Intelligence and Miscellaneous Articles. 395 



ON A NEW SPECIES Of ACETATE OF COPPER. 



M. F. Wohler lias found that the neutral acetate of copper will com- 

 bine with another proportion of water than that which is contained 

 in the common crystallized verdigris. This new salt is interesting 

 in many respects : it forms large, beautiful, transparent crystals, of 

 the same shade of blue as sulphate of copper, which at once serves 

 to show that a difference exists between it and the common neutral 

 acetate. When a crystal of this salt is heated to about 90° Fahr. 

 it soon becomes opake and green like verdigris, without changing 

 its exterior form, but by slight pressure is converted into a mass 

 of small crystals of verdigris. This transformation is immedi- 

 ately perceived by throwing a crystal into warm \vater, and the 

 slower a crystal is heated the larger and more distinct are the small 

 crystals of verdigris into which it is changed. This phjenomenon 

 exactly resembles the known changes of form .vhich take place with- 

 out change of composition, which have been observed in sulphate of 

 magnesia, sulphate of zinc, &c., and it is for this reason that this salt 

 of copper deserves attention ; for it shows that in phenomena of this 

 kind we ought to be careful to distinguish between those cases in which 

 change of form occurs without change of composition, and those 

 in which the one is the cause of the other. The preceding phaenome- 

 non belongs to the latter class ; for the change of colour and form is 

 connected with the separation of four fifths of the water of crystalli- 

 zation of this salt. This latter modification does not occur when 

 the crystal remains entire and is become pseudomorphous, for the 

 disengaged water remains inclosed between the new formation of 

 small crystals ; and for the same reason, immediate analysis would 

 show the same proportion of water to exist in it, as in the modified 

 crystal. This circumstance might easily be overlooked, for when a 

 crystal changed to green is exposed to the air, it gradually parts 

 with the interposed water j this quantity of water, although in itself 

 small, may be detected by pressing one of the transformed crystals 

 between blotting-paper, which will become damp, from the interposed 

 water retained between the new formation of the small crystals of 

 common verdigris. The quantity of water which the blue salt loses 

 by its conversion into the green is 26'48 per cent. ; this is four times 

 as much as that which is still retained by the resulting green salt, 

 that is, the common crystallized verdigris. Thus the blue salt con- 

 tains 33' 1 1 per cent., or 5 equivalents of water ; it is very easily pre- 

 pared by dissolving verdigris in warm, but not boiling, water acidu- 

 lated with acetic acid, and crystallizing the solution. — Journ. de Phar- 

 macie, July 183t). 



FACTS IlELATIVE TO THE HISTORY OF ^THER. 



Some time ago M. Liehig was led, from the results of an analysis 

 of phosphovinate of barytes,to consider the acid of this salt as a com- 

 bination of phosphoric acid and aether. A similar composition would 

 naturally be assigned to the sulphovinates, but the experiments which 

 were made to verify this supposition served only to show that by the 

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