16 BULLETIN 898, U. S. DEPARTMENT OF AGRICULTURE. 
due to the fact that on exposure to air, turpentine slowly absorbs 
oxygen and becomes slightly acid, causing corrosion of the iron, 
which goes into solution, bringing about the ee of the a 
or brown color. 
Unless the iron is protected against the action of the acids formed 
when the tank has been eal and is full of air with a thin filmt ay 
of turpentine on the inner surface, tank cars in regular use for trans- 
pom turpentine soon become rusty inside. As ordinary paint, 
made from linseed oil and turpentine, will not resist the solvent action 
of turpentine, it is necessary to use a pamt made from materials 
which are not affected by turpentine. One made according to the - 
following formula, which makes about 8 gallons, enough to give an 
8,000-gallon tank two coats, is generally used for this purpose. | 
Wood. or’ denatured alcohol (gallons)_-- =-_.. 2 ee 5 
Orange shellac (pure) (pounds)= 2222-2. 2. ise eee ee 24 
Dry. redlead (pounds)=...4... 323 a eee eee 24 | 
Veniee turpentine (ounces): 2-2 =< cescc 6 ee 28 m 
Dissolve the shellac in the alcohol. This operation, which takes 
some little time, is best done by putting the two in a can and allowing 
the mixture to stand, covered, for two or three days, stirring occasion- 
ally. After all the shellac has gone into solution, strain the liquid 
through cheesecloth to remove any insolubie matter. Then warm 
the Venice turpentine until it flows freely and stir it into the shellac 
solution. This is now ready for use in making up the paint. When 
ready to use the paint, immediately before it is to be applied to the 
tank, from which all loose rust has been scraped or removed with a 
wire brush, mix the red lead with the liquid, being sure to stir thor- 
oughly to break up all lumps. Apply with an ordinary paint brush 
to the thoroughly clean and dry surface. Brush the paint out well »— 
to prevent peeling. Allow the first coat to dry hard before applying 
the second coat. 
Caution.—W hen painting the inside of a tank with this prepara- 
tion, or whenever it is necessary for a man to enter a tank which has 
held turpentine, some arrangement must be made to prevent inhala- 
tion of the alcohol or turpentine fumes. A supply of fresh air can 
be pumped in to the workman through a pipe connected with either 
an air pump or a small blower like those connected with small port- - 
able forges. A gas mask with a container filled with broken pumice 
stone saturated with concentrated sulphuric acid, through which the 
air is drawn, may also be used. The absorption fees must be 
recharged at least once a day. The pumice, in pieces about the size 
of a pea, should be steeped in the acid and the excess acid allowed 
to drain off before being placed in the container. Since concentrated 
sulphuric acid rapidly absorbs moisture from the air, thus losing its 
absorptive qualities, the acid supply and the pumice after saturation 
