254 AT/'. Davy's Experiments and Observations 
poured into the infusions, copious precipitates, of a shade of light 
brown, were formed ; and the residual fluid assumed a paler 
tint of red, and was found to have lost its power of precipitating 
gelatine. 
After lime had been boiled for some time with a portion of 
the infusion, it assumed a dull red colour. The liquor that 
passed from it through the filtre had only a faint tint of red, 
did not act upon gelatine, and seemed to contain only a very 
small portion of vegetable matter. Pure magnesia, when heated 
with the infusion, acted upon it in an analogous manner; the 
magnesia became light red, and the residual fluid had only a 
very slight tinge of that colour. With carbonate of magnesia, 
the infusion became deeper in colour, and lost its power of pre- 
cipitating gelatine; though it still gave, with oxygenated sulphate 
of iron, a light olive precipitate. 
The carbonates of potash, of soda, and of ammonia, in their 
concentrated solutions, produced only a slight degree of turbid- 
ness in the infusion of catechu : they communicated to them a 
darker colour, and deprived them of the power of acting upon 
gelatine ; though this power was restored by the addition of an 
acid. 
After the mixture of the solution of carbonate of potash and 
the infusions had been exposed to the atmosphere for some 
hours, a brown crust was found to have formed upon its surface, 
and a slight precipitation had taken place. 
The salts of alumine precipitated the infusions, but less co- 
piously than they precipitate the infusion of galls. A similar 
effect was produced by nitrate of potash, sulphate of magnesia, 
prussiate of potash, and many other neutral salts. 
