10 TKAXSACTIONS AND PROCEEDINGS OF THE [Sess. Lxi. 



the decomposition of nitrogenous compounds in a number 

 of ways. "When, in the ordinary course of nature, living 

 things, be they animal or vegetable, fall into decay, the 

 nitrogenous compounds they contain do not all escape into 

 the air as ammonia, as was at one time believed. Liebig, 

 in his famous book on " Organic Chemistry in its Applica- 

 tion to Agriculture and Physiology," published in the 

 middle of this century, taught that from carbonic acid 

 gas, water, and ammonia, came the food of the world, and 

 back to carbonic acid, water, and anmionia it all returned, 

 either directly in its decay, or indirectly in the life and 

 death of the animals whose frames it temporarily served to 

 support. It was a "beautiful generalisation, this cycle of 

 change through which all organic life was held to pass ; 

 but careful investigation of the products of organic decay 

 has shown that much of the albumen, and other nitro- 

 genous matter contained in living organisms, is decomposed 

 during their life, as well as at their death, into something 

 even simpler than ammonia, viz. into the element nitrogen 

 itself. 



The proportion of the albuminoid matter reduced in this 

 way may be very considerable, and may even amount to 

 one-fourth of the whole of the nitrogen of the substance if 

 conditions are favourable. Even when the nitrogenous 

 organic matter has had its nitrogen converted into the 

 inorganic form of nitrates, or nitrites, it is not safe ; for 

 apart altogether from the extreme ease with which these 

 salts are washed out of the soil and into the water-courses 

 by rain, they are, while resident in the soil, liable to be 

 reduced in the presence of much organic matter, especially 

 if cut off from a circulation of air ; and that reduction, 

 stopping short of ammonia, liberates their nitrogen in the 

 uncombined state. 



It has been observed that these instances of reduction 

 are greatly hastened, if they are not entirely brought about, 

 through the instrumentality of micro-organisms in the 

 soil, or in any place where organic matter is accumulated. 

 ]5ut also in the presence of air there are decompositions 

 taking place in decaying organic matter, whereby oxidised 

 and unoxidised ])roducts re-act u])on each other' and liberate 

 the whole of th(;ir nitrogen as free nitrogen "as. 



