104 PHILOSOPHICAL TRANSACTIONS. [aNNO 1791. 



not seem by this treatment to suffer any change, and after having been freed 

 from all adhering vitriolic acid by boiling in water, it had not undergone any 

 alteration either in its weight or properties. The vitriolic acid afforded no precipi- 

 tate on being saturated with soda, (b) 2 gr. of tabasheer reduced to fine powder 

 were made into a paste with some of this same vitriolic acid, and this mixture 

 was heated till nearly dry ; it was then digested in distilled water. This water, 

 being filtered, tasted slightly acid, did not produce the least turbidness with 

 solution of soda, and some of it, evaporated, left only a faint black stain on the 

 glass, produced doubtless by the action of the vitriolic acid on a little vegetable 

 matter, which it had received either from the tabasheer, or from the paper. 

 The undisssolved matter collected, washed, and dried, weighed l.ggr. 



§ 8. 2gr. of tabasheer, reduced to fine powder, were long digested in a con- 

 siderable quantity of liquid acid of sugar. The taste of the liquor was not 

 altered; and being saturated with a solution of crystals of soda in distilled 

 water, it did not afford any precipitate. The tabasheer having been freed from 

 adhering acid, by very careful ablution with distilled water, and let dry in the 

 air, was totally unchanged in its appearance, and weighed l.QSgr. This taba- 

 sheer being gradually heated till red-hot, did not become in the least black, or 

 lose much of its weight, a proof that no acid of sugar had fixed in it. 



IVith liquid alkalis. — § Q. (a) Some liquid caustic vegetable alkali being 

 heated in a phial, tabasheer was added to it, which dissolved very readily, and 

 in considerable quantity. When the alkali would not take up any more, it was 

 set by to cool, but was not found next morning to have crystallized, or under- 

 gone any change, though it had become very concentrated, during the boiling, 

 by the evaporation of much of the water. 



(b) This solution had an alkaline taste, but seemingly with little, if any 

 causticity. 



(c) A drop of it changed to green a watery tincture of dried red cabbage. 



(d) Some of this solution was exposed in a shallow glass to spontaneous 

 evaporation in a warm room. At the end of a day or 1 it was converted into a 

 firm, milky, jelly. After a few days more, this jelly was become whiter, 

 more opaque, and had dried and cracked into several pieces, and finally it became 

 quite dry, and curled up and separated from the glass. The same change took 

 place when the solution had been diluted with several times its bulk of distilled 

 water, only the jelly was much thinner, and dried into a white powder. Some 

 of this solution, kept for many weeks in a bottle closely stopped, did not become 

 a jelly, or undergo any change. 



(e) a small quantity of this solution was let fall into a proportionably large 

 quantity of spirit of wine, whose specific gravity was .838. The mixture 

 immediately became turbid, and, on standing, a dense fluid settled to the bottom. 



