450 Notices of the Labours of Continental Chemists. 



H 2 CI 2 + Pt CI 4 . Consequently one atom of quinine, by taking 

 up four atoms of water and giving off C 4 O 4 produces two 

 atoms of quinoiline. This base also forms a crystalline double 

 salt with bichloride of mercury. New liquid bases are also 

 produced by acting with potassa on strychnine, narcotine, &c, 

 but the process is more complex. 



On Indigo-Nitric Acid (Indigotic Acid). 



Marchand instituted a series of experiments on this acid 

 with a view to determine its composition, without being aware 

 that Dumas was engaged on the subject: Marchand's results 

 have now been published, and they agree with those already 

 obtained by Dumas. He found the crystallized acid to con- 

 tain three atoms of water, two of which are given off at 150° C, 

 or by long exposure to a dry atmosphere. The third atom 

 is only displaced by bases. The formula of the hydrated acid 

 is C 14 H 8 N 2 O 9 + 3 H 2 O. The ammonia salt is anhydrous, 

 as is also the silver salt. Neutral indigo-nitrate of baryta was 

 obtained by boiling the acid with carbonate of baryta; it forms 

 shining needles which are difficultly soluble in cold water, 

 insoluble in alcohol and aether. It explodes when heated ; it 

 contains five atoms of water, of which it loses four at 200° C, 

 By boiling with caustic baryta or by the addition of ammonia 

 a basic salt is obtained. It contains two atoms of base and 

 five of water. The potassa salt is anhydrous. The formula 

 of the indigo-nitric acid has a great resemblance to those of 

 the salicyle series. Marchand endeavoured to trace the con- 

 nexion, and in the first place analysed some of the primary 

 compounds, because it was possible that the new atomic weight 

 of carbon might make some difference in their constitution. 

 His analyses of salicine, as well as those of Piria, Mulder, 

 Otto and Erdmann, agree very closely with the formula 

 C 28 H 38 O 15 , which explains the decompositions in a very 

 satisfactory manner; the formation of salicylous acid (hydu- 

 ret of salicyle) is very simple, C 28 H 38 O 15 = 2 (C 14 H 12 O 4 ) 

 + 7 H 2 O. Gerhardt has remarked that traces of salicylous 

 acid are formed among the products of the simple distillation 

 of salicine ; this method of preparing it is not, however, advan- 

 tageous, inasmuch as very little is obtained. The best process 

 is that of Piria as modified by Ettling. Three parts bichromate 

 of potassa, three parts salicine, four parts and a half sulphuric 

 acid, and thirty-six water. After twenty parts have passed 

 over, twenty parts of water may be added and again distilled 

 off. Marchand confirmed Piria's formula lor salicylous acid, 

 viz. C 14 H 12 O 4 . Salicylic acid may be obtained by fusing 

 salicylite of potassa with excess of potassa, or at once from 



