104 VETERINARY STUDIES 



mixes well with soft water, and fairly well with ordinary water. 

 This is used in 2 to 3 per cent solution or about 4 ounces per 

 gallon. It is much cheaper and more efficient than carbolic 

 acid and a thoroughly reliable and useful disinfectant. 



Proprietary coal tar products. — There is a long list of coal 

 tar products. They are similar to compound cresol, and are 

 usually reliable when approved by the federal Bureau of Animal 

 Industry and used in the approved strength. 



Formalin. — Formalin is a very important disinfectant, either 

 as a liquid or vapor. It is active and reliable, when properly 

 used and does not injure paint or metals. It is in the market 

 as a 40 per cent solution of formaldehyd gas. The odor is irri- 

 tating and disagreeable, somewhat resembling chlorin. Forma- 

 lin is apparently more active in the presence of moisture. For 

 use in vapor form, at least 20 ounces per 1000 cubic feet should 

 be introduced rapidly into a tight room. 



Formalin may be vaporized very satisfactorily by combination 

 with permanganate of potash in powder or fine crystals, in the 

 proportion of 16 ounces of permanganate and 20 ounces forma- 

 lin for each 1000 cubic feet of air when the inside temperature 

 is 65 degrees F. or above. Use one fourth to one half more of 

 the disinfectants for lower temperatures. A large flaring tin 

 pail is used for each such mixtiire. The permangcmate should 

 he put in first. 



The building must be made tight. Strips of wet newspaper 

 do very well for cracks and small holes. Leave the building 

 closed for at least six hours, with no inflammable material in 

 the room close to the outfit. This method is applicable only to 

 small tight buildings. At low temperatures, it is unreliable. 



Heat. — Fire is the most reliable disinfectant, and the one that 

 should invariably be used where an article is to be destroyed. 

 Moist heat is more active and reliable than dry heat at the same 

 temperature. Boiling for an hour is probably sufficient to de- 

 stroy or render harmless any known disease producing germs. 



Corrosive sublimate. — This is sold in the form of white crys- 

 tals or powder. It dissolves in about 16 parts of water, and its 

 solubility can be increased by muratic acid or iodide of potash. 

 It is disinfectant in the proportion of 1 to 2000, about dy 2 grains 

 to a pint of water, and in even more dilute solution. A con- 

 venient solution can be made by dissolving it in alcohol, 1 to 8. 

 A teaspoonful of this to a quart of water gives about 1 to 2000 



