Chemistry and Physics. 81 



p. 629) and a complete account is given of the method of measur- 

 ing the resistances of the films. The conclusions are as follows : 



(1) The specific resistance of the films deposited in vacuo by 

 the cathode discharge is several times greater than the specific 

 resistance of the metal from which they were deposited. 



(2) The specific resistance of platinum films which have been 

 subjected to the same treatment remains constant above a thick- 

 ness of about 7x~L0~ lcm . Below this thickness the 3 increase of 

 specific resistance with decrease in thickness is very rapid. 



(3) Heat decreases the resistance of both silver and platinum 

 films, and the thinner the film the greater the decrease. In plati- 

 num films the greatest decrease is produced by the electric cur- 

 rent. 



(4) The values obtained for X, the mean free path of the cor- 

 puscle in the metal, are of the same order as those obtained from 

 the change of resistance produced by a transverse magnetic field. 

 —Phil. Mag., Dec, 1902, pp. 652-678. j. t. 



11. Formation of Ozone by Electrical Discharges in Oxygen. — 

 E. Warbury finds that the amount of ozone obtained from the 

 negative discharge is nearly three times that from the positive. 

 An expression is given for the amount of ozone formed. — Ann. 

 der Physik, No. 12, 1902, pp. 781-792. j. t. 



12. Examination of Spectroscopic Methods. — H. Konen exam- 

 ines the light of various metals produced in liquids — first by the 

 voltaic arc, and secondly by discharges from an induction coil. 

 He refers to the recent observations of Wilsing, and also to those 

 of Hale and Lockyer. He is not able to repeat all the phenomena 

 observed by these investigators, possibly on account of not employ- 

 ing the same conditions. — Ann. der Physik, No. 12, 1902, pp. 

 742-780. j. t. 



1 3. Does Motion through the Ether cause Double Refraction f — 

 The negative result of the Michelsen-Morley experiments, and the 

 suggestion of Fitzgerald and Lorentz that the stone platform of 

 Michelsen's apparatus altered its relative dimension when rotated, 

 leads Rayleigh to investigate whether the motion of the ether 

 can cause double refraction. The author concludes from his 

 experiments that there is no double refraction of the order to be 

 expected. — Phil. Mag., Dec, 1902, pp. 678-683. j. t. 



14. Scientia, Serie Physico-Mathematique : JVo. 19, IS J@lec- 

 tricite deduite de V Experience ; par E. Carvallo. Pp. 91. (C. 

 Naud, Editeur.) — In a most careful and logical manner M. Carvallo 

 has deduced from the experimental facts of electricity and magne- 

 tism the equations of Maxwell's theory and has made clear the sig- 

 nificance of the general process employed, by a number of well 

 chosen illustrations. The method is that of Maxwell — the appli- 

 cation of Lagrange's dynamical equations to electrical systems — 

 and there is no special originality of treatment ; but in clearness 

 of exposition and the avoidance of obscurities the work is 

 admirable and will doubtless make easier the task of many 

 students of Maxwell. A point of special interest is the treatment 



Am. Jour. Sci. — Fourth Series, Vol. XV, No. 85. — January, 1903. 

 6 



