ACTION OF NITRIC ACID ON INDIGO. Q^ | 



VI. 



Abstract of a Paper on the bitter Substances formed by the 

 Action of Nitric Acid on Indigo : by Mr. Chevukul *. 



§1. 1. IJEFORE I recite my experiments on the bitter Action of nitric 

 and acid substances, that are obtained by treating indigo ^"^ °'^ '"^'8" 



. . ' •' CO examined. 



With nitric acid, I will briefly advert to the labours of 

 others on the same subject at ditferent periods. 



2. Mr. Haussman was the first, who rhade known the for- Amerfrom it 

 mation of the iVitter principle by the action of nitric acid 



on indigo. Mr. Welther afterward obtained it from silk by and from sillv. 

 means of the same acid, described iis principal projicrties, 

 and gave it the name of amer. 



3. Messrs. Proust, Fourcroy, andVauquelln, have shown Almost all 

 in several papers, that almost all organic substances, into """g^'nf si'b- 



, .;',.,. . . , T.r . , stances yield it, 



the composition of which nitrogen enters, yield VVelther's and frequently 



amer, and frequently benzoic acid. benzoic acid. 



Messrs. Fourcroy and Vauquelin studied with great at- Properties of 



tention the properties of the amer obtained with indigo, 'f^^' -iccording 

 ^ * . ° to ton re roy and 



They observed, that it was acid; and that it was to be con- Vauquelin. 



sidered as a superoxigcnated hydrocarburet of nitrogen, 



forming with pure potash a detonating compound, which 



appeared not to contain any nitric acid, as Welther had 



said. They observed farther, that, if the action of the 



nitric acid on the indigo was stopped, before the whole of 



the amer was formed, an acid was obtained, which sublimed 



In -white acicular crystals, and appeared much to resemble 



benzoie acid. 



4. Mr. Ilatchett, in his learned researches concerning the Mr. iiatchett'i ' 

 action of sulphuric and nitric acids on vegetable compounds, ^'^I'i'^ialwnnui, 

 made known several products, that precipitate gelatine 



as tannin does: and on account of this property, com- 

 bined with several others, he called them artificial tanning 

 matter. 



5. I observed in the year 1808, that the extract of Brazil Action of nun.. 

 wood was converted by nitric acid into a bitter substance, ^^^^ oabrazil, 



* Ann. de Chim. vol. Ixxti, p. 113. Read to the National In- 

 stitute, tlieSOthof Nov., 1809. 



that 



