of a neu'hj -discovered vegetalle Acid. 435 



acid was left dissolved in the liquor. The first washing con- 

 tained most free acid, and therefore suffered least of the neutral 

 salt to crystallize. 



The red acid liquor, as has been stated, contained much lead, 

 and this it was necessary to separate. The most unexcep- 

 tionable method appeared to be the transmission of sulphuretted 

 hvdrogen through tlie clear liquor. This was accordingly done, 

 after having heated the acid liquor so as to redissolve the crystals 

 and sediment. The resulting sulphurct of lead was filtered off, 

 and the clear fluid was boiled for a length of time, to expel the 

 superfluous gas. 



Supposing now that I had obtained the pure acid, I began 

 to form various conjectures as to its nature; in the midst of 

 which I discovered that the berries of the Sorbite uucuparia 

 had already occupied the attention of Scheele, and that he had 

 pronounced their acid to be the malic. There was indeed a 

 great coincidence of properties between the two acids: malic 

 acid is red, when evaporated to dryness it deliquesces, its 

 combinations with potash, soda, and ammonia are deli(j\iescent; 

 such were also tlie properties of the acid under consideration. 

 Yet 1 had never understood that malate of lead could be made 

 to afford crystals : an experiment on this head, therefore, be- 

 came necessaiy. 



The juice of nearly ripe apples was saturated with potash, 

 and the solution when filtered was mixed with solution of acetate 

 of lead : the precipitate was collected on a filter. This after 

 being edulcorated was washed with boiling water, as before. In 

 sixteen hours, crystals, precisely the same as the berries had af- 

 forded, were deposited, although less in quantity. 



The production of crystals in both these cases seemed to 

 show that the acid of both fruits was the same: yet there was 

 one difference. The precipitate remaining on the filter, after 

 the action of boiling water, was, in that produced from apples, 

 soft and pasty; but that obtained from the Snrbus berries was 

 hard and dense. It became therefore necessary, to discover 

 what would be th& habitudes of malate of lead obtained by other 

 means. 



Scheele showed that the primary action of nitrous acid on 

 sugar is to form malic acid. I therefore heated together equal 

 weights of these substances, until the effervescence ceased. The 

 brown residue was diluted with lime-water, and when the oxalic 

 acid that might have been formed was in this manner scjjarated, 

 the remaining acid substance was saturated with potash. Acetate 

 of lead was addea, and the malate of lead thus formed was col- 

 lectc<l and edulcorated. 



It now remained to ascertain whether this malate possessed 

 E c 2 the 



