516 Experiments and Olservat'iovs on the 



astringent ; but it leaves in the mouth, for some time, a 

 sensation of sweetness stronger than that given by the ca- 

 techu itself. 



Its solution in water is at first yellow brown ; but it gain^ 

 a lint of red by exposure to the air. Its solution in alcohol 

 does not materially change colour in the atmosphere j and 

 it is of an uniform dull brown. 



The cxlractive matter, whether solid or in solution, was 

 not found to produce any change of colour upon vegetable 

 blues. 



It became of a brighter colour by the action of the al- 

 kalis ; but it was not precipitated from its solution in water 

 by these bodies, nor by the alkaline earths. 



The aqueous solution of it, when mixed with solutions 

 of nitrate of alumine and of muriate of tin, became slightly 

 turbid. 



To nitrate of lead it gave a dense light brown precipita- 

 tion. 



Is was not perceptibly acted upon by solution of gela- 

 tine ; but, when solution of sulphate of alumine was added 

 to the mixture of the two fluids, a considerable quantity of 

 solid matter, of a light brown colour, was innnediately de- 

 posited. 



To the solution of oxygenated sulphate of iron it com- 

 nm'nicated aliffe grass green tint; and a green precipitate 

 vas deposited, which became black by exposure to the air. ■ 

 It was not precipitated by the mineral acids. 

 Linen, by being boiled in the strongest solution of the 

 extractive matter, acquired a light red brown tint. The 

 liquor became almost colnurlcss ; and, after this, produced 

 very little chaijge in the solution of oxygenated sulphate of 

 iron. 



Raw skin, prepared for tanning by being immersed in 

 the strong solution, soon acquired the same kind of tint as 

 the linen. It united itself to a part, of -the extractive mat- 

 ter ; but it was not rendered by it insoluble in boiling water-. 

 The solid extractive matter, v/hen exposed to heat, soft- 

 ened, and became darker in its colour, but did not enter 

 .into fusion. At a temperature below that of ignition, it 

 was decompounded. The volatile products of its decom- 

 position were, carbonic acid, hydrocarbonate, and water 

 holding in solution acetous acid and a little unaltered ex- 

 tractive matter. There remained a light and very porous 

 charcoal. 



In considering the manner in which the catechu is pre- 

 parody it would be reasonable to conclude that diflerent spe- 

 cimens 



