1824.] Acetic Acid with Peroxide of Copper, 201 



composed of an atom of sulphate of lead and an atom of hydrated 



peroxide of copper (C Aq* + Pb '&). Is it not equally possible 

 [hat hydrated peroxide of copper may combine, under favourab e 

 circumstancesfwith acetate of copper? It may be .objected £■* 

 the Quantity of water is greater than is required to form a 

 MIS such also is the constitution of 4e ^mbinaUon. 

 oxide of zinc and of magnesia already alluded to, and it is 

 surely not assuming too much to admit an excess of water 

 which is only double* the water of crystallization contained by the 

 Two compounds when separate. On this supposition, ^for- 

 mula for the constitution of verdigris would be Cu A* + Cu Aq' 2 , 

 * a n f P„ A j- fi Aa * We may add, that if the constitu- 

 Sff of v rdigrts tl^oneJyr^L^i by the latter simple 

 formula i would be difficult to expeet so remarkable a mobility 

 ™" ii constituents, that the weakest chemical force d,s- 

 uuSen, and causes ihem to combine in ditt'erent proportions 



4. Black Sub-acetate of Copper. 

 When the soluble sub-salt is heated in a dilute solution, it 

 deposits a flocky liver-brown coloured substance, which when 

 received upon /filter, washed, and dried, appears black and 

 soiNstronoly every thing with which it comes in contact. This 

 uttanc^Isses Ldilf through ***".* %£*% * 

 water turbid whenever we begin to wash it. If it be washed so 

 Ton 'as the water continues to dissolve out any copper, and if 

 tKteed liquid be evaporated to dryness, there is left upon 

 the e ass a thin, transparent, colourless film, resembling .a coat- 

 [„g ff varnish. This proceeds from the brown salt, which had 



^H^tep^d"^ verdigris or the insoluble subsalt 



in wa ter, L mtereddiquid if more easily obtained ~ent , 



• but in this case, a portion of the insoluble green salt always 



escapes decompo'sition, and remains, therefore, intermixed with 



th lK3s1f this black subsalt dried in a temperature of IMP 

 on being analyzed by hydrate of barytes, and by precipitat n^. 

 the copper with a plate of iron, yielded from 5-6 to o 7 paits ot 

 u pbateofbarytes! and from 91-6 to 9*5 MrtJ; of P^eo 

 copper In another experiment, in which the salt vas decom 

 3d with sulphuric acid, I obtained 183-9a parts o Bulphate of 

 cooper --= 91-46 peroxide of copper. The mean ot these analy- 

 sed mdicates 92 percent, of peroxide of copper, whose oxygen 



I think 



was too inconsiderable for purposes of an analytical examination. 



