( ) 
t put a piece of red Copper cn a Coppcl into the 
Focus of the Ciafs: it melted, and fent forth fome thin 
Fumes 5 and after it had been fome time in fuiion, it turn’d 
liquid like an Oil. I withdrew this melted matter, and 
as it grew cold, it fix’d into a Regulus of a reddifh 
brown colour, whkh was hard, brittle, and not du^ile 
under the Hammer- If one breaks it, it turns into a red 
Powder like Cinabar of Antimony 5 and when view’d 
with a Microfcope, appears fo many little, red, tranfpa-' 
rent Grains like fmall Rubies; in fo much that one would 
readily take this Regulus to be a deep* colour’d red 
Glafs. 
I endeavoured to make this vitrified Copper fpread 
abroad in melting, by mixing it with common white 
Glafs for which end I powder’d fome of this vitrifi- 
ed Copper and common Glafs, and mixing them melted 
them together 5 but the Mixture when in fudon took at 
firft a beautiful green Colour, and continuing it longer 
in the Focus, it turn’d blewifh. I believe we may attri- 
bute this change of Colour to the Alcali Salts of the 
Glafs ading on the Particles of Copper 3 for thofe Salts 
ufually draw a green or blewifh Tinduie from this Me- 
, tab • 
To preferve therefore this red Colour of the vitrified 
Copper, when mix’d with common Glafs, I made ufe of 
this Expedient. - I melted in the Focus upon a Coppel a 
piece of Copper, and as foon as it began to vitrify I caft 
upon it fome common Glafs 3 as foon as the Glafs was 
melted I took them together out of the Focus without 
confufing them 5 and as foon as they were cold, feparated 
the Regulus from the Glafs as well as poffible; and pick'd 
out of it fome pieces of the Glafs, loaded with fora© 
very fmall red tranfparent Particles of the Regulus. 
Jim 
