1822.) Composition of Common Verdigris. 163 
eexperiment being repeated, using a. flask instead of the cru- 
cible, 43-3 parts were obtained, giving a mean of 43:25 of per- 
~oxide of copper. 
. According to Dr. Thomson’s latest experiments, the number 
representing hydrogen being 1, that of acetic acid is 50, and 
carbonate of lime being also 50, the quantity obtained in the 
experiments above detailed will indicate that of the acetic acid 
sin 100 parts of the blue crystals, or 233. per cent. which, 
being added to 43-25 of peroxide of copper, will give as) the 
composition of these crystals, 
PRC CUGACTO pte c's ly staan + ¢ a OL 
Peroxide of copper... . se eee 45°25 leaving for 
go a erie MIR, 28°45 
100-00 
Now an atom of acetic acid being 50, that:of peroxide of 
copper 80, and of water 9, it will appear that these blue crystals 
of acetate of copper are by theory composed of 
In 100 parts, 
Watomrof'acetic'acid .....20.502. SO Poi ar 
1 atom of peroxide of copper...... BO iene ee Oe 
GeatemsyOl Wael. fay saciiseeneere ® ET eae Ea 
184 100-00 
Ihave already observed that these crystals are readily decom- 
posed by water, and its effects upon the salt are sufliciently 
-marked to merit particular notice; a small quantity of water 
being added to 100 grains of the crystals, the whole became 
a pulpy mass. When the water was increased,to a pint, a 
blue solution was obtained, and a greenish precipitate thrown 
down. Upon examining this blue solution, it was found to 
consist of binacetate of copper, and the green precipitate of sub- 
acetate, composed of one atom of acid and two atoms of oxide. 
‘It is, therefore, evident, that in addition to the acetate and bin- 
acetate of copper already described, there exists a subacetate 
composed of 
One atom of acetic.acid . ..........4. 50 
Two atoms of peroxide of copper 80 x 2 160 
210 
When this subacetate was diluted with a further quantity of 
water, it became, as I have already noticed, quite brown in a 
few days; but whether it was totally decomposed into per- 
oxide, or was another subsalt, | have not:examined. 
Having now ascertained that a compound of one atom of 
acetic.acid and oxide of copper actually existed, I proceeded to 
M 2 
