AKALYSlS OP ALOES. 369 



Tf" hey did not find aloes soluble in cold water like Mr. Only In part 

 Braconnot. On a quantity of succotritle aloes in powder 



dissolved by- 

 cold water. 



they poured water at S'^ R. [50T], assisting its action by 

 frequent stirring. The clear supernatantliquor, after settling, 

 was deicanted off, and another quantity of water poured on 

 the residuum. This Ayas repeated, till the water, after 

 standing on the residuum four and twenty hours, was found 

 destitute both of taste and colour. The glutinous matter 

 remaining Avas then worked between the fingers under, a 

 stream of water. 



The first liquor poured off was very brown, and strongly 

 impregnated with the aloes ; the second and third were much 

 less so, t!ie rest growing weaker in succession, till the 

 last was clear water. When the aloes had been sufficiently Insoluble part,- 

 washed, and thus exhausted by water at 8'' [SO^^F.], there 

 remained a soft grayish mass, very elastic, which, when 

 ■wet with w^ater, did not stick to the fingers. 



The aqueous solution of aloes, as Trommsdorff ob- Two dlPFcrent 



, , ^ ,1 . I 1 , . substances in 



served, evaporated gently to dryness, leaves a substance ^-^jj^^^ 

 soluble in water and alcohol, but scarcely at all in ether. 

 The r-eginous matter of aloes, on the contrary, is soluble 

 in alcohol and in ether, but not in water at 10° [54*5°F,] 

 The former dissolves readily in cold nitric acid at 36°, and 

 forms a green liquid, which is scarcely rendered turbid oa 

 the addition of a little water, and becomes perfectly clear 

 when farther diluted. The resinous part is more difFicultly 

 acted on by this acid, and produces a red solution, which, 

 though much weaker than the former, throws down a 

 resinous, sticky, insoluble substance, on the addition of a 

 little water. 



Nitric acid heated on aloes produced a fine ycllov/ powder, Action of nitric 

 and nearly the same phenomena as those observed by Mr.*^' " 

 Braconnot. This powder, dilfused in a little water, com- 

 municated to it a superb purple, very rich in colour. A ^''^e purple 

 singic atom will tinge a very large quantity of watery ' '" 

 This colour is so permanent, that the skin remains dyed 

 with it for several days, particularly if an alkaline salifiable 

 base have been previously added to the powder. 



Messrs. B. L. and V. likewise passed a cur:e!it of osi- Aciinn of oxi- 

 ijinriatic acid gas into a concentrated solution of aloes ;„ '"""^"'■-^'•' 

 • Vol. XXVIl.— SuppLrMFNT. Bb cold 



