Recent Publications on Manures. 91 



ulmic acid absorbed by the roots can be assimilated, we may 

 conclude it will be the same with all. 



In the appendix he resumes the subject of ulmic acid, and 

 says it is an important fact, resulting from the constitution of 

 organic matter, that all the most abundant proximate principles 

 of the vegetable and animal kingdoms cannot undergo decay 

 without producing ulmic acid. During the formation of car- 

 bonic acid by the decomposition of any substance, as many 

 atoms of hydrogen, he says, are evolved in the form of water as 

 there are atoms of oxygen required to produce the carbonic 

 acid ; and this change cannot take place in any organic com- 

 pound without the production of ulmic acid. In sugar, for 

 instance, he says, composed of ] 2 atoms each of carbon, hy- 

 drogen, and oxygen, or C. 12, H. 12, O. 12, when 4 atoms 

 of carbonic acid are formed, the result will be (4 C, O. 2) + 

 (8 H., O.) + (C. 8, H. 4, O. 4); or 4 atoms of carbonic acid, 

 8 of water, and 4 of ulmic acid. In the same way with starch 

 and lignin : for every atom of carbon, 2 of hydrogen and 

 oxygen being evolved, the proportion will ultimately arrive at 

 2 of carbon for every 1 of hydrogen and oxygen, which is the 

 proportion of ulmic acid. In the same way with animal albu- 

 men, composed of C. 15, H. 14, O. 6, N. 2 ; it is resolved, 

 by the decomposition of 2 atoms of water, into (C, O. 2) + (2 

 N., H. 3) + (2 C, H. 2) + (C. 12, H. 6, O. 6); or 1 atom 

 of carbonic acid, 2 of ammonia, 2 of carburetted hydrogen, and 

 6 of ulmic acid. Ulmic acid is, on this account, he says, con- 

 stantly produced by the slow combustion or decomposition of 

 all organic matter; and ulmate of ammonia, he concludes, is 

 the true food of plants, as obtained from the soil : it contains, 

 he says, y 1 ^ part of nitrogen, and in no plant does the nitrogen 

 amount to so great a proportion to the carbon ; and it appears 

 probable, he thinks, that no more carbon is obtained from the 

 soil than is obtained in this way ; the rest of the carbon is got 

 from the air. Fallow plants thus, he says, regenerate the soil ; 

 as they require little nitrogen, and draw their carbon mostly 

 from the air. 



I have extracted thus largely from the above-noticed va- 

 luable essay on the subject of humus; as the question is much 

 controverted at present, and it was impossible to do justice to 

 the author's views in a more concentrated form. The action of 

 ammonia, and carbonate of ammonia, on the humus in the soil, 

 seems incontrovertibly established, and is very valuable and 

 interesting. The chemical action of the soil on the ulmate of 

 ammonia was not suspected ; and if future experiments prove the 

 truth of this conjecture, it will be found greatly to modify pre- 

 viously entertained opinions. In the experiment of pouring die 

 ulmate of ammonia on the soil in the flower-pot, might not the 



