134 Dr. A. Voelcker on the Chemical Composition of the 



solved readily in water and alcohol, leaving behind a trace of a 

 brown organic matter. 



Lime-water added in excess to a portion of the acid solution 

 produced no precipitate in the cold, but on boiling a small white 

 precipitate fell down which redissolved entirely in sal ammoniac. 



Chloride of calcium and ammonium left the liquid unchanged 

 in the cold, but on boiling a precipitate was formed which was 

 soluble in sal ammoniac. 



Acetate of lead gave a white precipitate insoluble in ammonia, 

 soluble in acetic acid. 



Basic acetate of lead added to the liquid filtered from the pre- 

 cipitate caused by neutral acetate of lead produced another abun- 

 dant white precipitate. From these reactions it appears that the 

 precipitate with lime-water was caused by citric acid and not by 

 tartaric or racemic acid, the reactions of which acids are similar 

 to those of citric acid, for tartrate of lime is not soluble in sal 

 ammoniac, whilst tartrate of lead redissolves readily in ammonia. 

 Tartaric acid moreover is sufficiently characterized by the sparing 

 solubility of its acid potash salt, and as the acid liquid did not 

 give rise to the formation of such a salt with potash, we have 

 another indirect proof of the presence of citric acid. A little 

 tartaric acid added to the liquid in which tartaric acid was sought 

 in vain, after a few minutes produced the sparingly soluble pot- 

 ash salt. 



Racemic acid is thrown down both by lime-water and by a 

 solution of gypsum ; the acid liquid of Nepenthes remained un- 

 changed by either reagent, hence it cannot have contained any 

 racemic acid. 



The precipitate caused by chloride of calcium and ammonia 

 and boiling was filtered hot, and alcohol and ammonia added to 

 the clear liquid. The addition of alcohol produced a voluminous 

 white precipitate, a reaction which indicates the presence of malic 

 acid. The quantity of this precipitate was much larger than that 

 of the lime precipitate which citric acid gave. The formation of 

 a precipitate, upon addition of alcohol to the liquid from which 

 the first had been separated by filtration, is characteristic of the 

 presence of malic acid, for no other lime-salts were present ; for 

 instance, no sulphate of lime was present which could have pro- 

 duced a precipitate. But I thought it nevertheless necessary 

 to examine the precipitate caused by the addition of alcohol 

 further. When burnt it turned black, gave off pungent vapours, 

 and was converted into carbonate of lime. The solution of chlo- 

 ride of calcium and ammonia used for the experiment remained 

 clear after the addition of alcohol ; the acid liquid likewise re- 

 mained clear when alcohol was added ; both put together imme- 

 diately produced a white voluminous precipitate. 



