CHEMISTRY. 293 



partial vacuum is produced in the tube and the mercury rises. The 

 liquid may also be obtained by a sudden compression and the solid by 

 a sudden expansion, producing sufficient cold. — (-7. Fhys., ix, 38G, Novem- 

 ber, 1880.) 



Maskelyne has examined two samples of material said to be crystal- 

 lized carbon or diamond sand. The first was sent him by Mactear of 

 Glasgow. On testing it he found {a) that it would not scratch either 

 sapphire or topaz; (h) the particles polarized light; and (c) were not com- 

 bustible, hence the samj)le was not diamond dust. Since evaporation 

 with hydrofluoric acid caused it to disappear, it was probably a silicate. 

 The second sample came from Hannay, also of Glasgow, and consisted 

 of small crystallized particles, which in luster, in lamellar structure 

 on the cleavage surfaces, and in refractive power, presented exactly 

 the appearance of fragments of a broken diamond. They were inert in 

 polarized light, they easily scored deep grooves in sapphire, and they 

 were combustible, burning away entirely on platinum foil. The angle 

 between the cleavage faces was 70° 29', that of the diamdnd being 7()o 

 ■ 31'.7. Ilannay has himself given an account of the production of these 

 diamonds, in a paper read before the lioyal Society by l*rofessor Stokes. 

 This result is an outcome of his remarkable research on the solubility 

 of solids in gases. lie observed that when a gas containing carbon and 

 hydrogen was heated under pressure in presence of certain metals, its hy- 

 drogen is taken by the metal, and its carbon is set free. If this evolution of 

 carbon takes place in presence of a stable compound containing nitrogen 

 at a red heat and under a very high pressure, the carbon is obtained in 

 the clear transparent form of the diamond. The specific gravity of the 

 crystals is 3.5, and they yield on combustion 07.85 i)er cent, of carbon. 

 An iron tube 4 inches in diameter and half an inch bore was exhibited 

 as one of the tubes used in the experiment. These tubes burst in nine 

 cases out oi tew.— {Nature, xxl, 203, 200, 40-1, 421, 420, lS79-'80.) 



Cooke has made additional experiments in support of his early result 

 which fixed the atomic weight of antimony at 120.00 ; a result obtained 

 as a mean of fifteen analyses of five difiV'ieut preparations of antimony 

 bromide. In the present paper he discusses the causes of error to which 

 his previous method was liable, and concludes that they arise from the 

 analytical process, and not from a want of purity of material ; and fur- 

 ther that they are to a great extent under control. He then details the 

 results of experiments made with the volumetric method, by precipitat- 

 ing a known weight of antimonous bromide by a standard solution of 

 pure silver. As a mean of five analyses, the percentage of bromine 

 found was GG.GG51, against GG.CGG5 given by the fifteen previous anal- 

 yses, corresponding to an atomic weight of 120.01. The silver bromide 

 formed in the last two experiments, on drying and weighing, gave two ad- 

 ditional determinations— 120.01 and 120.00.— (Aw*. J. ScL, III, xix, 382, 

 May, 1880.) 

 Humpidge has given an excellent resume of the progress of discovery 



