432 [Senate 



5. Coal of humus;* 



6. Extract of humus. 



Crenic acid exists most abundantly in the subsoil from which it is 

 in part separated by water or alcohol, or still better, by a weak solu- 

 tion of carbonate of ammonia, which decomposes the crenates of lime, 

 alumina and iron, and takes up their crenic acid. 



Crenic acid, as I ascertained, exists in soils and peat from various 

 localities. It is universally present in the soils of every quarter of the 

 globe. Crenic acid is composed, by weight, of C. 14.24, H. 7.69, 

 N. 7.50, Ox. 44.57, or C. 7, H. 16, O. 6, N. 1, atomically. Ap- 

 ocrenic acid is distinguished by its forming dark brown salts with bina- 

 cetate of copper. It is most abundant in the black mould of the sur- 

 face, and especially in long cultivated soils. It may be separated from 

 its copper salt by the action of sulph-hydric acid gas. 



It is a very highly nitrogenized substance, and is composed of — 



Carbon, 62.57 or 14. Atoms. 



Hvdrogen, 4.80 " 14. " 



Nitrogen, 15.00 " 3. " 



Oxygen, 17.63" 3. " {Hermann.) 



This acid is formed by long exposure of crenate of ammonia to 

 atmospheric influence. It is formed by exposure of peat to the 

 action of ammoniacal manures in presence of atmospheric air. Hu- 

 mic, glucic and apoglucic acids are readily converted into it by cata- 

 lytic action. 



The carbonate of ammonia, which is washed out from the air by 

 rain, is fixed by mould in the state of soluble apocrenate of ammonia, 

 which is a much better manure than the sulphate. 



HuMic Acid. — After separating the apocrenic and crenic acids from 

 the solution in carbonate of ammonia, we free the solution remaining 

 from copper, by passing sulph-hydric acid gas through it, so long as it 

 gives a precipitate ; then filter and obtain a brownish yellow solution, 

 which contains humic acid and extract of humus. Boil the solution un- 

 til freed from sulph-hydric acid, or evaporate to near dryness, and re- 

 disolve in water. Add now a solution of sub-acetate of lead, and a 

 greyish precipitate of the humate of lead is thrown down. Collect 

 this on a filter, wash it and then decompose it by sulph-hydric acid gas; 

 filter, evaporate in vacuo to dryness, and obtain humic acid. 



It is composed of C. 30, H. 30, 0. 15. — Sprengel Malaguti ; — or 

 according to Mulder, of C. 40, H. 26, O. 12. 



It forms soluble salts with lime, and with all the alkalies. It is not 

 precipitated by salts of copper. It forms with persalts of iron humate 

 of the peroxide, which is of a yellow color. It is this salt, chiefly, 

 which gives the yellow color to subsoils. 



After clearing from lead, the solution from which the humate of lead 

 had been thrown down, we evaporate to dryness in vacuo, and obtain 

 a brown extract, which is called extract of humus. This is a highly 

 nitrogenized compound, which, when treated %vith proto-nitrate of 

 mercury and nitrate of silver, yields two different salts, that have not 

 yet been analyzed or described. 



* Probably altered humin or humic acids, for it is not obtained when the operation 

 of evaporation is conducted in vacuo without heat. 



