500 



.Mi;. .1. II. I.WVF.s. DR. GILBERT, AM) DR. PUGH <>\ 



tive result. The mass was then re-exhausted with water, and the extract rnbmitfa 

 precisely the same process as before, when the presence of nitric acid was made manii 



In the following Table are given the numerical results of tli«- tax experiments: — 



Table VIT. — Showing the Numerical results of experiments on tin- Decomposition of 

 Nitrogenous organic matter, made in 1857. 



The last two columns of this Table, which exhibit respectively the actual amount of 

 Nitrogen not recoverable by the soda-lime process in the substance after decomposition, 

 and the percentage proportion of this loss upon the Nitrogen submitted to experiment, 

 are the most important to consider for our present purpose. 



With one exception (the gain of Nitrogen in which is quite within the range of the 

 error of analysis), all the experiments point to the fact, that a part of the Nitrogen of 

 decomposing organic matter passes into a state in which it cannot be estimated by the 

 soda-lime process. Neither did it exist as nitric acid. There appears, therefore, to be 

 an evolution of free Nitrogen. 



It is not a little remarkable, that although so large a proportion of the total Nitrogen 

 present is lost, doubtless passing off as free Nitrogen, yet scarcely a trace of ammonia 

 was given off from the mass ; for the oxalic acid in the bulb-apparatus C was. in each 

 case, separately rendered alkaline with caustic potash and distilled, the distillate being 

 collected and examined quantitatively for ammonia, when, in only one case — that of the 

 Bean-meal and Pumice — was there any ammonia indicated, and then only equal in 

 amount to 0-0002 gramme Nitrogen. This was the case, notwithstanding that the 

 Nitrogen in the mixtures amounted to from 0'03 to 0-08 per cent, of their entire 

 quantity. 



The questions here arise : — to what extent had the decomposition of the organic sub- 

 stance proceeded ] what shall we accept as the measure of the amount of decomposition ? 

 what are the intermediate stages through which the substance has passed ? what is the 

 character of the organic compounds remaining in the mass I what is the nature of those 

 that have been evolved] and what part does water play in the matter ? 



The subject of the character of the gradual changes which take place during the 



