the Oxyd of Chrome, and the Chromic Acid. 9S 
likely to be of much benefit to fociety, is fometimes found, . 
after a certain period, to be applicable to many important 
purpofes in the arts and the fciences. 
_ The acid and the oxyd of this metal, however, may be 
of the greateit utility. The former, on account of the beauti- 
ful emerald green colour which it communicates, even to 
enamel, without undergoing any alteration in its fhade, will 
furnifh painters in enamel with the means of enriching their 
pictures, and of improving their art; and the fecond, by 
the beautiful cinnabar red colour which it affumes and pre~ 
ferves in its combination with mercury, the orange red 
eolour which it gives with lead, and the carmelite red which 
it communicates to filver, may become exceedingly valuable 
to painting in ail and in water colours. 
It will be no lefs ufeful in chemiftry, by furnifhing an 
excellent re-agent to deteét the {malleft quantities of mer- 
cury, filver, and lead, diffolved in acids, by the different 
colours it produces in them when its ation is affifted by an 
alkali. But in the fame manner as this acid ferves to dif- 
cover the preience of the above-mentioned metals; the 
Jatter, in their turn, may ferve to difcover the chromic acid, 
if it has been previoufly put in a condition to produce the 
effets before mentioned. ; 
‘If abundance of the chromic acid fhould one day be 
found in any other combination than that of lead; were it 
extracted by means of the carbonat of potafh, we might 
make the red lead artificially, and furnifh, in great plenty, 
an excellent orange red colour for painting, which is fold 
yery dear in Siberia, where it is employed for that purpofe 
with great effet. In this refpe&t great benefit might be 
derived from the red lead, which is diffeminated in fmall 
cryftals or lamin, in the fiffures of quartzy and free-ftone 
matrices *, where they are commonly found, by reducing 
them 
* As many of our readers may not be acquainted with the hiftory of this 
ged lead, we fhall give the following fhort account ‘ah it; The foifil known 
under 
