432 EXTERNAL PARASITES OF ANIMALS 



brought to a boil. The sodium carbonate is then added and dissolved 

 by stirring. When this is accomplished, the arsenic is added and 

 dissolved in a similar manner. The fire is then drawn and the pine tar 

 added slowly in a thin stream and thoroughly mixed with the dip by 

 constant stirring. This strong stock solution is diluted to 500 gallons 

 before using. 



The diluted arsenical solution may be left in the vat and used re- 

 peatedly, replenishing with the proper quantities of water and stock 

 solution when necessary. When not in use, the vat should be tightly 

 covered with a waterproof cover to prevent evaporation on the one 

 hand and further dilution by rain on the other hand. Securely cov- 

 ering the vat when not in use also lessens the risk of accidental poison- 

 ing of stock and human beings. 



On account of the fact that arsenic is a dangerous poison, great care 

 must be observed in making and using the arsenical dip. From the 

 time the arsenic is procured from the druggist until the last particle 

 of unused residue is properly disposed of, the most scrupulous care 

 should be taken in handling this poison. Guessing at weights or 

 measures or carelessness in any particular is liable to result in great 

 damage, and not only may valuable live-stock be destroyed, but human 

 beings may lose their lives as well. 



In the use of arsenical dips care should be taken not only to avoid 

 swallowing any of the dip, but persons using the dip should also bear 

 in mind the possibility of absorbing arsenic through cuts, scratches, or 

 abrasions of the skin, and the possibility of absorbing arsenic by in- 

 halation of vapors from the boiler in which the dip is prepared or by 

 the inhalation of the finely divided spray when the spray pump is used. 

 It should be remembered that the absorption of even very small quan- 

 tities of arsenic, if repeated from day to day, is liable ultimately to re- 

 sult in arsenical poisoning. 



Cattle should always be watered a short time before they are dipped. 

 After they emerge from the vat they should be kept on a draining-floor 

 until the dip ceases to run from their bodies ; then they should be placed 

 in a yard free of vegetation until they are entirely dry. If cattle are 

 allowed to drain in places where pools of dip collect, from which they 

 may drink, or are turned at once on the pasture, where the dip will 

 run from their bodies on the grass and other vegetation, serious losses 

 are liable to result. Crowding the animals before they are dry should 



