28 ANIMAL ACIDS CONTAINING AZOTE. 



ric acid was mixed with this crust, a sharp and penetrating smell 

 was perceived, and a white vapour exhaled, which acted as an 

 acid. From this experiment it follows, that silk contains an acid 

 which is separated from it by sulphuric acid ; that this acid is vo- 

 latile, has a strong smell, and forms a soluble salt with barytes. 



Bombycic acid is not found in the fibres of silk, but in its ge- 

 latin and albumen. It may be obtained by boiling the raw silk 

 in water, and evaporating the liquid. 



When mixed with a great deal of water, it has a peculiarly 

 strong fatty smell, is very volatile ; has a sharp taste, and reacts 

 weakly as an acid. When exposed to the light, it is decompos- 

 ed ; the peculiar smell vanishes, and a crop of mucors make their 

 appearance. 



It forms soluble salts with lime, barytes, potash, soda, and am- 

 monia, and is separated from these bases by the strong acids, as 

 becomes evident by the smell. Its solution in water is not pre- 

 cipitated by salts of iron, mercury, copper, and silver, showing 

 that its combinations with the bases of these salts are soluble. 



Concentrated acids mixed with dilute aqueous solutions of 

 bombycic acid do not act upon it, if we except muriatic acid, 

 which occasions a smell similar to that of iodine. 



It is obvious, from the characters of this acid, thus determined 

 by Mulder, that it is neither cyanic acid, as Liebig conjectured, 

 nor benzole acid, as was the opinion of Proust. 



CHAPTER II. 



ANIMAL ACIDS CONTAINING AZOTE. 



THESE acids are all, or at least the greater number of them, 

 feeble. They amount at present to about eighteen species ; but 

 they will probably be greatly augmented as the examination of 

 animal substances proceeds. 



SECTION I. OF CYANOGEN AND ITS COMPOUNDS. 



These have been treated of at great length in the Chemistry 

 of Inorganic Bodies, (Vol. ii. p. 208,) and- in the Chemistry of 

 Vegetable Bodies, (p. 207.) But the compounds of this very pro- 

 lific substance are so numerous, that it may not be improper to 

 give a list of the principal of them in this place. 



