LICE 289 



tage of this system is that if hogs are thus sprayed in 

 their sleeping cots these places are also freed from lice. 



Kerosene emulsion usually contains from 5 to 10 per 

 cent of kerosene. Since oil and water do not mix very 

 readily, care must be taken as to how this is prepared. 

 One way to make kerosene emulsion is to take one-half 

 pound of hard soap and dissolve it in one gallon of hot 

 water and then add two gallons of a cheap grade of kero- 

 sene. With a high grade of oil a smaller quantity will 

 suffice. This should then be thoroughly emulsified, or 

 mixed, which is probably done the best by means of the 

 spray pump just mentioned. The pump set into the 

 bucket containing the hard soap, water and kerosene, may 

 be worked and by turning the nozzle back into the bucket 

 thoroughly mix the solution. After being thoroughly 

 mixed in this way, the hard soap tends to keep the oil in 

 suspension, then seven gallons of water should be added 

 and the whole again well mixed ; it is then ready for use. 



The Dipping Tank. — One of the best methods of de- 

 stroying lice is by means of the dipping tank. The cut (36) 

 shows this piece of apparatus as in use at the Illinois Ex- 

 periment Station farm. Various solutions may be used 

 in this as well as by the other means- of destroying lice. 

 Coal tar dips are frequently used and are quite eflEective, 

 but not always so. They have a tendency to destroy the 

 greater part of the lice, or at least drive them away, but 

 they do not destroy the nits. It is necessary therefore to 

 dip a second time about ten days after the first dip to de- 

 stroy the lice hatched from the nits, and in practice it is 

 found that if hogs are to be kept free from lice with coal 

 tar dips they must be used frequently. It has also been 

 found on different occasions that hog lice may be given a 

 bath in a solution of the coal tar dips and not be seriously 



