﻿2 METHODS FOR THE DETERMINATION OF 



took advantage of the process devised by Wankljn, Chapman, and 

 Smith ^ for the estimation of organic matter in water by its conversion 

 into free and albuminoid ammonia, and adapted it to the estimation of 

 organic matter in air. He aspirated the air through cotton- wool, or 

 through gun-cotton, asbestos, or pumice-stone, and then subjected the 

 absorbent to distillation, thereby converting the organic matter derived 

 from the air into ammonia. He found that aspiration through asbestos 

 gave the most reliable results. 



Moss * passed a measured quantity of air through four wash bottles 

 of 100 C.C. capacity, each containing 50 c.c. of pure distilled water, ex- 

 cept the first, which contained also 50 c.c. of pure hydrochloric acid. 

 The absorbent solutions are then subjected to distillation and the 

 ammonia evolved from the organic matter estimated with Nessler's 

 reagent. 



R. Angus Smith ^ aspirated measured volumes of air through pure 

 distilled water contained in an absorption tube. The water is then 

 subjected to distillation and the ammonia estimated by means of 

 Nessler's reagent. 



The method employed at the Montsouris ^ Observatory, near Paris, 

 consists in drawing a known volume of air through bent tubes or 

 through a "rose," laid in a cooling mixture. The suspended particles 

 in the air are condensed and retained, and are then taken up with pure 

 distilled water ; or in addition to the cooling mixture the air is con- 

 ducted through pure distilled water. The distilled water containing 

 the suspended matter from the air is then subjected to distillation and 

 the ammonia estimated by means of Nessler's reagent. 



In the laboratory of the Medical Officer of Health,^ in Glasgow, the 

 apparatus employed at the Montsouris Observatory is slightly modi- 

 fied. The air is drawn through a " rose " which is placed in a small 

 vessel containing a quantity of small glass beads lying in dilute sul- 

 phuric acid. The sulphuric acid and beads are then transferred to a 

 clean retort, the acid is neutralized with solution of sodium carbonate, 

 when the estimation of ammonia is conducted in the usual manner. 



Fodor^ uses two U-shaped tubes containing pure distilled water 

 acidulated with sulphuric acid. The air is filtered through glass-wool 

 and the amount of organic matter in the dust is determined by distilla- 

 tion, as well as the amount contained in the acidulated water. The 

 two absorbents are subjected to distillation separately, thus showing 

 the amount of organic matter in each of them. 



Lehmann ' recommends Uff elmann's method in which the air is aspi- 

 rated through two small flasks, the one containing a dilute solution of 

 sulphuric acid and the other a dilute solution of caustic potash, each 

 of about one per cent, strength. These solutions are then mixed and 



