Resistance and other Properties of Sulphur. 



14b* 



Temperature. 



290 to 310° Cu almost eaten away. 

 Pb as before. 



Mg, Zn, and Sn not attacked. 



Again pieces of copper, of equal sizes and weights, were cut from 

 the same sheet. After having been carefully cleaned and weighed 

 they were exposed to sulphur at different temperatures for 15 minutes, 

 after which they were carefully cleaned and re-weighed. 



Weight of 

 copper used. 



Temperature. 



Loss of 

 weight. 



Rise of 

 temperature. 



(1) 11-34 grams. . 



240° 



0-89 



12° 



(2) 



280 



0-92 



11 



m 



300 



1-62 



30 



The last column gives the increase of temperature due to the union 

 of the copper and the sulphur. It occurred two minutes after the cold 

 copper was introduced. At first there was a fall of 4° in the two first 

 experiments, and 5° in the last ; this was followed by a rise. The 

 lamp was withdrawn when the temperature rose to that at which the 

 experiment commenced. At the end of two minutes the rise given 

 in the fourth line was observed. 



It appears, therefore, that there is a gradually increasing action up 

 to 290°, or about that temperature, and above that a considerable 

 increase. The point of change in resistance, 290°, appears to be one of 

 considerable importance, carrying also the fluidity, boiling point, and 

 chemical affinity, &c. 



Action of Light on Sulphur. 



That the metals of the same group in the arrangement according 

 to the Periodic Law have properties in common is well known. Thus 

 chlorine, bromine, and iodine belong to the same group, and are in 

 many respects very similar bodies. Sulphur belongs not only to the 

 same group as selenium, but is the next element in front of it. Natur- 

 ally, therefore, we expect that they will have properties in common, 

 and possibly the action of light in the case of selenium may be 

 shared in an inferior degree by sulphur. This appears more pro- 

 bable from the well-known fact that a saturated solution of sulphur 

 in bisulphide of carbon is rendered turbid by direct sunlight, part 

 of the sulphur being changed and becoming insoluble in that liquid. 

 A portion of the sulphur undergoes the same change when exposed to 

 a high temperature. In order that the sulphur used in the experi- 

 ment might be as sensitive as possible to light, it appeared desirable 



