1824.] Acetic Acid with Peroxide of Copper. 191 



Dr. Thomson calculated from Proust's experiments that the 

 neutral acetate of copper is composed of 39*41 of oxide of 

 copper, 25*12 of acetic acid, and 35*47 of water ; and he adds, 

 in his System, that he considers these to be the true consti- 

 tuents of the salt. More lately, Mr. Richard Phillips has re- 

 sumed the accurate investigation of these compounds. He 

 found the neutral salt composed of 39*2 oxide of copper, 49*2 

 acetic acid, and 11*6 water;* and its constitution, in his opi- 

 nion, is 1 atom of oxide of copper, 2 atoms of acetic acid, and 



3 atoms of water. In different experiments he obtained from 

 38*9 to to 39'5 per cent, of oxide of copper. To determine the 

 quantity of acetic acid, he decomposed the salt by hydrate of 

 lane. The uncombined lime remaining in the liquid was preci- 

 pitated by carbonic acid gas ; and after the excess of the latter 

 had been expelled by ebullition, the solution of acetate of lime 

 was decomposed by carbonate of potash, and the quantity of 

 acetic acid was estimated from that of the carbonate of lime. 

 He then examined verdigris, of which he had procured an 

 uncommonly pure specimen ; and an analysis, conducted in a 

 similar manner, indicated as its constituents 43*25 oxide of 

 copper, 28-3 acetic acid, and 28*45 water, which, in atoms, is 

 equivalent to 1 atom acid, 1 atom oxide of copper, and 6 atoms 

 water. When verdigris is decomposed by being treated with 

 water, Mr. Phillips found that neutral acetate of copper (which 

 he calls binacetate) passes into solution, and the green salt 

 which remains undissolved is, according to him, composed of 

 2 atoms of oxide of copper and 1 atom of acid, or, when anhy- 

 drous, of 0*7619 of oxide of copper and 0*2381 of acetic acid. 

 With respect to the black pulverulent substance into which this 

 salt is converted by the action of water, he has left undecided, 

 whether it consists of oxide of copper, or of a salt containing a 

 still greater excess of base. In all of these analyses by Mr. 

 Phillips, we are presented with deviations from the above- 

 mentioned empirical rule ; for, in the neutral salt, the oxygen 

 of the water is 1 J- time that of the oxide of copper, in verdi- 

 gris the oxygen of the acid is 1.1- time that of the oxide, and 

 in the sub-salt obtained by treating verdigris with water, the 

 oxygen of the base is to that of the acid in the proportion of 



4 to 3. 



1. Neutral Acetate of Copper. 



I have already stated that Mr. Phillips considers the water 

 of this salt to constitute 3 atoms for each atom of oxide of cop- 

 per. This proceeds, however, from his having adopted an 

 erroneous number for the atomic weight of acetic acid. By the 

 direct analysis which I have made both of this acid and of its 



. • Annuls, N. S. vol. i. ■>. 418. 



