242 Mr. Davy’s Experiments and Observations 
infusion. At first, a faint turbid appearance was perceived ; but, 
by agitation, the fluid became clear, and its colour changed from 
yellow brown to brown red ; and this last tint was most vivid 
on the surface, where the solution was exposed to the atmo- 
sphere. The solution of isinglass did not act upon the infusion 
modified by the alkali, till an acid was added in excess, when a 
copious precipitation was occasioned. 
The compound of potash and solution of galls, when eva- 
porated, appeared in the form of an olive-coloured mass, which 
had a faint alkaline taste, and which slowly deliquesced when 
exposed to the air. 
■ Soda acted upon the infusion in the same manner as potash; 
and a fluid was formed, of a red-browm colour, which gave no 
precipitate to gelatine. 
Solution of ammonia produced the same colour as potash and 
soda, and formed so perfect an union with the tannin of the 
infusion, that it was not acted upon by gelatine. When the 
compound liquor was exposed to the heat of boiling water, a 
part of the ammonia flew off, and another part reacted upon 
the infusion, so as to effect a material change in its properties. 
A considerable quantity of insoluble matter was formed ; and 
the remaining liquor contained little tannin and gallic acid, but 
a considerable portion of a substance that precipitated muriate 
of tin, and the salts of alumine. 
When the experiment on the ebullition of the compound of 
the infusion and ammonia was made in close vessels, the liquor 
that came over was strongly impregnated with ammonia; 
its colour was light yellow, and, when saturated with an acid, 
it was very little altered by the salts of iron. The residual fluid, 
after the process had been continued for some time, as in the 
