94 



AGRICULTURAL CHEMISTRY. 



tions, whatever may be the cause which 

 produces the decompositions. All organic 

 compounds containing nitrogen, evolve the 

 whole of that element in the form of ammo- 

 nia when acted on by alkalies. Acids, and 

 increase of temperature, produce the same 

 effect. It is only when there is a defi- 

 ciency of water or its elements, that cyno- 

 gen or other azotised compounds are pro- 

 duced. 



From these facts it may be concluded, 

 that ammonia is the most stable compound 

 of nitrogen ; and that hydrogen and nitro- 

 gen possess a degree of affinity for each 

 other surpassing the attraction of the latter 

 body for any other element. 



Already in considering the transforma- 

 tions of substances destitute of nitrogen, we 

 have recognised the great affinity of carbon 

 for oxygen as a powerful cause for effecting 

 the disunion of the elements of a complex 

 organic atom in a definite manner. But car- 

 bon is also invariably contained in azotised 

 organic compounds, while the great affinity 

 of nitrogen for hydrogen furnishes a new 

 and powerful cause, facilitating the transpo- 

 sition of their component parts. Thus, in 

 the bodies which do not contain nitrogen we 

 have one element, and in those in which 

 that substance is present, two elements, 

 which mutually share the elements of water. 

 Hence there are two opposite affinities at 

 play, which mutually strengthen each other's 

 actions. 



Now we know, that the most powerful 

 attractions may be overcome by the influ- 

 ence of two affinities. Thus, a decomposi- 

 tion of alumina may be effected with the 

 greatest facility, when the affinity of char- 

 coal for oxygen, and of chlorine for alumi- 

 nium, are both put in action, although nei- 

 ther of these alone has any influence upon 

 it. There is in the nature and constitution 

 of the compounds of nitrogen a kind of ten- 

 sion of their component parts, and a strong 

 disposition to yield to transformations, which 

 effect spontaneously the transposition of 

 their atoms on the instant that water or 

 its elements are brought in contact with 

 them. 



The characters of the hydrated cyanic 

 acid, one of the simplest of all the com- 

 pounds of nitrogen, are perhaps the best 

 adapted to convey a distinct idea of the 

 manner in which the atoms are disposed of 

 in transformations. This acid contains ni- 

 trogen, hydrogen, and oxygen, in such pro- 

 portions, that the addition of a certain quan- 

 tity of the elements of water is exactly suffi- 

 cient to cause the oxygen contained in the 

 water and acid to unite with the carbon and 

 form carbonic acid, and the hydrogen of the 

 water to combine with the nitrogen and 

 form ammonia. The most favourable con- 

 ditions for a complete transformation are, 

 therefore, associated in these bodies, and it 

 is well known, that the disunion takes place 

 on the instant in which the cyanic acid and 

 water are brought into contact, the mixture 



being converted into carbonic acid and am 

 monia, with brisk effervescence. 



This decomposition may be considered as 

 the type of the transformations of all azo- 

 tised compounds; it is putrefaction in its 

 simplest and most perfect form, because the 

 new products, the carbonic acid and ammo- 

 nia are incapable of further transformations. 



Putrefaction assumes a totally different 

 and much more complicated form, when the 

 products, which are first formed undergo a 

 further change. In these cases the proress 

 consists of several stages, of which it is im- 

 possible to determine when one ceases and 

 the other begins. 



The transformations of cyanogen, a bodv 

 composed of carbon and nitrogen, and the 

 simplest of all the compounds of nitrogen, 

 will convey a clear idea of the great variety 

 of products which are produced in such a 

 case : it is the only example of the putrefac- 

 tion of an azotised body which has been at 

 all accurately studied. 



A solution of cyanogen in water becomes 

 turbid after a short time, and deposits a 

 black, or brownish black matter, which is a 

 combination of ammonia with another body, 

 produced by the simple union of cyanogen 

 with water. This substance is insoluble in 

 water, and is thus enabled to resist further 

 change. 



A second transformation is effected Vy the 

 cyanogen being snared between the elements 

 of the water, in consequence of which 

 cyanic acid is formed by a certain quantity 

 of the cyanogen combining with the oxygen 

 of the water, while hydrocyanic acid is also 

 formed by another portion of the cyanogen 

 uniting with the hydrogen which was libe- 

 rated. 



Cyanogen experiences a third transforma- 

 tion, by which a complete disunion of its 

 elements takes place, these being divided be- 

 tween the constituents of the water. Oxa- 

 lic acid is the one product of this disunion, 

 and ammonia the other. 



Cyanic acid, the formation of which has 

 been mentioned above, cannot exist in con- 

 tact with water, being decomposed immedi- 

 ately into carbonic acid and ammonia. The 

 cyanic acid, however, newly formed in the 

 decomposition of cyanogen, escapes this de- 

 composition by entering into combination 

 with the free ammonia, by which urea is 

 produced. 



The hydrocyanic acid is also decomposed 

 into a brown matter which contains hydro 

 gen and cyanogen, the latter in greater pro 

 portion than it does in the gaseous state. 

 Oxalic acid, urea, and carbonic acid, are also 

 formed by its decomposition, and formic acid 

 and ammonia are produced by the decompo- 

 sition of its radical. 



Thus, a substance into the composition 



of which only two elements (carbon and 



I nitrogen) enter, yields ei^ht totally different 



: products. Several of these products a-e 



; formed by the transformation of the original 



body, its elements being shared between the 



