24b Mr* Davy’s Experiments and Observations 
was of a dark-brown colour, and became green at the surface, 
when it was exposed to the air. It gave no precipitate to solu- 
tion of gelatine ; and afforded only an olive-coloured precipi- 
tate with the salts of iron. 
When muriatic acid was poured into the clear fluid, a violent 
effervescence was produced ; the fluid became turbid ; a precipi- 
tate was deposited ; and the residual liquor acted upon gelatine and 
the salts of iron, in a manner similar to the primitive infusion. 
M. Deyeux, in distilling the precipitate from infusion of galls 
by carbonate of potash, obtained crystals of gallic acid. In fol- 
lowing his process, I had similar results ; and a fluid came over, 
which reddened litmus-paper, and precipitated the salts of iron 
black, but did not act upon gelatine. 
When the precipitate by carbonate of potash was acted upon 
by warm water, applied in large quantities, a considerable por- 
tion of it was dissolved ; but a part remained, which could not 
in any way be made to enter into solution ; and its properties 
were very different from those of the entire precipitate. It was 
not at all affected by alcohol : it was acted on by muriatic acid, 
and partially dissolved; and the solution precipitated gelatine 
and the salts of iron. It afforded, by incineration, a considerable 
portion of lime, but no alkali. 
In comparing these facts, it would seem, that the precipitate 
from infusion of galls, consists partly of tannin and gallic acid 
united to a small quantity of alkali, and partly of these vegetable 
matters combined with calcareous earth ; and it will appear pro- 
bable, when the facts hereafter detailed are examined, that both 
the potash and the lime are contained in these compounds in a 
state of union with carbonic acid. 
The solutions of carbonate of soda and of carbonate of 
