PRODUCTS OF PUTREFACTION. , 89 



which is capable of entering into combination with 

 carbonic acid and of forming a volatile salt. Am- 

 monia in its gaseous form, as well as all its volatile 

 compounds, is of extreme solubility in water.* Am- 

 monia, therefore, cannot remain long in the atmo- 

 sphere, as every shower of rain must condense it, and 

 convey it to the surface of the earth. Hence also, 

 rain-water must at all times contain ammonia, though 

 not always in equal quantity. It must be greater in 

 summer than in spring or in winter, because the in- 

 tervals of time between the showers are in summer 

 greater ; and when several wet days occur, the rain 

 of the first must contain more of it than that of the 

 second. The rain of a thunder-storm, after a long- 

 protracted drought, ought for this reason to contain 

 the greatest quantity which is conveyed to the earth 

 at one time. 



But we have formerly stated, that all the analyses 

 of atmospheric air hitherto made have failed to de- 

 monstrate the presence of ammonia, although, ac- 

 cording to our view, it can never be absent. Is it 

 possible that it could have escaped our most delicate 

 and most exact apparatus ? The quantity of nitro- 

 gen contained in a cubic foot of air is certainly ex- 

 tremely small, but, notwithstanding this, the sum of 

 the quantities of nitrogen from thousands and mil- 

 lions of dead animals is more than sufficient to sup- 

 ply all those living at one time with this element. 



From the tension of aqueous vapor at 15^ C. (59^ 

 F.) = 6,98 lines (Paris measure), and from its known 

 specific gravity at 0^ C. (32° F.), it follows that 

 when the temperature of the air is 59° F. and the 

 height of the barometer 28'', 1 cubic metre or 35*3 

 cubic feet of aqueous vapor are contained in 487 

 cubic metres, or 17,198 cubic feet of air; 35-3 cubic 

 feet of aqueous vapor weigh about 1.65 lb. Conse- 

 quently, if we suppose that the air saturated with 

 moisture at 59° F. allows all the water which it con- 



* According to Dr. Thomson, water absorbs 780 times its bulk of 

 ammonia. 



8* 



