226 now cKors feed, 



ulmic acid. By boiling it with caustic soda or potash-lye. 

 it is converted without change of composition into ulmic 

 acid. 



On gently heating sugar with dilute hydrochloric acid, 

 :i brown substance is produced, which appears to be iden- 

 tical witli the ulmic acid obtained from peat. 



Humic Acid and Hiimiii. — By treating black humus 

 with carbonate of soda as above described, it is separated 

 into hum^k' acid and humhr^', which closely resemble ulmic 

 acid and ulmin in all their properties — possess, however, a 

 black color, and, as it appears, a somewhat different com- 

 ])Osition. 



Humic acid and humin may be obtained also by the 

 action of hot and strong hydiochloric acid, of sulphuric 

 acid, and of alicalies, upon sugar and the other members 

 of the cellulose group. 



(ompositiou of Ulmin, Ulmic Acid, Humin, and Humic 

 Acid. — The results of tlie analyses of these bodies, as ob- 

 tained by different experimenters and from different 

 sources, are not in all cases accordant. Either several dis- 

 tinct substances have been confounded under each of the 

 above names, or the true xdmin and luimin, and ulmic and 

 liumic acids, are liable to occur mixed with other matters, 

 from which they cannot be or have' not been perfectly 

 separated. 



Mulder {Chemie der Ackerhrume^ 1, p. 322), who has 

 chiefly investigated these substances, believes there is a 

 group of bodies having in general the characters of ulmin 

 and ulmic acid, whose composition differs only by the ele^ 

 ments of water,f and is exhibited by the general formula 



C,„ H,« O,, + nH^O, 

 in which nll.,0 siucnifies one, two, three, or more of water 



• See note ou page 225. 



t lu a way analogous to what is known of the sugars. (li. C. G., p. 



