lime may produce
the desired effect. Wliether the necessary stirring can be accom^
plished in large vats with sufficient thoroughness to render tht
method reliable under practical conditions on a large scale may be
(luestionable.

'Bulletin 132, Louisiana .\KrlculturaI Experiment Station, 1911
discrlptlon of the nii'tliod is ii\vcn in Fnrnifrs" Bulletin 408 and li
Industry Circular 207 of the T'. S. Department of .VKrUullurc

A brief detnlle<3
Rureau of .\Qimal

W A. S II INC TON : GOVEH.SMK.VT TKINTING OmCB : 1014

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