764 NUMERICAL CONSTANTS. 



1296. MAGNETIC ROTATORY POWERS. The most accurate 

 experiments on the determination in absolute value of what is 

 known as Verde? s constant that is to say, the rotation of the 

 plane of polarization between two points whose difference of 

 magnetic potential is equal to the C.G.S. unit were made by 

 bisulphide of carbon. 



For temperature zero, and the ray D, the values given previously 

 (916), according to Gordon, H. Becquerel, and Lord Rayleigh, 

 vary from 0*0426' to 0*0463'. The most recent experiments of 

 M. Koepsel* and of M. H. Becquerel f have given respectively 

 0*04297' and 0*04341'. 



Bisulphide of Carbon. 

 Variation with temperature, according to M. Bichat. } 



R = R [i - 0*00 1 o4/- 0*0000 1 4/ 2 ]. 

 Rotation for the various rays of the spectrum .at 25. 



c. D. - E. F. G. 



0*0319' 0*0415' 0*0637' 0*0667' 0*0920' 



Liquids. \ 

 (Ray D. Temperature, 15.) 



Sulphuric Acid, monohydrated 0*0104' 



Methylic Alcohol 106 



Propylic 117 



Nitric Acid, ordinary . 123 



Butylic Alcohol 124 



Distilled Water . 130 



Amylic Alcohol 131 



Chloroform 160 



Chloride of Carbon 170 



,, Silicon , . 187 



Hydrochloric Acid, pure 206 



Xylene 221 . 



Toluene 242 



Benzine 268 



* KCEPSEL. Wied. Ann., Vol. xxvi., p. 456. 1885. Observation made at 

 1 8, and reduced by Bichat's formula. 



t H. BECQUEREL. Ann. de Chim. et de Phys. [6], Vol. vr., p. 245. 1885. 

 The observation was made near zero. 



\ BICHAT. Journal de Physique, Vol. vni., p. 204. 1879. 



VERDET. Ann. de Chim. et de Phys. [3], Vol. LII., p. 129. 1857. 



|| H. BECQUEREL. Ann. de Chim. et de Phys. [5], Vol. xn., p. 34. 1877. 



