504 Mr. J. Denham Smith on the Subsalts of Copper. 



different hyd rated conditions in which the basic salts exist. 

 From these causes may be deduced the possible existence of 

 a very extensive series of basic sulphates varying considerably 

 in type, and subject only to the one restriction, that in all their 

 different conditions the sum of the equivalents of water and 

 metallic oxide shall always be equal to the sum of the same 

 constituents in some one of the forms in which the neutral 

 salt may crystallize." To show how far the "one restriction" 

 of this law holds good with the subsulphates of copper, we 

 find that the blue and the green crystallized neutral sulphates 

 of copper contain respectively 1 equivalent base and 5 water 

 = 6 equivalents of water and metallic oxide to one of acid, and 

 I equivalent of oxide and 1 equivalent of water equal to 2 

 equivalents to one of acid, whilst the subsulphates contain 

 respectively five, seven, eight, nine, and eleven equivalents of 

 oxide and water together, combined with one of acid ; thus 

 in no one instance do the subsulphates of copper agree with 

 the law laid down by Dr. Kane for regulating the constitution 

 of basic sulphates. True it is that Berzelius assigns the com- 

 position S0 3 3CuO, 3HO equal to 6 equivalents of water, 

 and metallic oxide to one of acid ; but, as has been before 

 stated, I believe one of these equivalents of water to be hygro- 

 metric, and that its true constitution is SO s 3 CuO, 2 HO. 



Being thus compelled to differ from those distinguished 

 chemists who have preceded me in these inquiries into the 

 constitution of subsalts and of the subsulphates of copper, I 

 would submit the following idea of the constitution of this 

 class of salts, at the same time distinctly refusing to draw any 

 general conclusion from a rule which I only know is in ac- 

 cordance with observations upon one particular class of salts. 

 I consider the subsulphates of copper to exist as anhydrous 

 sulphate of copper combined with two or more equivalents of 

 hydrated oxide of copper; these compounds, in most in- 

 stances, unite with definite proportions of water, precisely in 

 the same manner as some neutral and acid salts combine with 

 water of crystallization, which like them they part with at 

 stated elevations of temperature. 



This view is completely borne out by the subjoined ta- 

 bular arrangement of all the subsulphates of copper I have 

 been able to procure. Could I consent to consider either 

 the water or the oxide of copper as standing in the same re- 

 lation to the other as an acid does to its base, Mr. Graham's 

 theory of the constant neutrality of salts, as applying in this 

 instance, might readily be admitted ; but believing both of them 

 to be only capable of acting as basic oxides, I am compelled 

 to reject it, and admit the existence of basic as I do of acid salts. 



