Chemistry and Physics. 59 



showing only numerical differences in the values obtained, and 

 proving, for instance, for the air, that its deviations from Mariotte's 

 law are even less than appeared before. But the most important 

 results of the researches is that the divergences from Mariotte's 

 law shown by the air being negative at pressure above the mean 

 atmosphere, as was observed by Regnault, proved to be positive 

 (decrease of volume slower than the increase of pressure) at pres- 

 sures below it. We must then conclude that the air experiences 

 a change of compressibility at a certain pressure above the mean 

 of that of the atmosphere; and this conclusion is supported by the 

 circumstance that such a change was noticed also in the carbonic 

 and sulphurous acid gases, but at pressures far lower than is the 

 case for air. Only for hydrogen the divergence is of the positive 

 kind at all pressures. Alto-ether we must conclude that the de- 

 viations from Mariotte's law are far more complicated than has 

 been suspected. — Nature, xv, 70. e. c. p. 



9. Physical Properties of (rallimii.—'M. Lecoq de Boisbap- 

 drajj has iv. ,, gram of pure gallium. 

 In the liquid state this metal is of a beautiful silvery whiteness; 

 but in crystallizing it assumes a very pronounced bluish tinge, 

 and its luster notably diminishes. Isolated crystals may be ob- 

 tained which are based octahedra. The melting point was found 

 to be 30°-15, which was unaltered after remaining for two hours 

 in boiling water. It was therefore eertainlv free from potassium. 

 It was next kept for half an hour in nitric acid diluted with its 

 volume of water. The loss amount m of a mil- 

 ligram, and the point of fusion remained unaltered. The calcu- 

 lation of M. Mendeleeff for a hypothetic substance which seems 

 to correspond tst in several of its properties, con- 

 ducted to the number 5-9. The first measurement with 6 centi- 

 grams gave a density of 4-7 at 15°. Later observations gave 

 the higher results of 5-5 to 6-2. Finally, a measurement with 58 

 centigrams gave, in two experiments, 5"90 and 5-97. The same 

 gallium was afterward- home between 60° and 

 70° in nitric - ■. olume of water, v. ashed, pretty 

 strongly, heated, ami. air. Its density at 

 24°-45 was then 5-956.— Comptes Bendus, lxxxiii, 61 1, Phil. Mag., 

 ii, 398. e. c. p. 



10. Plasticity of Ice.— Prof. Bianconi, of Bologna, in 1871, 

 published some experiments on the bending and torsion of bars 

 and planks of ice (Mem. Acad, of Bol«y»o. 3d ser., vol. i.) These 

 show that ice may undergo slow about any 

 crushing or regelation, and that n ittleness it 

 possesses a slight degree of plasticity. Now Prof. Bianconi gives 

 the results of further experiments on ice, much like those of Heim, 

 or, yet more, those of Mr. Tree - "f metals. 

 Granite pebl BW slowly pressed into ice at the 

 " — e temperatures, and not only do they penetrate into it as they 



