498 Scientific Intelligence. 



with water lowering it to 32*38 per cent. In consequence the 

 author first attempted to prepare boron electrolytically. When 

 a current of 35 amperes is passed through boric oxide mixed with 

 one fifth of its mass of sodium borate and heated to 1200°, boron 

 is set free but at once burns to oxide. He then tried reduction by 

 means of magnesium, mixing 70 grams of finely powdered mag- 

 nesium with 210 grams of recently fused boric oxide, and heating 

 the mixture to bright redness in a clay crucible. After the action 

 was over, the mass was treated with water acidulated with hydro- 

 chloric acid, then with boiling strong hydrochloric acid, then with 

 alcoholic potash and finally with hydrofluoric acid. The product 

 was a light maroon powder, containing 94 or 95 per cent of 

 boron. If this be fused with 50 times its weight of boric oxide 

 and again treated with magnesium a product is obtained contain- 

 ing 98*3 percent of boron. And if the leduction be effected in a 

 crucible brasqued with titanic oxide and carbon, the percentage 

 of boron may reach 99*2. — O. it., cxiv, 319, 392; J. Chem. Soc, 

 lxii, 681, 682, June, 1892. g. r. b. 



4. On the Atomic Mass of Boron. — Abrahatx has determined 

 in Dixon's laboratory the atomic mass of boron by titrating boron 

 bromide by means of silver nitrate. The mean of five accordant 

 determinations gave 10-825. — J. Chem. Soc, lxi, 650, Aug., 1892. 



G. F. B. 



5. Absorption power of metals for the Energy of Electrical 

 waves. — Hertz concluded from his experiments that the production 

 of resonance and the period of oscillation in resonators are not 

 affected by the specific resistance or the magnetic properties of the 

 secondary conductor. Bjerknes of the University of Christiana 

 has examined this subject using au electrometer and finds that cop- 

 per, brass, german silver, platinum, nickel and iron show differ- 

 ent absorptive powers. The rate of absorption increases with the 

 resistance and the magnetization of the metal. Iron and nickel 

 showed a marked damping effect. Their magnetization however 

 could be reversed one hundred million times per second. Bjernkes 

 makes no l-eference to earlier papers of John Trowbridge and also 

 of Professor Thomson of Cambridge, England, on this subject. 

 Ann. der Physik und Chemie, 1892, No. 9, pp. 69-76. J. t. 



6. Electrical Oscillations. — M. Zehndee exhibits to a large 

 audience Hertz's oscillations by placing the conducting rods in 

 the focal line of a concave mirror. These rods are connected with 

 a Geissler tube within which the ends are placed very close to- 

 gether so that a general luminosity is produced inside the tube. 

 The effects are augmented by a species of relay. On either side 

 of the terminals of the resonator are two other terminals from a 

 circuit of 600 Plante cells of small size, which are regulated so 

 that the current is just able to pass between the terminals. When 

 the resonator responds to the electric oscillations the discharge 

 from the cells is augmented. It is also possible to work with 

 another Ruhmkorff coil instead of with the secondary battery. 

 Ann. der Physik und Chemie, 1892, No. 9, pp. 77-92. j. t. 



