86 SOURCE AND ASSIMILATION OF NITROGEN. 



ammonia, which consists of this element and hydro- 

 gen. Now, the nitrogen of the air cannot be made 

 to enter into combination with any element except 

 oxygen, even by the employment of the most power- 

 ful chemical means. We have not the slightest 

 reason for believing that the nitrogen of the atmo- 

 sphere takes part in the processes of assimilation of 

 plants and animals; on the contrary, we know that 

 many plants emit the nitrogen which is absorbed by 

 their roots, either in the gaseous form, or in solution 

 in water. But there are on the other hand numerous 

 facts, showing, that the formation in plants of sub- 

 stances containing nitrogen, such as gluten, takes 

 place in proportion to the quantity of this element 

 which is conveyed to their roots in the state of 

 ammonia,* derived from the putrefaction of animal 

 matter. 



Ammonia, too, is capable of undergoing such a 

 multitude of transformations, when in contact with 

 other bodies, that in this respect it is not inferior to 

 water, which possesses the same property in an 

 eminent degree. It possesses properties which we 

 do not find in any other compound of nitrogen : 

 when pure, it is extremely soluble in water; it forms 

 soluble compounds with all the acids ; and when in 

 contact w^ith certain other substances, it completely 

 resigns its character as an alkali, and is capable of 

 assuming the most various and opposite forms. 

 Formate of ammonia f changes, under the influence 

 of a high temperature, into hydrocyanic acid and 

 water, without the separation of any of its elements. 



* Ammonia is a compound gas, consisting of one volume of nitrogen 

 and three volumes of hydrogen. It is produced during the decompo- 

 sition of many animal substances. It is given off when sal-ammoniac 

 and lime are rubbed together. It was formerly called volatile alkali. 



t Formic acid (p. 70. n.) is also obtained from sugar and many other 

 vegetable substances ; a pound of sugar yields a quantity capable of 

 saturating five or six ounces of carbonate of lime. A process for 

 obtaining it has been given by Emmet in the American Journal^ Vol. 

 XXXII. p. 140. See details in Webster's Manual of Chemistry, 3d 

 edition, p. 374. 



Its composition is carbon 2, water 3. With ammonia and other 

 bases it yields the salts called formates. 



