Dr. Tyndall on Diamagnetism and Magnecrystallic Action. 17i 

 Table III. — Sulphur spheres, 13*4 millims. diameter. 



The sulphur from which these balls were made was the mate- 

 rial of commerce. After the experiments one of the balls was 

 placed in a clean porcelain crucible and brought over the flame 

 of a spirit-lamp ; the sulphur melted, ignited, and disappeared 

 in sulphurous acid vapour. A portion of solid substance re- 

 mained in the crucible unvolatilized. This was dissolved in hy- 

 drochloric acid, and ferrocyanide of potassium was added; the 

 solution turned immediately blue ; iron was present. The other 

 ball was submitted to a similar examination, and with the same 

 result ; both balls contained a slight admixture of iron. 



In this case, therefore, the two opposing forces, magnetism 

 and diamagnetism, were present, but we find the equation 

 >v/T=?^ tan a fulfilled notwithstanding. Did one of the forces 

 increase with the ascending magnetic power more quickly than 

 the other, this result would be impossible. 



Flowers of sulphur were next tried, but found to contain a 

 considerable quantity of iron. I have to thank Prof. Magnus 

 for a portion of a native crystal of the substance obtained in Si- 

 cily, which upon trial was found to be perfectly pure. From 

 this, two small pellets were formed and laid upon the torsion- 

 balance ; they gave the following results : — 



Table IV. — Spheres of Native Sulphur. 

 /i=2-65. 



The next substajice chosen was calcareous spar. The comers 

 of the crystalline rhomb were first filed away, and the mass thus 

 rendered tolerably round ; it was then placed between two pieces 

 of soft sandstone, in each of which a hollow, like the cavity of 

 a bullet-mould, had been worked out. By turning the stones, 



