140 Scientific Intelligence. 



8. Ratio between the Electrostatic and Electromagnetic units. — 

 M. D. Hurmuzesca in his measures employed Maxwell's method 

 in which an electrostatic attraction is balanced by an electro- 

 dynamic repulsion. The difference of potential at the ends of a 

 resistance, R, was measured by an absolute electrometer, and the 

 current through this resistance by an electro-dynamometer, the 

 movable coil of which was attached to the lever which carried the 

 movable portion of the electrometer. The value obtained was 

 V=3-0005 X 10 10 and V = 3-0020x 10 10 . The author believes that 

 the measurements of the electrical dimensions are correct to one 

 part in three thousand, and that the accuracy in the determina- 

 tion of V is controlled by that of the determination of the ohm. 

 — Comptes Pendus, Dec. 2, 1895. j. t. 



9. Discharges of Electricity through Gases. — If the discharge 

 tube is surrounded by water, alcohol, turpentine and other media 

 the discharge no longer takes place. This effect is not due to 

 conduction. If a point electrified by a Holtz machine is moved 

 near the tube the discharge is facilitated, and the discharges 

 take place under atmospheric pressure. — Ann. der Physik und 

 Chemie, No. 12, 1895, pp. 700-716. j. t. 



10. Double Refraction of Electric Waves. — R. Mack proves 

 that the electric rays through wood undergo double refraction, 

 and that these rays travel with different velocities. The values 

 obtained for the indices of refraction were Nj = l*75 and N 2 = 

 2*15. — Ann. der Physik und Chemie, No. 12, 1895, pp. 717-732. 



J. T. 



11. Relation between the atom and the charge of Electricity 

 carried by it. — Prof. J. J. Thomson, in the course of an import- 

 ant paper, illustrates the phenomena in the electric field in which 

 the movement of the atoms take place by various mechanical and 

 hydrodynamical analogies. In the course of his investigation he 

 employed the transformer of Elihu Thomson, which consists of a 

 species of secondary Ruhmkorf coil, the primary of which is con- 

 nected in circuit with Leyden jars, the spark of which is blown 

 out. The blowing out apparatus serves, so to speak, as the break 

 for the secondary of few turns wound on this primary. In this 

 way intense electromotive force can be obtained. The author 

 discusses the question of the relative velocities of the negative 

 and positive atoms, and shows that if the negative atoms move 

 more quickly than the positive, then in a discharge tube in a 

 steady state, the pressure at the positive electrode must be 

 higher than that at the negative. In the case, for instance, of a 

 tube l mm in diameter, 10 cm in length, filled with hydrogen at a 

 pressure of one ten-thousandth of an atmosphere, and conveying 

 a current of one ten-thousandth of an ampere, supposing the 

 velocity of the negative atom to be much greater than that of the 

 positive, the pressure at the positive electrode would exceed that 

 at the negative electrode by about twenty per cent. — Phil. Mag.> 

 Dec. 1895, pp. 511-544. J. T. 



