The Conquest of the Desert 



Hunter, determined not merely to think but 

 also to experiment. He did not assume that 

 cattle could only be dipped once a fortnight, 

 but set to work to find out how often, without 

 injury, they might be dipped so as to destroy 

 all the ticks. He proposed to discover the 

 correct composition of the dipping fluid so as 

 to secure (1) safety in the use and (2) destruc- 

 tive effect. His first task was to test by 

 practical experiment the action of all the best- 

 known dips on the market. Finding some of 

 them injurious, and none entirely satisfactory 

 when used at short intervals, he evolved the 

 now well-known laboratory dip, sometimes 

 called the " short-interval " or " three-day 

 dip." This dip can be used every seventy- 

 two hours with no ill effects to the animal, 

 and with the complete destruction of all ticks. 

 He further showed that with frequent dipping 

 the skin of an animal becomes temporarily 

 impregnated with arsenic so much as to render 

 the beast poisonous to any ticks which may 

 become attached to it during the intervals 

 between the successive dippings. That is to 

 say, a newly dipped ox may destroy of its own 

 accord a large number of ticks apart from those 

 actually killed in the dipping tank. He proved 



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