Of the Action of Vegelalle Acids on Alcohol. 433 



the preceding ; yet to be quite certain I resolved to submit 

 some of ihem to a rigorous trial, and for the purpose I 

 made choice of the gallic, tartaric, and acetic acids, the other 

 acids being either difficult to procure or insoluble in alcohol. 



The experiment with the gallic acid had not that success 

 I desired, because I operated on no more than 10 grammes 

 of acid: the combination was always produced; for, after 

 havina; distilled these 10 grammes of gallic acid with 12 of 

 alcohol and 4 of sulphuric acid until half the original quan- 

 tity of the mixture remained, I found in (he retort a liquor, 

 which, when covered with water and saturated with potash, 

 gave me, by a fresh distillation, all the free alcohol it con- 

 tained, and which, when mixed with potash in excess, 

 afforded me another portion : this last could alone be that 

 which was combined with the gallic acid. 



On the contrary, with the tartaric acid the experiment 

 completely succeeded, and furnished some curious results. 

 Here, I employt-d as before wiih the oxalic acid 30 grammes 

 of the vegetable acid, 35 of pure alcohol, and 10 of con- 

 centrated sulphuric acid. The distillation was carried on 

 till a little ether began to he formed • at this period the fire 

 was lowered in the furnace, and the retort allowed gradually 

 to cool. The liquor, whilst cooling, assumed the consist- 

 ence of a thick syrup. I poured water on it, but in vain, 

 with the hope of separating, as in the preceding experiments, 

 the peculiar combination of acid and alcohol : then, having 

 successively added to this liquor different quantities of pot- 

 ash, a large precipitate was formed of the acidulous tar- 

 trate of potash ; and having saturated it without passing the 

 neutral point, having evaporated it, and subjected it when 

 cold to strongly concentrated alcohol, I obtained, by eva- 

 porating the alcoholic solution, a substance which, when 

 cool, became of the consistence of thick jeliy, and even 

 with greater ease than before; it was treated with potash 

 and alcohol. 



This substance is of a brownish colour, and is slightly 

 bitter, nauseous, inodorous, IVee from aciditv, and very 

 SoKiblc in water and alcohol ; it does not precipitate muriate 

 of lime, but abundantly the muriate of barytcs : daring cal- 

 cination it emits dense fumes possessing a strong smell of 

 garlic ; at the same time it leaves no alkaline but a car- 

 bonaceous re.-idue, which contains a considerable quantity 

 of sulphate of potash: in a wovd, when it is distilled with 

 potash, plenty of alcohol and a large quantity of tartrate 

 t»f potatli ure txiractcd from it. Jticncc it is evident ibat 

 I', e 2 ^h» 



