Intelligence and Miscellaneous Articles. 315 



Carbon 72-80 or 45 atoms 1721-7 72-34 



Hydrogen . . 4-04 — 15 937 3-97 



Azote 10-80 — 15 265- .... 11-13 



Oxygen 12 36 — 3 300- 12-60 



100-00 

 According to Berzelius, deoxidized indigo, when mixed with sul- 

 phate of copper, takes from it such a quantity of oxygen, that 100 

 parts of deoxidized indigo require 4-6 of oxygen to become blue 

 indigo. 



Indigotic acid, of perfect whiteness, and consequently free from 

 carbazotic acid, which it contained when coloured, gave, 



Carbon 48-23 or 45 atoms 1721-7 4809 



Hydrogen .... 276 — 1 93-7 .... 2-61 



Azote 7-73— 3 265-0.... 7-40 



Oxygen 41-28 — 15 15000 .... 41-90 



100-00 3580-4 100-00 



M. Dumas remarks that indigotic acid is merely indigo highly 

 oxidized, containing 5 times more oxygen than blue indigo. Car- 

 bazotic acid is the substance formerly known by the name of Amer 

 de Welter. All animal matters treated with nitric acid may furnish % 

 carbazotic acid: it resists the action of the most powerful acids and 

 forms detonating salts. 



It is readily formed by treating indigotic acid with concentrated 

 nitric acid : the carbazotic acid employed by M. Dumas was pre- 

 pared from indigo, and was first converted into carbazotate of 

 potash, which was carefully purified, then decomposed, and the 

 acid repeatedly crystallized. The mean results of several experi- 

 ments were 



Carbon .... 31-8 ... . 25 atoms 



Azote 18-5 6 - 



Hydrogen . . 1-4 ... . 6 - 

 Oxygen 48-3 15 - 



100-0 3008-9 1000 



The conversion of indigotic into carbazotic acid may be explained 

 by the abstraction of the elements of oxalic acid and ammonia from 

 the former, and the addition of nitric acid : this will give the exact 

 composition of carbazotic acid. When carbazotic acid is boiled with 

 a concentrated alkaline solution, much ammonia is evolved, and a 

 salt of an intense red colour is obtained, much resembling that pro- 

 duced by the croconic acid of Gmelin. — Journal de Chimie Medicate, 

 October 1833. 



MODE OF OBTAINING AZOTE IN ANALYSES. 

 M. Dumas obtains the azote from substances containing it by the 

 following process: The decomposing tube (in which oxide of cop- 

 per is used) is disposed as usual; but at its closed end there are 

 placed some grammes of carbonate of lead. After having exhausted 

 2 s 2 



