108 PHILOSOPHICAL TRANSACTIONS. [aNNO IJQl- 



(e) Tlie ease with which this substance had melted with vegetable ashes, led 

 to the trial of it with pure calcareous earth. A fragment of tabasheer, fixed to 

 the end of a bit of glass, was rubbed over with some powdered whiting. As 

 soon as exposed to the flame of the blow-pi[)e, it melted with considerable effer- 

 vescence; but could not, even on the charcoal, and with the addition of more 

 whiting, be brought to a transparent state, or reduced into a round bead. Equal 

 weigiits of tabasheer and pure calcareous spar, both reduced to fine powder, 

 were irregularly mixed, and exposed in the platina crucible to a strong fire in a 

 forge for 20*"; but did not even concrete together, (f) When magnesia was 

 used, no fusion took place at the blow-pipe. (g) Equal parts of tabasiieer 

 whiting, and earth of alum precipitated by mild volatile alkali, were mixed in a 

 state of powder, and submitted in the platina crucible to a strong fire for 20™, 

 but were afterwards found unmelted. 



Examination of the other specimens. — N° 1. This parcel contained particles 

 of 3 kinds; some white, of a smooth texture, much resembling the foregoing 

 sort; others of the same appearance, but yellowish; and others greatly similar 

 to bits of dried mould. The white and yellowish pieces were so soft as to be 

 very easily rubbed to powder between the fingers. They had a disagreeable 

 taste, something like that of rhubarb. Put into water, the white bits scarcely 

 became at all transparent; but the yellow ones became so to a considerable 

 degree. The brown earth-like pieces were harder than the former, had little 

 taste, floated on water, and remained opaque. Exposed to the blow-pipe, they 

 all charred and became black ; the last variety even burned with a flame. When 

 the vegetable matter was consumed, the pieces remained white, and then had 

 exactly the appearance, and possessed all the properties, of the foregoing taba- 

 sheer from Hydrabad, and like it melted with soda into a transparent glass. 



N°2. Also consisted of bits of 3 sorts, (a) Some white, nearly opaque, (b) A 

 few small very transparent particles, showing, in an eminent degree, the blue 

 and yellow colour, by the different direction of light, (c) Coarse, brownish 

 pieces of a grained texture. These all had exactly the same taste, hardness, &c. 

 and showed the same effects at the blow-pipe, as N° 1. 27 gr. of this tabasheer 

 thrown into a red-hot crucible, burned with a yellowish white flame, lost 1.Q gr. 

 in weight, and became so similar to the Hydrabad kind as not to be distinguished 

 from it. Some of this tabasheer put into a crucible, not made very hot, emitted 

 a smell something like tobacco ashes, but not the kind of perfume discovered in 

 that from Hydrabad, § 4. (e). 



N"'!. All the pieces of this parcel were of one appearance, and a good deal re- 

 sembled, in their texture, the third variety of N" 2. Their colour was white ; 

 their hardness such as very difflcultly to be broken by pressure between the fin- 

 gers. In the mouth they immediately fell to a pulpy powder, and had no taste. 



