I 





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Chemistry and Physics. . 113 



by experiment, that the rotation of the point of suspension will not 

 affect the plane of vibration of the pendulum, and the result will be 

 the same as before ; the plane of vibration will appear to revolve uni- 

 formly, making a complete revolution in twenty-four hours. If we 

 transfer the point of suspension from the pole to the equator, this 

 point will then revolve with the earth and the plane of vibration will 

 undergo no apparent change : but if we transfer the pendulum to 

 a point between the pole and the equator, it is clear that while the 

 point of suspension will itself revolve uniformly with the earth, the 

 plane of vibration of the pendulum will be carried round but less rap- 

 idly than the earth, the result will therefore be that the plane of vibra- 

 tion will move with reference to the earth from east to west, but more 

 slowly than at the pole. Foucault finds, by two different methods, that 

 the angular motion of the plane of vibration is equal to the angular 

 motion of the earth in the same time multiplied by the sine of the lat- 

 itude. The experiment in question has been made upon a large scale 

 in the Pantheon at Paris, the length of the cord, and consequently the 

 time of vibration of the pendulum allowing the apparent motion of the 

 plane of vibration to become very distinctly evident after only a few 

 oscillations. — C07npf.es Rendus^ xxxil, p. 135. [The experiment has 

 been repeated in this country and England.] 



_ 3, Equivalent of Bismuth. — Schneider has made a new determina- 

 tion of the equivalent of bismuth, and has obtained results which appear 

 to be well worthy of confidence. Commercial bismuth was dissolved in 

 pure nhric acid, the solution precipitated by the addition of water, and 

 the resulting basic nitrate thrown upon a filter, and well washed and 

 dried; the dry salt was then mixed with black flux and the mixture 

 Ignited \ the regulus of metallic bismuth thus obtained was fused several 

 times with the addition of a small quantity of nitre, then again fused 

 Jjepeatedly alone, and finally poured out upon a clean porcelain plate. 



J^he mode of determination employed was that of oxydation, as the* 

 reduction of the oxyd by means o? hydrogen takes place with difficulty 

 and at a temperature at which some of the oxyd is volatilized. A 

 known weight of the metal was dissolved in pure nitric acid, the solu- 

 tion evaporated to dryness and ignited, and the resulting oxyd weighed, 

 i'or the precautions used to prevent loss by ^e mechanical transfer of 

 small portions of the solution, and other calles, we must refer to the 

 original memoir. As a mean of eight experiments nearly agreeing with 

 each other, it was found that 100 parts of oxyd of bismuth contain 



Bismuth, 

 Oxygen, 



89-655 



10-345 



from which the equivalent of bismuth is found to be 2599-95, which of 



2600. 



uently 



^urse IS sufficiently nearly represented by the round number 

 ^he old equivalent determined by Lagerhjelm, 266075, is conseq 

 "^«ch too high, and bismuth must be placed among those elements whose 

 equivalents are exact multiples of that of hydrogen, 2600=12-5X208. 



^fW^«n-, 1851, 2,303. 



.4- Equivalent of Tangs^en.-— Marchand and Schneider have deter- 

 mined the equivalent of tungsten both by the oxydation of the metal 

 and by the reduction of tungstic acid in a current of hydrogen* As a 



Second Sehibs, Vol. XTI, No. 34.— July, 1861. 15 



