472 Scientific Intelligence. 



tion of energy, one could compare the state of uranium to that 

 of a magnet. We can also compare the state of uranium to that 

 of phosphorescent bodies which seem to conserve their state of phos- 

 phorescence indefinitely. The photographic and phosphorescent 

 effect, however, of the uranium radiation indicates a consumption 

 of energ}^. This consumption is extremely feeble, and seems to 

 indicate that uranium can emit its unknown radiation for a long 

 period of years apparently without sensible diminution. — Comptes 

 Rendus, March 27, 1899, pp. 771-776. J. t. 



10. Source of Uranium Radiations. — Prof. W. Ceookes sug- 

 gests that uranium, thorium, polonium and radium have the power 

 of separating rapidly moving molecules from slowly moving ones 

 and appropriating a portion of the energy of the former. This 

 energy may be used in dissociation and maintaining radiations in 

 the ether. The air in the neighborhood of such substances would 

 be cooled. This cooling is so small as to escape detection, and 

 therefore the energy appears to be created out of nothing. The 

 author computes that air contained in a room 4x8x7m. could 

 supply one h.p. for fifteen hours. — Comptes Rendus y 128, pp. 

 176-178, 1899. j. t. 



11. Phosphorescence at low Temperatures. — A. and L. Ltjmieee 

 have found that the phosphorescence of calcium and zinc sulphides 

 produced by exposure to an arc light disappears wholly at about 

 — 50° C. When exposed to a magnesium light it disappeared 

 between — 70° and — 90°. When the exposure to a magnesium 

 light is made at — 191° C. the temperature of liquid air and the 

 body is heated, phosphorescence begins to appear at — 180° C. aud 

 increases with the heating. Rontgen rays act like ordinary light. — 

 Comptes Rendus, 129, pp. 549-552, 1899. J. T. 



12. Recueil Donnees numeriques publie par la Societe Franpaise 

 de Physique. Optique par H. Dufet. Deuxieme fascicule. Pro- 

 priety optiques des solides; pp. 417-785, Paris, 1899 (Gauthier- 

 Villars). — This volume contains tables of physical constants in 

 the department of optics, prepared under the direction of the 

 Physical Society of France. The opening tables give the refrac- 

 tive indices for different wave-lengths of certain remarkable sub- 

 stances, as calcite, quartz, fluorite, halite, and so on. Then 

 follows a table of refractive indices for certain important samples 

 of glass. After this we have an alphabetical list of inorganic 

 solids, largely mineral species, with their optical properties 

 arranged in tabular form ; references are given to the original 

 publication where the facts were given. This portion covers 

 pages 466 to 632. A like table for organic solids follows, and 

 then other tables giving the influence of temperature on optical 

 properties, and allied subjects, close the volume. This enumera- 

 tion of its contents will show how much this valuable book of 

 reference contains. 



