trated, 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 two 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, and which, when the bottle was hastily inverted, fell through the spirit of wine in round drops, like a ponderous oil.

The supernatant spirit of wine being carefully decanted off, some distilled water was added to this thick fluid, by which it was wholly dissolved. This solution, exposed to the air, shewed phænomena exactly similar to those of the undiluted solution (D).

The decanted spirit being also left exposed to the air in a shallow glass vessel, did not, after many days, either deposit a sensible quantity of precipitate, or become gelatinous; but having evaporated nearly away, left a few drops of a liquor which made infusion of red cabbage green; and, on the addition of some pure marine acid, effervesced violently. No precipitate fell during this saturation with the acid; nor

did the mixture on standing become a jelly; and on the total evaporation of the fluid part, a small quantity of muriate of tartar only remained. The spirit of wine seems, therefore, to have dissolved merely a portion of superabundant alkali present in the mixture, but none of that united with Tabasheer.

(F) To different portions of this solution were added some pure marine acid, some pure white vitriolic acid, and some distilled vinegar, each in excess. These acids at first produced neither heat, effervescence, any precipitate, or the least sensible effect, except the vitriolic acid, which threw down a very small quantity of a white matter; but, after standing some days, these mixtures changed into jellies so firm, that the glasses containing them were inverted without their falling out.

This change into jelly equally took place whether the mixtures were kept in open or closed vessels, were exposed to the light or secluded from it; nor did it seem to be much promoted by boiling the mixtures.

(G) Some solution of mild volatile alkali in distilled water, being added to some of this solution, seemed at the first instant of mixture to have no effect upon it; but in the space of a second or two it occasioned a copious white precipitate.

(H) The flakes remaining on the glasses at (D) and (E) put into marine acid raised a slight effervescence, but did not dissolve. These flakes when taken out of the acid, and well washed, were found, like the original Tabasheer, to be white and opaque when dry; but to become transparent when moistened, and then to shew the blue and flame colour, § II. (A).

(I) The jellies (F), diluted with water, and collected on a filter, appeared to be the Tabasheer unchanged.

§ X. A bit of Tabasheer, weighing two-tenths of a grain, was boiled in 127 gr. of strong caustic volatile alkali for a considerable time; but after being made red hot, it had not sustained the least diminution of weight.

§ XI. (A) 27 gr. of Tabasheer reduced to fine powder, were put into an open tin vessel with 100 gr. of crystals of soda, and some distilled water, and this mixture was made boil for three hours. The clear liquor was then poured off, and the Tabasheer was digested in some pure marine acid; after some time this acid was decanted, and the Tabasheer washed with distilled water, which was then added to the acid.

(B) This Tabasheer was put back into the alkaline solution, which seemed not impaired by the foregoing process, and again boiled for a considerable time. The liquor was then poured from it while hot, and the Tabasheer edulcorated with some cold distilled water, which was afterwards mixed with this hot solution, in which it instantly caused a precipitation. On heating the mixture it became clear again; but as it cooled it changed wholly into a thin jelly; but in the course of a few days, it separated into two portions, the jelly settling in a denser state to the bottom of the vessel, leaving a limpid liquor over it.

(C) The Tabasheer remaining (B) was boiled in pure marine acid; the acid was then poured off, and the Tabasheer edulcorated with some distilled water, which was afterwards mixed with the acid.

(D) The remaining Tabasheer collected, washed, and dried, weighed 24 gr. and seemed not to be altered.

(E) The acid liquors (A and C) were mixed together, and saturated with soda, but afforded no precipitate.

(F) The alkaline mixture (B) was poured upon a filter, the clear liquor came through, leaving the jelly on the paper.

Some of this clear liquor, exposed to the air in a saucer, at the end of some days deposited a small quantity of a gelatinous matter; after some days more, the whole fluid part exhaled, and the saucer became covered with regular crystals of soda, which afforded no precipitate during their solution in vitriolic acid. What had appeared like a jelly while moist, assumed, on drying, the form of a white powder.

This powder was insoluble in vitriolic acid, and seemed still to be Tabasheer.

Some of this clear liquor, mixed with marine acid, effervesced; did not afford any precipitate; but, on standing some days, the mixture became slightly gelatinous.

(G) Some of the thick jelly remaining on the filter, being boiled in water and in marine acid, appeared insoluble in both, and seemed to agree entirely with the above powder (F).

With dry alkalies.

§ XII. (A) Tabasheer melted on the charcoal at the blowpipe with soda, with considerable effervescence. When the proportion of alkali was large, the Tabasheer quickly dissolved, and the whole spread on the coal, soaked into it, and vanished; but, by adding the alkali to the bit of Tabasheer in exceedingly small quantities at a time, this substance was converted into a pearl of clear colourless glass.

(B) 5 gr. of Tabasheer, reduced to fine powder, were melted in a platina crucible with 100 gr. of crystals of soda. The mass obtained was white and opaque, and weighed 40.2 gr. Put into an ounce of distilled water, it wholly dissolved. An excess of marine acid let fall into this solution produced an effervescence, and changed it into a jelly. This mixture was stirred about, and then thrown upon a filter. The jelly left on the paper did not dissolve in marine acid by ebullition; collected, washed with distilled water, and dried, it weighed 4.5 gr. and seemed to be the Tabasheer unaltered.

The liquor which had come through being saturated with mineral alkali yielded only a very small quantity of a red precipitate, which was the colouring matter of the pink blotting paper through which it had been passed.

(C) 10 gr. of Tabasheer, reduced to powder, were mixed with an equal weight of soda, deprived of its water of crystallization by heat. This mixture was put into a platina crucible, and exposed to a strong fire for 15'. It was then found converted into a transparent glass of a slight yellow

colour. This glass was broken into pieces, and boiled in marine acid. No effervescence appeared; but the glass was dissolved into a jelly. This jelly, collected on a filter, well washed and dried, weighed 7.7 gr.

The acid liquor which came through, on saturation with soda, afforded not the least precipitate; but, after standing a day or two, it changed into a thin jelly. This collected on a filter was washed with distilled water, and then boiled in marine acid, but did not dissolve. Being again edulcorated, and made red hot, it weighed 1.6 gr. The filtered liquor (B) would in all probability have changed similarly to a jelly, had it been kept. These precipitates were analogous to those § IX. (I).

(D) An equal weight of vegetable alkali and Tabasheer were melted together in the platina crucible. The glass produced was transparent; but it had a fiery taste, and soon attracted the moisture of the air, and dissolved into a thick liquor. But two parts of vegetable alkali, with three of Tabasheer, yielded a transparent glass, which was perma

nent.

Treated with other fluxes.

§ XIII. (A) A fragment of Tabasheer put into glass of borax, and urged at the blow-pipe, contracted very considerably in size, the same as when heated per se; after which it continued turning about in the flux, dissolving with great difficulty and very slowly. When the solution was effected, the saline pearl remained perfectly clear and colourless.

(B) With phosphoric ammoniac (made by saturating the acid obtained by the slow combustion of phosphorus with caustic volatile alkali) the Tabasheer very readily melted on the charcoal at the blow-pipe, with effervescence, into a white frothy bead.

(C) Fused, by the same means, on a plate of platina, with the vitriols of tartar and soda, it appeared entirely to resist their action; the little particles employed continuing to revolve in the fluid globules without sustaining any sensible