CHEMICAL SCIENCE. 295 



such an oil would be of great importance, not only in a commercial point 

 of view, but in a hygienic one also. Bulletin ck la Socict* d' Encourage- 

 ment. 



MELTING POINT AND TRANSFORMATION OF SULPHUR. 



Sir B. C. Brodie, F. R. S., read a paper on sulphur, at a recent meet- 

 ing of the London Royal Society, in the course of which he remarked 

 that, in the various treatises of chemistry, great discrepancies exist respect- 

 ing the melting point of sulphur, so much so that he was led to make sev- 

 eral experiments, with the view of discovering, if possible, the true laws 

 which regulate the transformation of sulphur and its liquidation. The 

 melting point of sulphur varies according to its allotropic condition. This 

 condition is readily altered by heat, and invariably, without peculiar pre- 

 cautions, by melting. Hence the temperature at which sulphur melts is 

 different from that at which it will solidify, or at which, having been 

 melted, it will melt again. The melting point of the octohedral sulphur is 

 114.5. But from the facility with which this sulphur, when heated even 

 below its melting point, passes into the sulphur of the oblique system, 

 this fact may readily be overlooked. When this sulphur, even in the 

 shape of fine powder, is heated for the shortest time between 100 and 

 11-4.5 , this change cannot be avoided. For the transformation of large 

 crystals a longer time is required. At a certain point the crystals become 

 opaque, and are often broken in pieces at the moment of the change. 

 "When, sulphur has been converted by heating a sufficient length of time, 

 it acquires a fixed melting point of 120. This is the melting point of 

 the oblique prismatic sulphur. If sulphur thus converted be carefully 

 melted so as to raise the temperature as little as possible above the melting 

 point, no sensible difference will be observed between the point of melting 

 and that of solidification. To obtain this fixed melting point of 120, 

 care must be taken that the transformation of the sulphur has been thor- 

 oughly effected. If this be not done, it may melt at any point between 

 114.5 and 120. If, however, the temperature of the melted sulphur be 

 raised above its melting point of 120, the point of solidification will be 

 altered, and will lie even below the first melting point of 114.5. The 

 sulphur which is insoluble is bisulphide of carbon. This is prepared 

 by extracting the hardened viscid sulphur with that re- agent, which 

 has a melting point considerably above 120, but which the author has 

 not been able to determine with precision. It is stated in chemical 

 treatises that the opacity, which on solidification comes over the melted 

 sulphur, is due to the transformation of the oblique prismatic into the oc- 

 tohedral sulphur, and the consequent disruption of the crystal. To this 

 cause is also attributed the evolution of heat, which has been observed in 

 solid sulphur immediately after cooling. There are, however, no sufficient 

 grounds for this view, and some of the observations are decidedly adverse 

 to it. On extracting melted sulphur which had become opaque with the 



