of a newly discovered vegetable acid. 24,9 
“ Saturate the juice of apples, whether ripe or unripe, with 
carbonate of potash ; add solution of acetate of lead until 
it cease to produce a precipitation. To the edulcorated 
precipitate, add as much dilute vitriolic, acid, as is necessary 
to give the mixture a perfectly acid taste, without any sweet- 
ness/'* 
There are several objections to this process, all of which 
seem to have considerable weight. In the preceding pages I 
have shown, that the juice of apples, whether ripe or unripe, 
always contains two acids of very different properties. By 
the above process these acids are not separated ; they are in 
fact found in what is supposed to be the resulting pure malic 
acid, and it is impossible, without the most complicated pro- 
cesses, to obtain this substance in the insulated form. 
The precipitation of the lead by means of sulphuric acid, 
appears to be objectionable. I have often attempted to adjust 
the proportion of the latter substance, so as to throw down all 
the lead, without leaving any free sulphuric acid, but I uni- 
formly failed : and it is evident, that, if not impossible, it is 
exceedingly difficult and troublesome. 
Scheele also attempted to obtain malic acid from malate 
of lime, by means of sulphuric acid, but found “ the mode 
rather difficult, as the acid would not let the calx fall com- 
pletely.” Vauquelin observed the same thing. 
The last process proposed by Scheele, is to distil equal parts 
of weak nitric acid and sugar, until the mixture become brown, 
which is a sign that all the nitrous acid has been abstracted : 
the oxalic acid formed, is to be separated by lime water, and 
the remaining acid to be saturated with carbonate of lime. 
* Crell’s Chemische Annal. 1785. Vol. II. 295. 
MDCCCXV. Kk 
