its Analysis of Aloes, 



gramme? of nitric acid at 36°, taking care to administer the 

 fire with caution. There was a brisk re-action, and libera- 

 tion of abundant red vapours. When they disappeared, the 

 retort was removed from the fire, and the liquor which it 

 contained was of a deep yellow colour. It deposited upon 

 cooling a great quantity of a flaky yellow substance. The li- 

 quor, when evaporated to the consistence of honey, was di- 

 luted in water and filtered. There remained in the filter a 

 vellow substance, which, after having been washed and dried, 

 formed one fourth of the aloes employed in the experiment. 

 I thought at first that this matter was a portion of the aloes 

 which had escaped the action of the nitric acid : but the fol- 

 lowing properties soon convinced me that it was an acid 

 with some analogy to the yellow acid, and the detonating 

 matter which Messrs. Fourcroy and Vauquelin obtained by 

 the action of the nitric acid on animal substances, but 

 which differs from it in several respects. 



The yellow aloetic acid, when well washed and dried, is of 

 a very fine yellow colour, and extremely bitter. It does not 

 crystallize, reddens blue turnsole paper, and effervesces 

 with the alkaline carbonates. , 



It has an agreeable aromatic smell, particularly when it is 

 gently heated. It melts like nitre, gives out an aromatic 

 vapour mixed with bitterness, and leaves an abundant charry 

 residue. 



When distilled at a gentle heat, it furnished all the usual 

 products of vegetable substances, and ended by detonating, 

 producing at the same time a purple flame. A very abun- 

 dant charcoal remained, forming the third part of the sub- 

 stance employed. 



This acid is not very soluble in water. It required two 

 hectogrammes and a half of this fluid at 10°-|-0 Reaumur to 

 dissolve entirely two decigrammes of it. This solution was 

 of the fine red colour of arterial blood. The muriate of tin 

 produced in it a precipitate of the colour of wine-lees, and 

 the sulphate of iron heightens the colour. 



Fifteen grammes of alcohol at 38° could only dissolve a 

 decigramme of this yellow acid, and the solution was of a 

 verv dvcp red colour. 



The mineral acids, warm, dissolve this yellow matter with- 

 out extricating any thing from it ; but it is soon deposited 

 afterwards on account of its insolubility. 



Potash forms with it a combination capable of crystal- 

 lizing, and of a deep-red. This red salt detonates with the 

 violence of gunpowder, either on exposing it to a certain 

 heat, or by touching it with a lighted coal, aod leaves after 



its 



