14 FARMERS' BULLETIN 909. 



much exercise or overheating shortly after dipping, especially if 

 arsenical dip or oil is used. 



The dip in the vat should be changed as soon as it becomes filthy, 

 regardless of the number of animals that may have been dipped in 

 it. In cleaning the vat the entire contents should be removed, 

 including all sediment and foreign matter. 



DIPS FOR CATTLE LICE. 



In choosing a dip for cattle lice the conditions under which it is 

 to be used should be considered. If the dipping plant is supplied 

 with soft water, any of the dips recommended for lice may be used ; 

 but if the water is very hard the dip that mixes best with the water 

 available should be selected. The arsenical dip mixes well and may 

 be used in hard waters without injury to the animals from that cause. 

 The nicotin dips also are suitable for use in any reasonably good 

 water. While the coal-tar % creosote dips when used in soft water 

 are very effective against lice, they sometimes injure the animals 

 when used in some of the hard waters. Before using coal-tar creosote 

 dips with hard or alkaline water the following test should be made 

 to learn whether a separation occurs in such water : In a clean bottle 

 or jar of clear glass place a measured quantity of dip and pour in, 

 with thorough mixing, the desired quantity of water, preferably 

 warm, which should be added in approximately the proportion to 

 be used in dipping. If after standing for one hour an oily layer 

 or a mass of globules appears either at the top or at the bottom of 

 the liquid, the dip should not be used with that kind of water. This 

 simple test for the coal-tar creosote dips may often prevent loss. 

 Death losses, however, may occur even when there is no apparent 

 separation of the diluted dip tested by this method. 



None of the dips tried in the bureau's investigations can be de- 

 pended upon to eradicate all cattle lice with one dipping, but any of 

 those described in the following pages will generally eradicate lice 

 if the cattle are given two dippings 15 to 16 days apart. 



ARSENICAL DIPS. 



Arsenical dip has been used to a considerable extent for lice and it 

 has proved to be a very satisfactory remedy. The formula for mak- 

 ing 500 gallons of arsenical dip is as follows. 1 



4 pounds caustic soda (85 per cent pure). 



8 pounds white arsenic (99 per cent pure), in fine powder. 



8 pounds sal soda crystals. 



1 gallon pine tar. 



Water sufficient to make 500 gallons. 



1 For fuller information relative to arsenical dip see Farmers' Bulletin No. 603. 



