Cattle-Fever Ticks. 25 



Arsenic stock requites the following materials ready to hand 



before starting: 



Pounds. ' 



Caustic soda 4 



White arsenic 10 



Sal-soda crystals 10 



There should be also some means for heating the solution in case, 

 as sometimes happens because of impure materials, lack of skill, or 

 some unforeseen circumstance, the heat created by mixing the ma- 

 terials should be insufficient to dissolve all the arsenic. 



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 the 

 arsenic in fast enough to keep the solution very hot — nearly but not 

 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 crys- 

 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 dissolved. 



Cautions: It is necessary to avoid splashing. Hence never work huiTiedly; 

 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. 



1 The chemicals employed have no effect upon iron. They will, however, actively cor- 

 rode zinc, tin, or solder ; hence a soldered pail must be watched for leaks and is far 

 inferior to a seamless pail, stamped from a single sheet of iron. A tinned pail is pre- 

 ferred to a galvanized one, but a plain iron seamless pail or an iron kettle should be 

 obtained if possible. 



~ 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 



■> the center of the bottom. 



