398 DERIVATIVES OF THE PROTEIN-COMPOUNDS. 



tant but easily injured organs ; they give uniformity to the move- 

 ments of the body through their elasticity, and protect it from the 

 injurious effects of severe concussions ; from being bad conductors 

 of heat, they guard the body against rapid changes of temperature ; 

 and sometimes, as in the cornea, they are useful as refracting media, 

 in consequence of their transparency. 



CHONDBIN. 



Chemical Relations. 



Properties. Chondrin or cartilage-gelatin, when dry, appears 

 as a transparent, horny, glistening mass, which is generally more 

 colourless than glutin ; it is not rendered electric by friction ; its 

 behaviour towards indifferent solvents, towards heat, corrosive 

 sublimate, tannic acid, and chlorine, is precisely the same as that 

 of glutin ; but its relations to acids and most metallic salts are quite 

 different. It was shown by Miiller* that acetic acid throws down a 

 considerable precipitate from a solution of chondrin, and that this pre- 

 cipitate does not dissolve even in concentrated acetic acid. Simonf 

 and VogelJ have subsequently proved that most acids throw down 

 a precipitate from a solution of chondrin, but that this precipitate 

 easily escapes notice in consequence of the facility with which it 

 dissolves in a slight excess of the acid. Alum, the sulphates of the 

 protoxide and peroxide of iron, sulphate of copper, neutral and basic 

 acetate of lead, and the nitrates of silver, and of suboxide of mercury 

 throw down copious precipitates. The precipitates thrown down 

 by the salts of alumina occur in white, compact flocks, which on 

 drying, cake very much together ; they are insoluble in water, but 

 dissolve in an excess of the earthy salt, as well as in solutions of 

 chloride of sodium and of alkaline acetates. The precipitate thrown 

 down by sulphate of peroxide of iron is not soluble in an excess of 

 that salt, but dissolves on boiling. In its relations towards ordi- 

 nary atmospheric influences as well as towards alcohol, creosote, 

 chlorine, bromine, iodine, and ferrocyanide of potassium, chondrin 

 perfectly resembles glutin. Its combinations with other bodies and 

 its products of decomposition have not yet been accurately studied. 



Composition. Mulder was the first who made an elementary 



* Pogg. Ann. Bd. 38, S. 295. 



t Medicin. Chemie, Bd. 1,8. 108. 



J Jonrn. f. pr. Ch. Bd. 21, S. 426. 



Natuur en Schcik. Arch. 1837, p. 450, and 1838, p. 160. 



