HISTORY OF GKINE. 87 



The properties and relations of ulmin and of ulmic acid, 

 now engaged tlie attention of many expert chemists. It was 

 found to be the product of a great many vegetable decompo- 

 sitions by various agents, by alkali, by acids, earths, oxides, 

 by fire, by water. All these hasten the process of decay. 

 As a general law, it may be stated that all substances oxi- 

 dating, and gently acting on organic matter, produce ulmin. 

 Hence, it was found in a vast variety of substances, and 

 even cast-iron was found to contain about 2 per cent, of a 

 compound so analogous to ulmin, that it is so called. But, 

 above all, it was found to be the great product of spontane- 

 ous decay of plants, and hence existed abundantly in peat 

 and soil. Sprengel, directing his attention particularly to 

 its existence in soil before that form of it was universally 

 allowed to be identical with ulmin and ulmic acid, bestowed 

 on it the name of humic acid, from the Latin, humus, or 

 mould. Sprengel investigated minutely the various salts of 

 this substance, and first endeavored to determine its chemi- 

 cal constituents. 



Boullay soon followed in the same path of investigation, 

 and with almost similar results. There were marked differ- 

 ences between all the forms yet observed, that is, between 

 elm gum of Palermo, the product of bark, the artificial 

 ulmin of Braconnot, and that of soil. A multitude of dif- 

 ferent but analogous substances were confounded under a 

 common name, which began to be applied to the matter of 

 all vegetables, which, after having been treated with alcohol 

 and water, yielded to alkali a solution precipitable in brown 

 flocks, by an acid. Under these circumstances, Berzelius 

 objected to the term altogether, and if there is a substance 

 to which he would apply the name ulmin, it is to the mucil- 

 age of elm. As this has been the source of no small confu- 

 sion, an account of it may be here introduced. Elm bark 



