4296 Ona saline Substance from Mount Vesuvius. 
was at that time called vitriolated tartar, and it was in 
consequence mentioned as such in an Italian publication 
soon after. But as this denomination, surprising at that 
period, was not supported by the relation of any experi- 
ments, or the citation of any authority, no attention was 
paid to it; and the existence of this species of salt, native 
in the earth, has not been admitted by mineralogists, no 
mention being made of it, I believe, in any mineralogical 
work published since. 
b. 1 was informed by letter, that it had *¢ flowed out 
Jiquid from a small aperture in the cone of Vesuvius,” and 
which J apprehend to have happened in 1792 or 1793. 
c. The masses of this salt are perfectly irregular, their 
texture compact, their colour a clouded mixture of white, 
of the green of copper, and of a rusty yellow, and in some 
places are specks and streaks of black. 
d. A fragment melted on the charcoal at the blow-pipe 
formed hepar sulpburis. 
e. A piece weighing 9°5 grains was so strongly heated 
in a platina crucible, that it melted and flowed level over 
the bottom of it, but did not lose the least weight. 
Ff. Not the slightest fume could be perceived on holding 
a glass tube wetted with marine acid over some of this salt, 
while triturating in a mortar with liquid potash; but a 
similar mixture being made in a bottle, and which was 
immediately closed with a cork, to which was fixed a bit of 
reddened litmus paper, the blue colour of the paper wag 
restored, . 
g. Being dissolved in water, there was a small sandy resi- 
due, which consisted of green particles of a cupreous na- 
ture, of a yellow ochraceous powder, and of minute crystals 
of a metallic aspect of red oxide of iron, by which the 
black spots in the mass had been occasioned*. Mr, 
Klaproth found a similar admixture in muriate of soda from 
Vesuvius f. 
h. The solution had a feeble green tint. It did not alter 
blue or reddened turnsol paper. 
i. Prussiate of soda and iron threw down a small quan- 
tity of red prussiate of copper from it. Liver of sulphur 
and tincture of galls likewise caused very small precipita- 
tions. 
* What mineralogists denominate speculary iron ore, Fer oligiste of Mr. 
Haity, appears to be merely red oxide of iron in crystals; red hematite the 
game substance in the state of stalactite; and red ochres the same in a pul- 
verulent form, ‘The hematites which afford a yellow powder are hydrates 
ef iron, + Essays, vol, ii. p. 67, Eng. Trans. 
je Car =] 
eee oA 
