[ 33 ] 
tho’ the- polifli of the marble was quite effaced, yet 
there was not the leaft difcharge of any of the co- 
lours, nor were they any-wife dulled, &c. 
N°. 6. A deep crimfon-red colour, being left 
twenty hours in a ftrong lye of common foft green 
foap, buffered no change ; and boiled in the fame 
lye half an hour, alfo buffered no change. Tire 
marble finely powdered, and aqua fortis effufed over 
it, the marble particles were nigh deft roved ; but 
feveral red particles (no doubt the colour) remained. 
The marble, by common calcination, i. e. in a com- 
mon coal fire, for half an hour, is intirely difeharged 
of its colour. We made the experiments on four 
other reds, and the refult was much the fame as 
abovefaid ; fo that this is a ftandard for his reds. 
. N°. 5. A deep fea-green, being left twenty hours, 
in a ftrong lye of common foft green foap, buffered 
no change ; but boiled in the fame lye it quite dif- 
eharged its green colour : however, it yet remained 
flightly tindured yellowifh. By common calcina- 
tion the colour was quite difeharged. Some other 
greens were tried, and anfwered much the fame. 
N°. 10. 15. & 16. Brownifh or terreftrial yellowifh 
colours, near to a clay colour, boiled in a ftrong lye 
of common foft green foap, they fuffered no change. 
By common calcination the colours were difeharged, 
but retained a greyifh caft. Thefe colours, covered 
for forty-eight hours with a layer of the laid common 
foap, fuffered no fenfible change. 
N°. 19. A bright yellow, boiled in a ftrong lye 
of common green foft foap, fuffered no change ; 
and covered with a layer of the fame foap for forty-- 
eight hours, the colour is dulled. By common cal- 
Vol. LI. F cination 
