78 OHIO EXPERIMENT STATION: BULLETIN 356 



sheep dip, properly mixed and intelligently handled, is cheap, quick 

 and effective and is the method in general use in this country. 



The dip used and the methods of applying it vary in different 

 parts of the country. For small flocks, a tub or vat large enough to 

 hold a sufficient amount of the solution to completely immerse the 

 sheep, may be used. The required amount of water may be heated 

 in one or two capacious kettles. Where hundreds of sheep are to be 

 treated, especially prepared dipping pens, vats and draining pens 

 and large boilers for heating the water are necessary. 



Effective dips contain certain ingredients which are poisonous 

 to the parasite. These ingredients may also, if used in too concen- 

 trated a solution, be poisonous to the sheep. But this danger may 

 be avoided by preparing the dip as directed by the manufacturer 

 and maintaining the recommended strength throughout the dipping 

 operations. In addition to the poisonous constituent, the dip may 

 contain other elements, as water to dilute and dissolve the poison ; 

 also such substances as alum or potash to make the poison more 

 readily soluble or miscible with water. 



The chief poisons used in the various dips are tobacco, arsenic, 

 sulphur and lime, coal-tar oils and cresylic acid. Any one of the 

 dips containing these poisons, when correctly made, intelligently 

 diluted and properly applied, is effective. Each has its advantages 

 and disadvantages. For scab, lime-sulphur, tobacco and arsenic 

 dips are usually recommended. For lice and the so-called sheep 

 ticks, tobacco, coal-tar creosote and cresylic acid dips are commonly 

 recommended. 



COAL-TAR CREOSOTE DIPS 



The coal-tar creosote dips appear on the market under a be- 

 wildering number of trade names. They are made from coal-tar 

 derivatives. Creosote oil is the name given to the principal ingre- 

 dient. This oil is made soluble or miscible in water by means of 

 soap. 



Chemists of the U. S. Department of Agriculture have deter- 

 mined that in order to be effective, these dips should contain, when 

 diluted and ready for use, not less than 1 percent by weight of coal- 

 tar oils and cresylic acid combined. In no case should the diluted 

 dip contain more than four-tenths of 1 percent nor less than bife- 

 tenth of 1 percent of the cresylic acid ; but when the proportion of 

 cresylic acid falls below two-tenths of 1 percent, the coal-tar oils 

 should be increased sufficiently to bring the total of the coal-tar and 

 the cresylic acid in the diluted dip up to 1.2 percent by weight. 



Lack of a practical field test for determining the extent of 

 deterioration of the coal-tar creosote dips makes the task of re- 



