88 VETEEINAEY HYGIENE 



If turbidity appears in a 6-oz. bottle with half an ounce 

 of lime water, the amount of carbonic acid in the air is 

 about 1-1 parts per thousand. With a lOJ-oz. bottle the 

 amount is "62 per 1,000 ; if a 151-oz. bottle '42 per 1,000. 



The bottles should be first filled with water, then emptied 

 in the place where the sample of air is being examined, the 

 lime water at once added, the bottle securely stoppered and 

 well shaken. Angus Smith recommends ten or more 

 bottles to be employed, and a table constructed from the 

 above data of the indications of the amount of COg each 

 represents. 



Another method adopted by Dr. Angus Smith for rapidly 

 determining carbonic acid is by aspirating into a double- 

 necked bottle, by means of a rubber ball, a known volume 

 of air. The bottle contains a solution of baryta, and the 

 process is at an end when the turbidity is such that a 

 paper with writing on it can no longer be read when looked 

 at through the base of the flask. A scale is given showing 

 the volumes of COj per 1,000 volumes of air for each 

 aspiration of the ball. 



The simplest method in the absence of this graduated 

 apparatus would be to use an ordinary rubber syringe as 

 an aspirator, and perform two experiments, one in the 

 outside air and one in the stable ; the impurity of the 

 latter would thus be readily arrived at. 



It is most important to bear in mind in employing the 

 lime or baryta test for carbonic acid, that samples of air 

 are not selected near the stable floor. Owing to the 

 presence of ammonia the alkalinity of the lime or baryta 

 water is increased, and fictitious purity of air thus obtained. 



Samples should be selected four to six feet above the 

 ground. 



Determination of Organic Matter. — A known volume of 

 air, say 12 cubic feet, is slowly drawn through distilled 

 water by means of an aspirator. The water is then sub- 

 mitted to the free and albuminoid ammonia process, 

 which can only be carried out by an expert ; it becomes in 

 fact a water analysis. 



Digitized by Microsoft® 



