Dr. Hofmann on the Metamorphoses of Indigo. 397 



gave 0*5290 grm. of carbonic acid and 0*1365 grm. of water. 

 These numbers correspond in the 100 parts to 



Carbon . . . . =41*87 



Hydrogen . . . = 4*40 



The formula is SO3, Ci^/^fTN + HO, which gives 



Carbon . . . . = 40*75 

 Hydrogen . . . = 3*96 

 The excess of carbon arises from the formation of a small 

 quantity of deutoxide of nitrogen, which almost always takes 

 place in the combustion of such bodies, if a very considerable 

 quantity of copper turnings is not placed at the fore part of 

 the combustion tube. I did not think it necessary to repeat 

 this analysis, as it was only intended to give a view of the con- 

 stitution of the salt. 



BinoxalateofChloraniline,'2C^OQ,C^A q^ rN-f HO + 2aq. 



By dissolving crystals of chloraniline in a warm watery 

 solution of oxalic acid, a salt separates on cooling, which by 

 re-crystallization from hot water is obtained in long needles 

 like saltpetre. These consist of closely agglomerated prisms, 

 and hence could not be used for the determination of the cry- 

 stalline form. The salt is difficultly soluble in cold water and 

 alcohol. It is without smell, but possesses a sweetish burn- 

 ing taste. Its solution becomes coloured on exposure to the 

 air, and deposits gradually a red powder. The following re- 

 sults were obtained on burning this compound with chromate 

 of lead : — 0*4475 grm. gave 0*6990 grm. of carbonic acid 

 and 0*171 grm. of water, or in the 100 parts, 



Carbon . . . . = 42*59 

 Hydrogen . . . = 4*24 

 These numbers give the following formula : — 



2 C2 O3, C.^^fj N + HO + 2 aq. 



Theory. Found. 



A 



16 equiv. of Carbon. . =1200*00 42*37 42*59 



9 ... Hydrogen. = 112*50 3*97 4*24 



1 ... Chlorine . = 442*65 

 1 ... Nitrogen . = 177*04 

 9 ... Oxygen. . = 900*00 



2832^ 

 To control this formula I determined the amount of oxalic 

 acid in the salt. 0*339 grm. of the salt, saturated with am- 



