﻿ORGANIC MATTER IK AIR. 6 



the oxidizable matter determined by distillation and testing with 

 ^N'essler's reagent. 



A modification of Chapman's method which has met with consider- 

 able favor consists in the aspiration of a known volume of air through 

 freshly ignited finely granular pumice-stone contained in a narrow ab- 

 sorption tube. The subsequent treatment of the pumice-stone is similar 

 to that first employed by Chapman. This method was devised by 

 Professor Kemsen ^° and has since been used by Miss Talbot^' and 

 by Dr. Abbott.'" 



Smee " employs a large glass funnel, sealed at the neck, and filled 

 with cracked ice. The moisture and suspended particles in the air are 

 <3ondensed on the exterior surface of the funnel and are collected in a 

 small beaker placed underneath the funnel. The condensations are 

 then subjected to distillation and the ammonia estimated by means of 

 ^essler's reagent. 



Fox'" prefers what he calls the "pulverization of water method." 

 It consists in bringing consecutive portions of fresh air into intimate 

 contact with a small quantity of very pure water which is being reduced 

 to a minute state of subdivision by pulverization in a glass cylinder 

 about eight inches in length and two inches in diameter, and which is 

 iurnished with a large india-rubber stopper. This stopper has two 

 perforations, into one of which the air pipe of a Bergson's spray pro- 

 ducer is fitted ; the other is intended for the passage of a straight glass 

 tube about twelve inches long and one-fourth inch in diameter. Thirty 

 ■cubic centimetres of pure distilled water are placed in the cylinder, and 

 this serves to wash the air of all its impurities as it passes through the 

 fine spray formed in the cylinder by the spray -producer. The thirty 

 •cubic centimetres of water used are then diluted to 100 c. c. with dis- 

 tilled water, and the whole subjected to distillation in a small retort, 

 the distillates being tested for ammonia with Nessler's reagent. 



Miss Talbot " concluded, as the result of some determinations made 

 with Remsen's method, that all of the organic matter fails to be con- 

 verted into ammonia during the first distillation. She found that the 

 second and third re-distillation of the distillates uniformly give higher 

 results. She sought to overcome this difiiculty by aspirating the air 

 directly through the boiling permanganate in the retort. 

 • Dr. Abbott ''' found, as the result of his investigations, that in 

 ^' 31 estimates made upon the outside air, the air of the laboratory, air 

 from over decomposing meat infusions, and the air from over sewage, 

 we have failed to obtain evidence of the existence of more than a trace 

 of gaseous, nitrogenous, organic matters, other than ammonia ; the 

 amounts being constantly so small as to fall far below the permissible 

 limits of experimental error." 



