602 Scientific Intelligence. 



graphite moulds in such a manner that the metal solidified from 

 the bottom upward. Kahlbaum, Roth and Siedler had found the 



(20°\ 

 D-^sJ of lead distilled in a vacuum to be 11-3415, and 



after subjecting it to a pressure of 10,000 atmospheres, 11-3470. 

 Soddy's ordinary lead gave 11-3465 as the average of 3 determina- 

 tions agreeing within 8 units in the last place, while bis thorite 

 lead gave 11*376. If the atomic volumes of isotropic elements are 

 identical so that the densities are proportional to the atomic 

 weights, then taking ordinary lead as 207*10, the thorite lead 

 would have the atomic weight 207*64. During the purification 

 of this lead bismuth was specially looked for, but if any at all 

 was present its quantity was less than one part in 10 millions of 

 the mineral, so that it would appear that bismuth is not one of the 

 products of the thorium disintegration. It is an interesting fact 

 that a little iodine was present, and between 1 and 2 grams of 

 this element were extracted from the sample of thorite. A trace 

 of thallium was probably also present. — Nature, xciv, 615. 



h. l. w. 



3. The Analysis of Alloys containing Tin, Antimony and 

 Arsenic. — F. A. Stief has devised for this analysis a rapid 

 method which, although not new in general principles, is original 

 in some of its important details and may be carried out upon a 

 single sample without filtration. Only an outline of the process 

 can be given here, and the original article should be consulted 

 by anyone using the method. The alloy is dissolved in hot con- 

 centrated sulphuric acid, a proper amount of hydrochloric acid is 

 added and arsenious chloride is distilled off and determined 

 volumetrically by iodine in bicarbonate solution. In the residue, 

 after proper dilution with water, antimony is titrated with per- 

 manganate. The liquid then receives a suitable treatment with 

 more acid and iron wire, and the tin is finally determined by 

 means of iodine solution. — Jour. Indust. and Engr. Chem., vii, 

 211. h. l. w. 



4. Density and Dispersion of Liquid Hydrogen and Nitro- 

 gen. — It .has been shown theoretically by O. Wiener that the 



-r -r r , n * — 11 i 



Lorenz-Lorentz formula, — . — = const., may be written 



n -)- l a 



constant, where e and e denote respec- 

 tively the dielectric constants of the same substance in the gaseous 

 and liquid states. The corresponding densities are symbolized by 

 d and d '. u is called the "form-number" by Wiener. When 

 u = 2 the molecules of the substance in question are strictly 

 spherical in form, and when u is greater than 2 the excess affords 

 a measure of the departure of the molecules from the spherical 

 shape. The special conditions hypothecated in Wiener's theo- 

 retical considerations are best fulfilled at low temperatures, 

 hence liquid hydrogen and nitrogen afford good tests of the theory. 



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