AMBREIC, CASTORTC, AND BOMBYCIC ACIDS. 27 

 SECTION XXI. OF AMBREIC ACID. 



Described in the Chemistry of Inorganic Bodies, (ii. 141.) 



SECTION XXII. OF CASTORIC ACID. 



This acid was obtained by Brandes* from casforin, a substance 

 extracted from castor, which is secreted in two bags in the ingui- 

 nal regions of the beaver. 



When castorin is treated with nitric acid till it is completely 

 decomposed, and the residual liquid concentrated, small yellow 

 prisms and grains are deposited, which constitute castoric acid. 



It reddens litmus-paper ; it is soluble in water, and the solu- 

 tion is yellow ; it forms with ammonia a supersalt, which crys- 

 tallizes in small grains. This salt, when neutral, does not pre- 

 cipitate the salts, having the alkaline earths for bases. But it 

 throws down the salts of protoxide of iron white ; the salts of cop- 

 per light-green ; the salts of lead and the nitrate of silver white ; 

 and these last precipitates do not alter their colour by exposure 

 to the air. 



SECTION XXIII. OF BOMBYCIC ACID. 



It was observed by Chaussier in 1783, that silk-worms have 

 the property of reddening litmus-paper. Hence he inferred that 

 they contained a peculiar acid.f It appears, from Chaussier's 

 statement, thatBoissier de Sauvage had already noticed this acid ; 

 but neither of them gave any account of its properties, or seem 

 to have attempted to procure it in a separate state. 



In 1836, M. Mulder mixed together 100 grammes of raw yel- 

 low silk and 50 grammes of sulphuric acid previously diluted 

 with 5 litres of water in a retort, and distilled cautiously that the 

 heat might not be sufficiently high to injure the silk.J The li- 

 quid which came over was acid, and had a strong and peculiar 

 smell. To free it from any sulphuric acid which it might have 

 contained, an excess of bary tes water was added, and the sulphate 

 of bary tes being separated, the uncombined barytes which it might 

 still cpntain was thrown down by a current of carbonic acid gas. 



The liquid was then evaporated to dryness, and a saline crust 

 was obtained, which was bombycic acid. When a little sulphu- 



* Br. Arch. xvi. 281. 



t Nouv. Mem. de Dijon, 1783, p. 70 ; or Ci ell's Annalen, 178*, i. 576. 



J Poggendorfs Annalen, xxxvii. 611. 



