192 M. BerzeUus on the Combinations of [Sept. 



combinations with different bases, 1 think I have determined 

 with considerable certainty, that it contains CM7 of its weight 

 of oxygen, and that it forms neutral salts with a quantity of a 

 base, whose oxygen is one third of that contained by the acid, 

 that is y = 15*066. Phillips found in the neutral acetate as 

 much as 39*5 per cent, of oxide of copper, for whose saturation 

 there would be required 51-17 of acetic acid ; the deficit, which 

 must be viewed as water, is 9*33, which corresponds, as nearly 

 as can be expected, with the supposition that the oxygen of 

 the oxide of copper and of the water of crystallization is the 

 same, that is, that the salt contains only two atoms of water. 

 Were the oxygen of the water 1 \ time that of the oxide of 

 copper, according to Phillips's calculation, the composition of 

 the salt would be materially different, as will be rendered 

 evident by the following comparison : 



With 2 atoms of water. With 3 atoms of water. 



Multiples of oxy. Mult, of oxy. 



Peroxide of copper 39-76 ... 1 38-05 ... 1 



Acetic acid 51-22 ... 3 49-00 ... 3 



Water 9-02 ... 1 12-95 . . . li- 



The quantity of oxide of copper alone indicates decidedly 

 to which of these two calculations our salt ought to be referred. 

 In order, however, that I might not depend entirely upon pre- 

 ceding experiments, according to which the composition of this 

 salt has been calculated in the tables (although there was no 

 reason for doubting their accuracy), I made a new experiment 

 with a view to determine with certainty the quantity of oxide 

 of copper; and I employed for this purpose crystals of a salt 

 which had never been dried otherwise then by long keeping : 

 100 parts of this salt were dissolved in dilute sulphuric acid ; 

 and after evaporation to dryness, the excess of sulphuric acid 

 was expelled, by ignition over the flame of a spirit lamp. The 

 sulphate of copper, which was in the state of small white crys- 

 talline grains, weighed 79 parts ; and on being again exposed 

 to a moderate red heat, it sustained no additional loss of 

 weight. 79 parts of sulphate of copper are equivalent to 39-29 

 parts of oxide of copper ; if we now abstract the water of 

 decrepitation, which the crystals of this salt sometimes contain 

 in considerable quantity, my result will be found to coincide 

 still more closely with calculation. The formula and compo- 

 sition which I have given in my Chemical Tables for the acetas 

 cupricus c. aqua, are therefore accurate. 



2. The Subacet cites obtained by treating Verdigris with Water. 



Verdigris, when put into water, swells up, and is converted 

 into a doughy mass, composed of minute crystalline scales. 

 The filtered liquid, when in a state of- concentration, has an 



