490 Miscellaneous Intelligence, 



proportions, but now finds it to be in perfect obedience to it. Its 

 composition is as follows by experiment and theory : — 



Theory, 



/ V 



Carbon 35.043 36.081 15 atoms. . 114.65 



Azote 16.167. . . . 16.714 3 53.11 



Oxygen . . ..48.790. . . . 47.205 . . . , 15 , 150.00 



100,000 100.000 • S17.76 



Carhazofate of Baryta. — 100 parts lose, at 212° Fah. 125 parts 



of water; 100 parts of the anhydrous salt contain 75.72 acid, and 



24.28 baryta. 



. Proto Carbazotate of Mercury consists of 53.79 acid, and 46.21 



protoxide of mercury per cent. 



Carbazotate of Lead may be formed by decomposing a salt of lead 



by carbazotate of potash or soda ; it is a yellow powder, but slightly 



soluble, and detonating by heat. — Annates de Chimiej xxxvii. 286. 



28. On ChevreuVs Acid of Indigo, by Dr. Buff. — Dr. BufFhas been 

 engaged in an examination of the action of nitric acid on indigo, 

 principally with a view to ascertain the relation of the substances 

 which Chevreul formerly described as produced by this action to 

 the carbazotic acid of Dr. Liebeg. He finds Chevreul's acid to be 

 quite distinct from the latter. To obtain it, nitric acid of 32° 

 (s.g. 1.285) was diluted with rather more than its weight of water, 

 heated in a retort, and small portions of indigo in fine powder 

 added as long as sensible effervescence was produced ; a little water 

 was added, from time to time, to prevent the formation of carba- 

 zotic acid. The yellow liquid was separated, whilst hot, from the 

 resinous matter, and by cooling deposited crystals of the acid of 

 indigo. This was boiled with oxide of lead, filtered, and the salt 

 present decomposed by sulphuric acid whilst hot ; on cooling, the 

 liquor deposited the acid of indigo in yellowish white crystals j 

 these were separated, dissolved in hot water, neutralized by car- 

 bonate of baryta, the solution concentrated, and allowed to cool ; 

 yellow aciciilar crystals of a baryta salt were obtained, which 

 being washed with cold water, dissolved in hot water, and decom- 

 posed by acids, gave acicular crystals of the acid of indigo, white 

 as snow ; they were collected, and washed upon a filter, and 

 shrunk into a small space when dry, losing almost entirely their 

 crystalline aspect. 



This acid is white, having the lustre of silk ; it has a weak acid, 

 bitter taste, reddens litmus, dissolves in any quantity in boiling 

 water or alcohol forming colourless solutions, but requires 1000 

 parts of cold water for its solution. It is volatile, and being 

 heated in a tube, fuzes and sublimes without decomposition. 

 When the fused acid is cooled, it crystallizes in six-sided plates. 

 In the air it burns with a bright flame, evolving much smoke 

 Nitric acid changes it into carbazotic acid. Neither chlorine gas, 

 nor solution of chlorine, has any effect upon it. It gives a blood- 

 red colour to solutions of the per-salts of iron. 



