156 Maine: agricuIvTural expe;riment station. 1912. 



calculated the assay of that particular sample. That the reac- 

 tion was not complete, however, is shown by the series of 

 second readings taken after periods ranging from 16 to 72 

 hours after the first reading. The differences between the two 

 readings, while ranging from 0.2 to 2.2 cubic centimeters do 

 not correspond to the differences in time. For example, one 

 sample after standing 24 hours had increased 0.8 cubic centi- 

 meter, while another sample after standing for the same period 

 had increased 2.0 cubic centimeters. One sample standing 72 

 hours increased 2.2 cubic centimeters, while another for the 

 same period increased only 1.3 cubic centimeters. This increase 

 seemed never the same in any two cases and varied at dift'erent 

 times during the periods themselves. The rate of increase 

 depends on so many different factors, such as strength of the 

 sample, its age, the amount of water present, compounds which 

 may have been formed by decomposition, and not only the 

 temperature and pressure at the time of beginning the experi- 

 ment, but the variations while the test is being made, that it is 

 impossible to apply any corrections and the best that can be 

 done is to establish some uniform rule in regard to the time. 

 One hour was finally adopted and if the apparatus is shaken 

 several times during the interval so that the reagents are thor- 

 oughly mixed, the gas generated in sixty minutes is near enough 

 to the total amount for all practical purposes. 



TabivB 28. 



Variation in the Rate at Which Nitrogen Dioxide Gas is Liberated in 

 the Analysis of Sweet Spirit of Nitre under Different Conditions. 



§3 



Corrected 

 c 



Readings, 

 c. 



Time 



Elapsed — 



Hours. 



Difference, 

 c. c. 



Temperature, Degrees C. 



^ 



First. 



Second. 



First 

 Reading. 



Second 

 Reading. 



1 



55.9 



56.1 



16 



0.2 



21.0 



20.0 



2 



55.5 



56.4 



17 



0.9 



23.5 



. 22.0 



3 



56.8 



57.8 



22 



1.0 



20.3 



21.0 



4 



53.9 



54.7 



24 



0.8 



21.0 



22.0 



5 



48.3 



50.3 



24 



2.0 



22.2 



20.5 



6 



55.4 



56.7 



48 



1.3 



- 



20.0 



7 



49.9 



51.2 



72 



1.3 



- 



22.3 



8 



44.2 



46.4 



72 



2.2 



21.5 



21.5 



