570 Chronicles of Science. [Oct., 



netic rotatory power of liquids, the results of which will he shortly 

 published. The first portion of this work is devoted to the descrip- 

 tion of the apparatus and processes of experimentation ; the second 

 part contains the results of the determination of the magnetic 

 rotatory power of some liquids. As a curious anomaly the author 

 mentions that taking water as unit, the coefficient of the magnetic 

 rotatory power of monohydrated sulphuric acid is * 750, and that 

 coefficient is, for liquid anhydrous sulphurous acid, equal to 1 * 240 

 at a temperature of 12°. The third part of this work is devoted to 

 the study of the influence of the temperature on the magnetic rota- 

 tory power. In the fourth part, the author gives the results of his 

 investigations of the magnetic rotatory power of a mixture of two 

 liquids as compared with that each of these liquids possesses sepa- 

 rately. The fifth part contains the results obtained by experiment- 

 ing with two isomeric liquids. 



In some experimental researches on the length of duration of 

 the electric spark, MM. Lucas and Cazin employ two transparent 

 discs placed upon the same axis. One of these discs is a fixture, 

 while a more or less rapid rotatory motion can be imparted to the 

 other. Upon both discs are painted the same number of opaque 

 stripes in the direction of the radius. When, therefore, an electric 

 spark is observed through these discs, a certain amount of speed 

 having been imparted to the movable one (the apparatus being 

 placed in a darkened room), it is clear that by the light emitted by 

 the spark a certain number of coincidences of the movable and fixed 

 stripes may be observed, and these coincidences may serve to calcu- 

 late the period of duration of the spark. 



Dr. Demayes describes at length an apparatus constructed by 

 him, which appears to be an improvement on Siemens' electro- 

 magnetic apparatus ; while making from 250 to 280 revolutions a 

 minute, the lifting power of the magnet is 70 kilos., and under 

 similar conditions a platinum wire, ■ 8 mm. thick and 20 centim. 

 long was rendered red-hot, and iron wire of the same thickness 

 fused ; the machine produces per second of time half a cubic centi- 

 metre of gas by the decomposition of water. 



In a recent instalment of his researches on electro-capillary 

 action, which have occupied M. Becquerel for a series of years, he 

 announces the artificial formation of the oxychloride of copper in 

 crystalline state, and exactly similar to that found in the copper 

 mines of Peru and Chili, and known as atacamite. This formation 

 has taken no less than fifteen years. 



Mr. E. W. Blake, jun., has described a method of producing by 

 the electric spark figures similar to those of Lichtenberg. The 

 method consists in throwing the discharge upon the surface of a 

 fusible non-conducting body. If the body be near its fusing-point 



