94 HISTORY OF GEINE. 



hydrogen, O oxygen, Am. ammonia, a compound of 3 hydro- 

 gen and 1 nitrogen; and Aq. stands for water (aqua), a 

 compound of one of hydrogen and 1 of oxygen ; 2 aq. is 2 

 water. 



TABLE OF COMPOSITION OF ULMIN, ETC. 



It is thus seen that ulmic and humic acids differ from 

 ulmin and humin, by containing, the first, two, and the 

 second, three, atoms of the elements of water less than the 

 neutral bodies from which they are formed. The ulmic and 

 humic acids above, are supposed to be perfectly dry. Each 

 may combine with a definite proportion of water, forming 

 hydrated acids. In this case they contain the same absolute 

 and relative number of the same elements as do ulmin and 

 humin. They are thus said to be isomeric with them. The 

 composition of the hydrated acids is — 



Ulmic, C*' H^* O^' -f 2 aqua or 2 hydrogen and 2 oxygen. 

 Humic, 0° H^^ O'' + 3 aqua or 3 « "3 " 



These acids combine with bases. If these acids are dis- 

 solved by ammonia, and precipitated by an acid, they fall 

 combined with ammonia. Ulmate of ammonia, precipitated 

 by metallic salts, forms double salts of ammonia and a 

 metallic oxide. The composition of these salts of ammonia 



