172 Scientific Intelligence. 



Moreover, in distilling an alloy of gold and tin, when the mixed 

 vapors come in contact with air the tin is oxidized and the gold 

 condenses in the finely divided condition corresponding to the 

 "purple of Cassius." Similar purple products are formed also 

 with other oxides, such as silica, zirconia, lime, magnesia, and 

 alumina. — Oomptes Rendus, cxli, 977. h. l. w. 



5. Fluoride of Bromine. — Although Moissan had noticed that 

 fluorine reacts with bromine very vigorously, the product of the 

 reaction was not isolated by him. Lebeau has now prepared the 

 compound and has found that it is a colorless, fuming liquid cor- 

 responding to the formula BrF 3 . Its vapor is very irritating, 

 attacking the skin violently. It solidifies at about 4° to a color- 

 less, crystalline solid. The compound possesses great chemical 

 activity, reacting violently with water, and attacking many other 

 substances similarly to free fluorine. — Comptes Rendus, cxli, 

 1018. h. l. w. 



6. On some Properties of the a-Rays from Radium. — Prof. E. 

 Rtjtheefued th us summarizes his recent investigation of this 

 subject. 



(1) The rays from radium in radio-active equilibrium are com- 

 plex, and consist of a particles projected with different velocities. 



(2) The a particles decrease in velocity in passing through air 

 and through aluminium. 



(3) The absence of increased deflection of the rays from a 

 thick layer of radium, after passing through aluminium, observed 

 by M. Becquerel, is a necessary consequence of the complexity of 

 the rays. 



(4) The decreasing path of the rays in air, observed by Bec- 

 querel, is also a necessary consequence of the complexity of the 

 rays. 



(5) There is evidence of a distinct scattering of the rays from 

 radium C in their passage through air. — Phil. Mag., Jan. 1906, 

 pp. 166-176. j. t. 



7. Emission Spectrum of the Auer burner. — H. Rubens has 

 measured the amount of energy given out by the so-called Degeas 

 mantle which is composed of 99 - 2 per cent thorium oxide (Th0 2 ) 

 and 0-8 per cent cerium oxide (Ce 3 3 ). The method of measure- 

 ment was substantially that described in Wied. Ann., lx, p. 737, 

 1897. The measurements were taken between wave lengths 

 a = 0, 45//, and a ± 18/x. Curves of energy are given for the 

 Auer burner in question, for the ordinary Bunsen burner and with 

 a mantle covered with a thin layer of iron oxide. One obtains 

 the latter by dipping the Auer burner in ink and then raising to a 

 glow in the Bunsen burner. The mantel shows then in the flame 

 mantel of the burner a red glow. The curves show that the 

 mantel of the Auer burner is transparent for the rays of the Bun- 

 sen burner. They also show that the Auer burner radiations 

 depart largely from the maxima of the Bunsen burner. Rubens 

 believes that the cerium oxide plays a role in the burner similar 

 to that of a sensitizer on the photographic plate in that it brings 



