428 Onasaline Substance from Mount Vesuvius. 
ductions of the Lipari islands, and suggested that it might 
be a more general product of volcanoes than had been su- 
spected *, it became important to ascertain whether the 
presence of any in this salt proved Vesuvius likewise to 
be a source of this acid. Alcohol heated on a portion of it 
in fine powder, and then burned on it, did not however 
show the least green hue in its flame. 
s. To ascertain the proportions of the ingredients of this 
saline substance, the following experiments were made: 
Ten grains of sulphate of potash of the shops were dis- 
solved in 200 grains of water, and an excess of muriate of 
platina added. The precipitate edulcorated with 100 grains 
of water, and dried on a water bath, weighed 24°1 grains. 
Ten grains of the saline part of the native salt, treated 
precisely in every respect in the same way, afforded 17:2 
grains of precipitated muriate of platina and potash. 
If 24:1 grains of this precipitate correspond to 10 grains 
of sulphate of potash, 17°2 grains of it correspond to 714 
grains of this salt. 
It has been seen (7) that 10 grains of the saline part of 
this volcanic salt would have afforded 12°55 grains of sul- 
phate of barytes. 
But 7°14 grains of sulphate of potash form only 9°42 
rains of sulphate of barytes}, and therefore the remaining 
3°13 grains of sulphate of barytes would be produced by 
the sulphate of soda, and correspond to 1°86 grain of it in 
an arid state, or uncombined with ice ft. ' 
Ten grains of the saline part of this native aalt would 
have produced 1°12 grain of ignited muriate of silver (4). 
By accurate experiments 241 grains of ignited muriate of 
silver have been found to correspond to 100 grains of ig- 
nited muriate of soda §. 
Consequently the soluble portion of the present Vesuvian 
galt consists of 
Sulphate of potash ,...eesee08. 7°14 
Sulphate of soda ......e0+see00 1°86 
Muriate of soda......seeesesee 0°46 
Muriate of ammonia 
Muriate of copper. ‘| cecerecee O54 
Muriate of iron.... 
i 
10°00 
t. Theinsoluble sandy residue (g) having been thoroughly 
* Trans. of the Geolog. Soc. + Dr. Marcet on Dropsical Fluids, 
} Prof. Klaproth’s Essays, vol. i. p, 282, 
§ Dr. Henry, Phil. Trans, 1810, 
edulcorated, 
