■[«] 



though when a folution of the caufKc vegetable alkali 

 was added, each drop occafioned a white cloud. 

 Some drops of oil of vitriol, let fall on fome of this 

 fait, occafioned no effervefcence, nor raifed any fumes ; 

 and when fome of it was put on a red hot poker, it 

 rofe into blifters, and did not crackle. From all 

 which I conclude, that this was a true Glauber 

 fait. 



After this fait was feparated, the remaining liquor 

 was left in the tea-cup, and, at the end of four days, 

 it concreted into a yellow cake, which ftill contained 

 a good deal of a fait ; it weighed gr. ix. fo that there 

 had been a great increafe of weight, from the water 

 the falts had taken up in their cryftaliifation. This 

 matter was extremely bitter, and had likewife a cool- 

 ing faline tafte. Some of it, put on a red-hot poker, 

 melted, and rofe into blifters; it emitted a little 

 fmoak, but did not flame; and it had fuch a very 

 flight fulphureous fmell, that it was doubtful whe- 

 ther it proceeded from the yellow matter or the ig- 

 nited iron ; it burnt to a black coal, which tafted 

 fomewhat faltiih. Some oil of vitriol dropt on fome 

 of this matter occafioned very little effervefcence, 

 but raifed a ftrong pungent acid fmell, which I at 

 firft imagined muft be that of fea fait; but, from 

 the few marks I have obferved of the exiftence of 

 this filt in a perfect ftate in thefe waters, I have 

 iince thought, that it might be that of a volatile vi- 

 triolic acid, which had been formed by the union of 

 fome of the acid of the Glauber fait, with a ful- 

 phureous or oily matter, and diflodged by the addi- 

 tion of a fixed acid of the fame kind, though perhaps 

 there may be a pittance of a calculareous marine fait 



in 



