14 days after the first. The second treatment is
necessary to kill the few parasites which sometimes escape at the first
treatment, either in the egg stage or as fecundated females.

[Illustration: FIG. 11.--Mite which causes psoroptic scab of sheep.
Enlarged about 100 times. The mite of psoroptic cattle mange is almost
identical in appearance.]

LIME-SULPHUR DIP.

The lime-sulphur dip is made in the proportion of 12 pounds of unslaked
lime (or 16 pounds of commercial hydrated lime--not air-slaked lime), 24
pounds of flowers of sulphur, and 100 gallons of water.

_Directions for preparing 100 gallons of dip._--Weigh out the lime, 12
pounds (or hydrated lime, 16 pounds), and sulphur, 24 pounds. Place the
unslaked lime in a shallow, water-tight box similar to a mortar box, or
some other suitable vessel, and add water enough to slake the lime and form
a lime paste or lime putty. Sift into this paste the flowers of sulphur and
stir well; then place the lime-sulphur paste in a kettle, boiler, or tank
containing 30 gallons of water, the water being first heated nearly to the
boiling point. Boil the mixture for two hours at least, stirring
frequently; add water occasionally to maintain the original quantity. Allow
the mixture to settle in the tank or draw the entire contents of the kettle
or boiling tank into a large tub or barrel placed near the dipping vat and
provided with a bunghole about 4 inches from the bottom, and then allow
ample time to settle--from two to three hours or more if necessary. When
fully settled, draw off the clear liquid into the dipping vat, taking care
not to allow any of the sediment to accompany it, as the sediment is liable
to render the dip unnecessarily caustic. The clear liquid thus obtained
requires only the addition of sufficient clear warm water to bring the
total up to 100 gallons. Flowers of sulphur must be used and the lime must
be of good quality.

The dipping bath should be used at a temperature of 100 deg. to 105 deg. F., and
for official dippings must be maintained at all times at a strength of not
less than 2 per cent of "sulphid sulphur" as indicated by the Bureau of
Animal Industry field test for lime-sulphur baths.

NICOTIN DIP.

The nicotin dip is made with sufficient extract of tobacco, or nicotin
solution, to give a mixture containing not less than five one-hundredths of
1 per cent nicotin and 2 per cent flowers of sulphur. Sufficient nicotin
would therefore be