Analysis of Atoms', 22 f 



it a precipitate very abundant in comparison of that which 

 is produced in the recent solution of aloes. 



These facts, in my opinion, amply prove that aloes does 

 hot constitute a species of the resins. 



§ IV. Alcohol at 38° entirely dissolves aloes very speed- 

 ily, particularly if heat be employed; which announces the 

 absence of gummy or extractive matter in this substance. 

 The filtered liquor was of such a deep red colour that its 

 transparency could scarcely be perceived : water produces an 

 abundant sediment in it of a pale vellow colour, owing to 

 this liquid which is retained in it, for it resumes its primi- 

 tive brown colour on desiccation. 



If we evaporate the alcoholic solution of aloes, we re- 

 mark that the least motion* the slightest breathing on the 

 liquid, produces a kind of crystallization in it, which dis- 

 appears and then is reproduced. Although alcohol dissolves 

 this substance very well, this is not the case with the fixed 

 and volatile oils. I exposed to heat a mixture of oil of olives 

 and aloes, and this last substance remained in a melted state 

 at the bottom : the essence of turpentine, which I boiled with 

 the aloes, acted nearly in the same manner: the volatile 

 oil nevertheless assumed a slight amber colour. 



§ V. Alkaline solutions dissolve aloes cold and with 

 much facility: combinations are formed in which the bit- 

 terness seems in some measure marked. Acids produce 

 in these solutions abundant precipitates which are coloured 

 on desiccation. The volatile alkali diluted in water, also 

 dissolves aloes perfectly : after having filtered the liquor, it 

 was of a deep red colour : and it was evaporated slowly, to 

 drive off the excess of ammonia. In proportion as this liquor 

 was thickened the surface exhibited a continual motion, 

 which seemed to indicate a tendency to crystallization ; for 

 we remarked other needles which successively appeared and 

 disappeared. On continuing the evaporation almost, to 

 dryness, we obtained crystals in needles attached to a resi- 

 nous-like mass : on heating this matter with a ce'rtain quan- 

 tity of lime and water, a very evident extrication of am- 

 monia takes place. 



§ VIvThe weak acids have not a very remarkable action 

 upon aloes : nevertheless they dissolve it better than water, 

 which whitens the solution of aloes in distilled vinegar. 

 The mineral acids act much more energetically upon it. 

 NitTic acid dissolves it very well when cold, and there re- 

 sults a deep red liquor, from which water throws down an 

 abundant precipitate. 



Ten grammes of aloes were treated in a retort with eighty 



P 2 gramme* 



