DISEASES OF CATTLE 43 



lection and preparation of the disinfectant. The fact must not be 

 overlooked that many agents used for the destruction of bacteria are 

 likewise poisonous to animals and man. In fact, some drugs, al- 

 though powerful as germicides, are so poisonous as to preclude their 

 general use in the work of disinfection. Among such, as previously 

 stated, is bichlorid of mercury, which possesses the power of destroy- 

 ing not only bacteria, but spores as well. It is therefore essential in 

 deciding upon an agent to select one having a known germicidal 

 strength, properties of solubility, and at the same time possessing a 

 reasonable degree of safety to animals and man. 



All things considered, it is probable that some of the coal-tar 

 products best fulfill these requirements. In this class is the com- 

 pound solution of cresol, already mentioned, a preparation recog- 

 nized as official by the United States Pharmacopoeia and known as 

 liquor cresolis compositus (U. S. P.). This preparation mixes read- 

 ily with water and will prove a very efficient disinfectant. It should: 

 be used in the proportion of 4 or 5 ounces to each gallon of water. 



Another favorable agent is cresol (commercially known as 

 liquid carbolic acid). It is not as soluble as liquor cresolis com- 

 positus and should be thoroughly stirred during the process of mix- 

 ing, which will be facilitated by using hot water. It is advisable to 

 secure a grade of the drug with a guaranty of 95 per cent pure, and 

 such should be used in the proportion of 2 or 3 ounces to a gallon 

 of water. 



As an accessory preparation and for use after the application 

 of the disinfectant it may be advisable to make ready a lime wash 

 to each gallon of which there has been added 4 ounces of chlorid of 

 lime, or if it appears desirable to use the disinfectant and lime wash 

 at one application, the following method may be followed in prepar- 

 ing 5 gallons: Slake 7 l /2 pounds of lime, using hot water if neces- 

 sary to start action. Mix to a creamy consistency with water. Stir 

 in 15 fluid ounces of cresol (commercially known as liquid carbolic 

 acid) at least 95 per cent pure, and make up to 5 gallons by adding 

 water. In case compound solution of cresol (liquor cresolis com- 

 positus) is 'used, add 30 fluid ounces instead of 15 as in the case of 

 cresol (liquid carbolic acid). Stir thoroughly. If to be applied 

 through a spray nozzle, strain through a cloth or very fine wire 

 sieve. Stir frequently when applying and keep covered when not in 

 use. In case a large surface is to be disinfected it will be advisable 

 to prepare a liberal amount of the disinfecting solution before be- 

 ginning the application. Such solutions, however, should not be 

 permitted to remain in receptacles which are accessible to animals. 



Method of Application. The efficacy and economy of the 

 work will depend in a great measure upon the method of applying 

 the disinfectant. Economy requires that the disinfecting solution 

 be applied rapidly ; efficiency requires that it be not only spread in 

 such manner as to cover the entire surface requiring disinfection, 

 but that sufficient quantity and force be used to drive the solution 

 into all cracks and crevices. 



