Magnetic Influence of Solar Light. 



255 



in form, becoming octohedrous by exposure for a few minutes 

 to the action of the sun, and that by the same cause, pris- 

 matic crystals of nickel, without changing their external 

 form, had become internally so altered as to exhibit when 

 broken up, a series of octohedrons with square bases. Here, 

 therefore, we have proofs of powerful internal molecular 

 action consequent on exposure to the sun, and although it 

 would be unwarrantable for me to conclude that such action 

 had taken place in the steell needles also, the passing allusion 

 I have made to M. Mitscherlich's results, will not be mis- 

 placed, if it shews that while no changes of magnetic condition 

 took place in them, it is not impossible that changes of a differ- 

 ent nature may have done so, and may have produced those 

 dynamical differences to which reference has been made. 



2nd. — Experiments with steel and iron cylinders in dif- 

 ferent degrees of Oxidation. 



It being an established fact that a certain degree of 

 oxidation pervading the mass, or distributed on the surface 

 of steel or iron increase their susceptibility of magnetic 

 influence, I was desirous of discovering whether the action 

 of light could be made perceptible by using cylinders in 

 this condition. The following experiments, were accordingly 

 made with this view: — 



TABLE X. 



Shewing Duration of Oscillations of Needle D. before exposure. 



fExp i 



o . 



Hour of 

 Day. 



th of 

 die. 



Diam. of 

 Needle. 



o 

 6 



-w 



A. M. 



P. M. 



Leng 



Nee 





Jan. 







In. 



In. 



1 



20th 



10| 





4 



0.033 



2 













3 













4 













5 













66o 



Sums. ... 

 Means. 



O 02 



525 O 



10 

 10 

 10 

 10 

 10 



50 



e -J 



o — j 



H 



Q o 



Sea. 

 261 

 259 

 258 

 260 

 257 



A e3 



EH 



1205 



25.91 



Remarks. 



