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



On burning, the 0-82 of a grain lost 0*27 of a grain, or 

 100 parts lost 32'92 per cent. 



All the liquids from the different localities above-mentioned 

 which were left over I mixed together and evaporated the mix- 

 ture to dryness. One-half of the dry residue I exposed to a red 

 heat, and used the remaining white ash for the determination of 

 the inorganic salts of which it was composed. 



The other half I dissolved in water and precipitated with basic 

 acetate of lead, in order to obtain the organic acids in combina- 

 tion with lead. This precipitate I collected on a filter and washed 

 with cold distilled water. It was then removed from the filter 

 and suspended in water, through which a current of sulphuretted 

 hydrogen was passed. By this means I separated the lead as 

 sulphuret, and obtained the organic acids free dissolved in water. 

 This solution was colourless and very acid ; evaporated to a small 

 bulk in a water-bath it assumed a yellow colour, and dried at last 

 to a yellow crystalline mass, which deliquesced in the air and dis- 

 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 



