M. Trommsdorff 072 Gentianin, 221 



a fat substance, and the spot remains for shorter or longer time, ac- 

 cording to the temperature. It has a slight smell when totally freed 

 from acetic acid. This odour is peculiar, and not at all aromatic ; 

 it has a bitter taste ; its after taste is sharp, and resembles that 

 termed metallic. Its specific gravity at 47° Fahr. is 1*13 15; it is 

 slightly volatile, and reddens litmus paper strongly. 



The chemical properties of this acid are, that it boils between 122^ 

 and 13P Fahr,, and gives off pungent vapours which affect the eyes. 

 It is, however, less volatile than water and concentrated acetic acid ; 

 it becomes more viscid at a few degrees below 32°, and is nearly as 

 thick as soft butter. Light does not appear to act upon it ; the ac- 

 tion of the air is but little known. This acid, when kept in half- 

 filled bottles, appears to be converted into very concentrated acetic 

 acid, and a volatile product. Do these result from the absorption of 

 oxygen ? It combines with water in all proportions : *the solution 

 reddens litmus paper strongly. 



When mixed with liquid ammonia, it does not at first appear to 

 suffer any alteration ; but if the mixture be heated to 80'' Fahr., it 

 soon becomes of a brown colour ; if the temperature be raised to 

 IGO**, the colour becomes deeper and deeper; if it be then suddenly 

 cooled, a glutinous product is obtained, which is of a dark colour, 

 and in which numerous crystals may be perceived. This production of 

 this colour, says the author, I had attributed to the action of the heat ; 

 but having taken fresh portions of ammonia and the acid in the same 

 proportions, and left them exposed to the atmosphere in a watch- 

 glass, it became coloured in twenty-four hours, but no crystals were 

 formed. This mixture is volatile. Does this acid contain aldehyde } 

 Are the crystals the ammonaldehyde of Liebig ? In the absence of 

 proof, opinion should be suspended. I thought, at first, the brown- 

 coloured product the aldehydarz of Liebig: I then threw it into 

 water, and it dissolved totally without the slightest residue. 



When this acid is put into contact with fine crystals of nitrate of 

 mercury, the mixture becomes milk-white ; but if heated to a tem- 

 perature between 140° and 160°, ebullition occurs, vapours are given 

 off which affect the eyes very powerfully, and a globule of a greyish- 

 blue colour soon forms at the bottom. This globule, says M. Leroy, 

 seems to be cemented by a fatty matter, and on examining it with a 

 strong glass, small brilliant points were perceptible, which appeared 

 to be globules of mercury. When a lighted taper is presented to 

 this acid, it burns with a white flame. — Journal de Chimie Medicale, 

 December 1837. 



ON GENTIANIN. BY M. TROMMSDORFF. 

 MM. Henry and Caventou, in 1821, first separated a crystalli- 

 zable substance from gentian root. They attributed all the bitterness 

 of the plant to it, and CEdled it gentianin. This substance was a 

 mixture. According to TrommsdorfF, it may be obtained pure by the 

 following process. Treat two pounds of gentian root with aether 

 till it ceases to dissolve anything ; the greater part of the aether is 

 to be separated by distillation, and the remainder is to be treated 



