141 
On the Manufacture of Verdigrise. 
The cement which the Swedes recommend for filling 
up the interstices between the squares, and of which I re- 
ceived a specimen of Mr. Cameron, was composed of 
linseed oil varnish, white lead and chalk, mixed together 
in such a manner as to approach to a fluid state, that it 
might more easily insinuate itself into the fissures. 
As the chief use of this invention is to cover and in- 
crust houses, I was desirous of trying my production by 
exposing it to the effects of the weather. I therefore nailed 
fragments of the Swedish stone paper, and of that made 
by myself, to a small board ; and having daubed over the 
joinings with cement, I exposed them in the month 
of August on the top of my house, and in the beginning 
of April the next year I found they had undergone no 
change. 
NO. 27. 
Observations on the Manufacture of the Jlcetite of Cop- 
per or Verdigrise , Verdet , 8 £c. By J A. Chap- 
tal.* 
THE acetite of copper is one of the preparations of 
that metal most frequently used in the arts. It is not 
only one of the principal resources of painting, hut upon 
many occasions is employed with great advantage in dye- 
ing. Almost all the oxydes of copper obtained by the ac- 
tion of saline substances have a blue colour, more or less 
inclining to green, and almost all the neutral salts cor- 
rode the metal, and produce that oxyde which is called 
verdigrise. It is sufficient to bring them into contact 
with the copper, or to immerse the metallic plates in a 
» Tillocbj voi 4, p, 71 From Annates ds Chimie , no. 75/ 
