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 si^IasMug. Hence never work hurriedly ; 

 stir deliberately and regularly; do not dump in the arsenic and sal soda, but 

 carefully sUde 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 paddle 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- 

 dleiinto 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 tJie 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 vers^ low- 



1 Best done by previously determining by measurement the deptti 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. 



