200 BoUey on the Molecular Properties of Zinc. 



Bolley gives, iu a paper "On the INIolecular properties of Zinc/' 

 a resume of less known observations on the physical properties 

 of that metal by other chemists, in addition to experiments of 

 his own. Zinc is generally stated to have a crystalline lamellar 

 structure, but the author had found that this was only the case 

 with zinc which had been heated to almost a red heat, and then 

 cooled ; while that which had been simply melted and then 

 cooled, had always a small granular structure. The diflPerences 

 in the observations on the spec. grav. of zinc are greater than in 

 any other metal ; they vary from 6"86 to 7"2. Bolley ascertained 

 by actual observation ou various specimens, that there existed 

 hollow spaces in the interior of the zinc, which were amply suf- 

 ficient to account for these variations. He cast small cylinders 

 of zinc about 10 grms. in weight, using every precaution to 

 prevent air being enclosed. These pieces were divided and sub- 

 divided, and the spec. grav. taken, in small pieces until well- 

 agreeing results were obtained. It was found, the smaller the 

 pieces, the higher was the specific gravity. He found that zinc 

 which had been heated to melting, and then quickly cooled, had 

 a specific gravity of 7*178, and when slowly cooled 7"145 ; that 

 which had been heated to redness and quickly cooled, of 7' 109, 

 and slowly cooled, 7"120. Zinc which had been simply melted 

 was comparatively malleable, while that which had been heated 

 to redness was not at all so. The ease with which commercial 

 zinc dissolves is ascribed to the presence in it of foreign metals. 

 But even in pure zinc there are diff"erences in the solubility, 

 which arise from the temperatures to which it has been heated. 

 Pure zinc was heated to melting, one part poured in cold water, 

 and another poured on a warm plate. Another specimen of the 

 same zinc was heated to redness, and cooled by the same method. 

 It was found that the latter was far moi-e easily dissolved in di- 

 lute acids than the former. He concludes that zinc melted at 

 as low a temperature as possible is distinguished by — 1. gra- 

 nular fracture ; 2. probable higher specific gravity ; 3. greater 

 malleability ; 4. less solubility in dilute acids ; while that melted 

 at a higher temperature has — 1. crystalline lamellar fracture; 

 2. probable less specific gravity ; 3. greater brittleness ; and 4. 

 far greater solubility in dilute acids. 



Bolley suggests that zinc is dimorphous. He finds a support 

 for this idea in the fact that the atomic volume of zinc is veiy 

 near that of platinum, iridium and palladium, three metals 

 which are dimorphous. 



In the October Number of the same Journal Schlossberger 

 has two papers on Physiological Chemistry. An investigation of 

 the uterine milk of the Ruminantia showed him that it contains 



