Gallic Acid. 
12. No action on salts of zinc. 
13. Ditto, with nitrate of silver 
and salts of manganese. 
14. No action on mercurial 
salts. 
15. No effect on sulphate of 
iron at the instant of mixture; 
but the colour becomes ame- 
thystine, blackens in 24 
hours, and lets fall a black 
precipitate. 
16. Persulphate of iron thrown 
down of a deep blue. 
17. Forms brown precipitates, 
Historical Sketch of the Physical Sciences, 1818. 
Juice of the Fruit of Gingko. 
12. Forms white precipitates in 
all the salts of zinc. 
13. Precipitates nitrate of sil- 
ver and salts of manganese 
white. 
14. A white precipitate in cor- 
rosive sublimate, and a ca- 
nary yellow ditto in nitrate 
of mercury. 
15. Ditto ; only the precipitate 
is not black, but continues 
amethystine. 
16. Ditto precipitated green, 
and the liquidremains green, 
17. Gives permanent brown 
with nitrate and muriate of 
iron, which redissolve, and 
give a brown colour to the 
liquid. In. acetate of iron 
forms a very light black pre- 
cipitate, which remains sus- 
pended several days. 
precipitates m the nitrate 
and muriate of iron. With 
acetate of iron exhibits the 
same phenomena as gallie 
acid does. 
(Bibl. Univers. vii. 29.)— 
I think these experiments hardly warrant the inference drawn 
by M. Peschier, that this juice contains a peculiar acid. It is 
much more likely that the acid present is the gallic, and that the 
variations observable in the preceding table are owing to the 
presence of some other vegetable bodies in the juice of the 
gingko, which are of course wanting in the solution of gallic acid. 
Before the peculiar nature of this acid be established, it must be 
obtained in a separate state, and it must be shown that in that 
state it contains peculiar properties. 
10. Meconic Acid.—This acid was first recognized by Sertiir- 
ner in opium ; but his account of it was defective, and on that 
account doubts have been thrown by some chemists upon its 
peculiar nature. M. Choulant has given us a very simple mode 
of preparing it, which will easily put it in the power of other per- 
sons to verify the statements of Sertiirner respecting it. The 
process is as follows : 
The infusion of opium is to be freed from morphia, and care 
must be taken that it does not contain any excess of ammonia. 
Into this infusion muriate of barytes is to be poured as long as 
‘any precipitate continues to fall. The precipitate, when well 
washed and dried, is pure meconate of barytes. Let it be tritu- 
