600 IOWA DEPARTMENT OF AGRICULTURE 



the gallon and the resulting solution is applied directly to surfaces of 

 substances which are to be disinfected. 



Formaldehyde gas is in most cases impracticable for stable disinfection. 

 Where, however, can be made almost air tight, and the animals removed, 

 it will be found very serviceable, as it penetrates every crevice. 



Several methods are in vogue for disinfecting with formaldehyde gas. 

 Probably one of the most simple and practical methods of liberating such 

 gas is by means of the chemical reaction which takes place when for- 

 malin is poured upon permanganate of potassium. For each 1,000 cubic 

 feet of air space 16 2-3 ounces of crystallized of powdered permanganate 

 of potassium is placed in a wide-surfaced pan; 20 ounces of formalin is 

 then poured upon it, and the room immediately closed for a period of 12 

 hours or longer. This method is efficient only when it is possible to seal 

 tightly the rooms or compartments to be disinfected and when their tem- 

 perature is not below 50 degrees F. 



CARBOLIC ACID. 



Carbolic acid in its pure form is, at ordinary temperatures, in the 

 shape of long, white crystals. For convenience it is frequently dispensed 

 in liquid form by the addition of 10 per cent of water. A 5 per cent so- 

 lution of caibolic acid is sometimes used as a disinfectant, but carbolic 

 acid has the disadvantage of being expensive and somewhat difficult to 

 dissolve. ,^,.. .._.^! 



CBUDE CAEBOLIC ACID. 



This substance should not be confused with pure carbolic acid. It is 

 a product of coal-tar dis;i'.lation and conssts for the most part of practic- 

 ally inert oils and cresylic acid. Its disinfecting power depends upon the 

 amount of cresylic acid which it contains, as well as the relative percentage 

 of hydrocarbon oils. Owing to its uncertain composition crude carbolic 

 acid can not be classed as one of the most desirable disinfectants. 



CEESOL. 



Cresol, commonly termed "straw-colored carbolic acid," "liquid carbolic 

 acid," etc., in a 2 per cent solution is an efficient disinfectant. It has the 

 disadvantage, however, of being somewhat difficult to dissolve, so in pre- 

 paring a disinfecting solution warm water should be used and care ex- 

 ercised that the drug is entirely dissolved. As the disinfecting power of 

 cresol is dependent upon the amount of cresylic acid contained therein, 

 it is essential when using the drug to know the degree of purity. Grades 

 can be purchased under a guaranty to contain from 90 to S3S per cent of 

 cresylic acid. Any containing less than 90 per cent should be rejected. 



COMPOUND SOLUTION OF CEESOL. 



Compound solution of cresol (liquor cresolis compositus), now recog- 

 nized by the United States Pharmacopoeia as an official preparation, is 

 composed of equal parts of cresol (U. S. P.) and linseed oil-potash soap. 

 It is an efficient disinfectant in a 4 per cent solution and has the ad- 

 vantage of mixing readily with water. 



