478 



Intelligence and Miscellaneous Articles, 



Flint Glass. 



«K7° 



57°37'-5; n'= 1-577. 



A= 2°31'-5. 

 «= 1-6218. 



z. 



Observed. 



Calculated. 



A. 



o 



30 



0-070 



0071 



-0-001 



40 



0084 



0093 



-0-009 



50 



0120 



0133 



-0-013 



55 



0-161 



162 



-0001 



60 



0-203 



0-203 



0000 



65 



0-254 



0-257 



-0003 



70 



0-327 



0-330 



-0-003 



The differences between the intensity calculated from Fresnel's 

 formula for light polarized parallel to the plane of incidence and 

 that directly observed fall quite within the range of the errors of 

 observation ; for the maxima and minima of the individual obser- 

 vations diverge from one another, on the average, 0*04. — -Monats- 

 bericlit cler Icon.preuss. Akademie derWissensch. zu Berlin, July 1874>- 

 pp. 511-516. 



POLAEIZATIOX OF THE PLATES OF COKDEXSEES. BY A. S. THAYEB. 



It is well known that in polarization-batteries, of which Plante's 

 battery is a type, a combination of the ions resulting from elec- 

 trolysis takes place when the plates of the battery are connected* 

 and a current results which slowly diminishes in strength. In the 

 case of condensers made with solid dielectrics the same diminishing 

 current is observed ; and the following experiments would seem to 

 show that it might be due to an electrolysis or decomposition of 

 the material separating the plates of tinfoil. The experiments 

 consisted in placing condensers of various kinds in a circuit, through 

 which a -current- was- made to-pass by two Bunsen's cells, and 

 noting their changes. The plates of the condensers were of tinfoil, 

 and had an area of about fifteen square inches. The experiments 

 were as follows :— - " " : """ 



(1) The dielectric used was a sheet of dry glazed paper. The 

 condenser could not be charged so as to give a perceptible dis- 

 charge. 



(2) When a sheet of glazed paper, moistened with shellac, was 

 substituted for the dry paper, the discharge was sufficient to send 

 the light off the scale of the galvanometer, and continued for some 

 minutes. - - 



(3) Dry goldbeaters' skin was used as a dielectric ; and no deflec- 

 tion could be obtained. 



