2£2 Comparative Analysis of 



. 3. It was insoluble in water, but very soluble in alcohol 

 and in liquid potash. 



4. When a lighted candle was applied to it, it burned 

 with a brisk flame. 



l'Voin the above it is evident that this substance was the 

 resinous part of the aloes. It is also very remarkable, that 

 this great quantity of resin, joined to the other parts of the 

 aloes, is easily soluble in warm water; but it is separated 

 from it on cooling. 



b.) The aqueous solution, which contained three ounces 

 of dissolved parts, acted in the following manner: — 



1. It was perfectly transparent, or' a golden ye' low colour : 

 when placed in contact with the air, it became of a brown 

 colour, but without being turbid. 



2. It reddened turnsole paper. 



3. The alkalis and the alkaline carbonates deprived it 

 of the property of reddening the blue colours, but these 

 solutions produced no other changes in it. 



4. Some drops of muriate of iron at the maximum pro- 

 duced a black colour. 



5. The nitrates of silver and of lead disturbed it slightly j 

 nitric acid restored its transparency to the liquor. 



6. The sulphuric, nitric, and muriatic acids precipitated 

 from it a small quantity of a yellow powder, which acted 

 like a resin, and which did not exceed 0-02. 



7. A solution of animal gelatine experienced no change 

 in it. 



c.) The aqueous solution was evaporated to dryness in 

 the sand-bath : there remained a mass similar to aloes, and 

 of a bitter taste. It was completely dissolved in hot or 

 cold alcohol. 



Ether which was digested with part of this powder was 

 not coloured with it, and did not dissolve a single atom of 

 it. 



These properties induced the author to take that part of 

 the aloes for the principle which M. Hermstadt designated 

 by the name of saponaceous principle, or soap of plants ; the 

 essential character of which is solubility in water and in 

 alcohol, but insolubility in ether. 



This saponaceous principle is found in several vegetables, 

 as in saffron, rhubarb, &c. : it is nevertheless probable that 

 there are different species of a more or less bitter taste. 



Action of Alcohol, a.) Four ounces of aloes were di- 

 gested with 16 ounces of alcohol. The solution was com- 

 plete, and there only remained on the filter 12 grains of lig- 

 neous matter which was contained in the aloes. 



b.) The 



