a new Kina oj Rain. lii 
touching it again with the aforefaid liquors, it Chewed a (light 
effervefcence with the acids. When tried with the (yrup of vio- 
lets, this became a pale green ; fo that I was perfuaded it con- 
tained a calcareous hilt*. With the decoftion of galls no preci- 
pitation was produced. 
The matter being afterwards dried in the (hade, it appeared 
a very l'ubtile, fine earth, of a cretaceous colour, but inert, 
from having been diluted by the rain. 
I next thought of calcining it with a (low fire, and it affumed 
the colour of a brick. A portion of this being put into a cru- 
cible, I applied to it a ftronger heat, by which it loft almoft all 
its acquired colour. Again, I expofed a portion of this for a 
longer time to a very violent heat (from which a vitrification 
might be expe&ed) ; it remained however quite foft, and was 
eafily bruifed, but returned to its original dufky colour. 
From the mod accurate obfervations of the fmoke from the 
three calcinations, I could not difeover either colour or l'mell 
that indicated any arfenicalor fulphureous mixture. 
Having therefore calcined this matter in three portions, with 
three different degrees of fire, I prefented a good magnet to 
each ; it did not aft either on the firft or fecond ; a (light at- 
traction was vifible in many places on the third : this perfuaded 
me, that this earth contains a martial principle in a metallic 
form, and not in a vitriolic fubffance -f. 
The nature of thefe fubftances then being difeovered, their 
volcanic origin appears ; for iron, the more it is expofed to 
violent calcination, the more it is divided, by the lofs of its 
phlogiffic principle ; which cannot naturally happen but 
in the great chimney of a volcano. Calcareous fait, being a 
marine fait combined with a calcareous fubffance by meani 
* Ttied likewife with a folution of lead in the vegetable acid, it lofl: its natural 
Colourand its traniparenev, and became milky. I ftiould be inclined to believe this 
to be the effect: of the alkaline particles, and thus account for the efflorefcencc 
on the iron’s being expoied to the air. 
f Becaufe, otherwife the water would not have produced an effervefcence 
with the acids, but would have fhewn it with the alkalies ; and, in the triple cal- 
cination, the red colour would rather have been increafed than dumnilhed* 
Vol. LX XII. B of 
