rths filled with water, and stir thoroughly.

All the utensils must be free from greasy or oily matter which would coat
the arsenic and hinder its solution. The operation of boiling requires
constant attention to avoid loss by foaming. Hard water may be used, but in
that case considerable undissolved material, which, however, does not
contain any arsenic, may be left after boiling.

For a stock solution to be kept on hand and used when needed add no tar,
but after the solution has become cold make it up to 25 gallons, stir well,
let settle, and draw off into containers which can be well closed. In this
case the tar stock previously described is also required.

_Diluting the dip._--First run water into the vat about three-fourths up to
the dipping line, at which its capacity must be known. If tar stock is to
be used the necessary amount will be one-third of a gallon for every 100
gallons of vat capacity. Measure it out, mix it with 2 or 3 times its
volume of water and pour it along the surface of the water in the vat,
stirring a little.

Every 100 gallons of standard-strength bath calls for 1-3/5 pounds white
arsenic, which quantity is contained in four-fifths of a gallon of S-B
stock or in 5 gallons of boiled stock. From these figures the quantity of
arsenic or stock needed to charge the vat may be calculated. Or one may
base the calculation on the following facts:

One pound of white arsenic will make 62-1/2 gallons of bath.
One gallon of S-B stock will make 125 gallons of bath.
One gallon of boiled arsenic stock will make 20 gallons of bath.

All solutions of arsenic are considerably heavier than water and if
carelessly put into the vat they may plunge to the bottom and be difficult
to mix. Therefore always pour the arsenic stock or a proprietary dip in a
thin stream evenly along the vat except at the shallow exit end. Another
precaution to be taken in handling proprietary dips is never to mix them
first with small quantities of water, which may "break" them. Pour them
directly into the water in the vat.

Finally, add water up to the dipping line and stir well. An excellent way
to stir is by a pail tied to a rope. Sink it at the entrance end of the vat
and haul it along the bottom to the exit. Then raise it, throw it back to
the entrance end, and haul through again, repeating as many times as
necessary but always hauling through in the same direction.

The standard-strength bath prepared as ab