ORGANIC CHEMISTRY. 77 



as decidedly a vegetable production, as it is found in the kernel of 

 the peach, plum, and bitter ahnond, in the leaf of the laurel, &c., 

 but if animal fibre, mixed with potash or its carbonate, be projected 

 into a strongly-healed crucible, the mass becomes pasty, and affords, 

 by solution and crystallization, a salt of potash containing this acid. 



Urea J the last product we shall mention, can be produced by 

 combining prussic acid, or cyanogen, with ammonia. It is probable 

 that both the cyanogen and the ammonia are decomposed, and that 

 their elements re-uniting, and combining with the elements of 

 water, under a different system of molecular arrangement, give rise 

 to this remarkable result ; for ammonia is not evolved on the addi- 

 tion of agents, such as potash, whose affinities are more powerful 

 than those of ammonia. 



Can we contemplate, without astonishment, the facility with 

 which organic matter is changed into a variety of products, possess- 

 ing properties the most dissimilar ? What can be more different than 

 sugar and oxalic acid, gum and alcohol, from the insipid, insoluble 

 woody fibre from which they were formed, or sugar, prussic acid, 

 and ammonia, from animal fibrin ? Yet when we examine the na- 

 ture of the change which has taken place — when we reflect on the 

 very small differences which the ultimate analysis of the various 

 substances indicates — our astonishment is, if possible, heightened. 

 Thus, woody fibre differs from gum in the proportion of its carbon, 

 while gum and sugar absolutely consist of the same elements, 

 united in the same proportion. Other instances, of a similar descrip- 

 tion, are not wanting — " Acetic acid has a strong and aromatic 

 smell, succinic acid has no smell whatever. Acetic acid is so solu- 

 ble in water that it is difficult to obtain it in crystals, and it cannot 

 be procured in a separate state, free from water ; but succinic acid 

 is not only easily obtained free from water, but it is not even very 

 soluble in that liquid. The nature of the salts formed by these 

 acids is quite different ; the action of heat upon each is, also, quite dif- 

 ferent ; the specific gravity of each differs ; in short, all their proper- 

 ties exhibit a striking contrast."* Yet these acids are composed of 

 the same number of atoms of the same elements, and their atomic 

 number is also, of course, the same. That tremendously explosive 

 acid, the fulminic, is identical, so far as being constituted of the 

 same elements, combined in the same proportions, can render it, 

 with the cyanic acid ; yet they do not even resemble each other in 

 any one particular, excepting that their neutralizing power is the 

 same, or, in other w^ords, that their atomic number is the same. 



• History of Chemistry. 



