Fluid in the Ascidia of Nepenthes. 135 



Basic acetate of lead, as already mentioned, throws down from 

 the solution a white precipitate. I could not observe that this pre- 

 cipitate melted below the boiling-point of water, as pure malate of 

 lead does, but it must be remembered that this reaction is di- 

 stinctly marked only when the malate of lead is pure ; admixtures 

 of other salts of lead prevent it altogether ; and as I have shown 

 the presence of citric acid and another organic substance which 

 is thrown down by basic acetate of lead, there can be no doubt 

 that this was the reason why the precipitate did not dissolve in 

 boiling water. 



Though I have not been able to obtain a sufficient quantity of 

 the acids of Nepenthes for an elementary analysis, I think the above 

 reactions prove the presence of malic and citric acid. Oxalic acid, 

 which is readily detected, as the weakest solution of an oxalate is 

 thrown down by lime-water, I failed to discover; on the contrary, I 

 have shown that the water contained lime, which excludes the co- 

 existence of oxalic acid in a clear liquid. I have found that the 

 smallest quantity of oxalic acid immediately caused the water of 

 Nepenthes to become turbid. 



The second half of the residue left on evaporation of the mixed 

 fluids I exposed to a red heat in a platinum capsule. It turned 

 black, gave off pungent fumes, and left a white salt after all the 

 charcoal was burnt off. 



On analysis this residue was found to consist of 



Chloride of potassium 76*31 



Carbonate of soda 16*44 



Lime 3*94 



Magnesia 3*94 



100*63 



The unburnt residue left on evaporation of the fluid in the 

 ascidia of Nepenthes therefore consists, if we take the average of 

 the loss of the three determinations at 31*61 per cent, and reject 

 the carbonic acid of the ash, of — 



Organic matter, chiefly 



Malic acid and a little citric acid . 38*61 



Chloride of potassium .... 50*42 



Soda 6*36 



Lime 2*59 



Magnesia 2*59 



100*57 

 It is remarkable that none of the fluids which I examined 

 contained any sulphuric acid, which acid has been found in all 

 juices of plants, and which I do not doubt also exists in the sap 



