﻿24 



METHODS FOE THE DETERMINATION OF 



The marked variation in the total amounts of organic matter found 

 in simultaneous determinations with these three methods shows that 

 no reliance can be placed on the results obtained by at least two of 

 these methods. The nearly uniformly low results obtained with 

 method Ill-b indicate that this method is the preferable one of the 

 three entering into this experiment. 



TABLE XIII. 



No. of 

 experi- 



Date, 



1896. 



Source of 

 the air. 



Amount of 

 air 



Time 

 taken in 



With or 

 without 



Method. 



Mgs. of consumed 

 for 1 cbm. of air. 



ment. 



aspirated. 



aspirating. 



dust-filter. 





1 



4-III 



Room 



52.0 L. 



6f hrs. 



With 



Ill-b 



3.8658 mgs. 



2 



4-III 





72.7 " 



Qi. " 



Without 



Ill-b 



7.2145 





3 



4-I1I 





13.1 " 



ei - 



With 



I-b 



8.2900 





4 



4-III 





15.4 " 



6| " 



Without 



I-b 



6.3661 





5 



5-III 





158.0 " 



7 - 



With 



Ill-b 



1.7684 



i 



6 



5-111 





113.2 " 



7 " 



Without 



Ill-b 



3.6374 





7 



5-III 





13.75 " 



7 " 



With 



I-b 



35.6506 





8 



5-III 





13.3 - 



7 " 



Without 



I-b 



20.6398 " 



The results obtained with method Ill-b show a constant influence 

 from the dust-filter attached, but those obtained with method I-b fail 

 to show such an influence ; in fact, the results are invariably higher, 

 from some unexplained cause, in the determinations with the dust-filter 

 than in those in which it was not used. It seems, therefore, that 

 method I-b is not reliable, even with the utmost care possible. 



TABLE XIV. 



No. of 



Date, 

 1896. 



Amount 



of air 

 aspirated. 



Time 

 taken 

 in aspi- 

 rating. 



Source 



of the 



air. 



With or with- 

 out dust- 

 filter. 



Method. 



Mgs. of NHs in 1 cbm. of air. 



ment. 



Free NH3 



Alb. NH, 



1 



6-1 



434.5 L. 



23Jh. 



Room 



With 



Ill-a 



0.0092 mgs. 



0.0103 mgs. 



2 



6-1 



1051.9 " 



23i" 



(( 



Without 





0.0294 " 



0.0175 " 



3 



7-1 



437.0 " 



25 " 





With 





0.0137 '' 



0.0034 " 



4 



7-1 



1033.5 " 



25" 





Without 





0.0387 " 



0.0062 " 



5 



9-1 



838.0 " 



25 " 





With 





0.0095 " 



0.0053 " 



6 



29-1 



1158.6 " 



25 " 





Without 





0.0232 " 



0.0081 " 



7 



25-11 



698.5 " 



24^- " 





With 





0.0114 " 



0.0078 " 



8 



25-11 



766.9 " 



24| " 





Without 





0.0182 " 



0.0071 " 



9 



26-11 



686.5 - 



241" 





With 





0.0182 " 



0.0043 " 



10 



26-11 



758.7 " 



24i" 





Without 





0.0237 '• 



0.0158 " 



11 



27-11 



727.5 " 



24" 





With 





0.0343 " 



0.0013 " 



12 



27-11 



819.8 " 



24" 





Without 





0.0536 " 



0.0030 " 



13 



28-11 



480.0 " 



25|" 





With 





0.0156 " 



0.0041 " 



14 



28-11 



873.9 " 



25| " " 



Without 





0.0583 " 



0.0005 " 



This table shows the results obtained in a series of simultaneous 

 determinations with Method III- a, with and without the use of a dust- 



