24 



March 30, 1854. 



THOMAS BELL, Esq., V.P., in the Chair. 

 The following papers were read : 



I. "Note on the Melting-point and Transformations of Sul- 

 phur." By B. C. BRODIE, Esq., F.R.S. Received March 

 30, 1854. 



In the treatises of chemistry where the results of different ob- 

 servers are collected, various statements will be found as to the 

 melting-point of sulphur. The numbers given in Gmelin's Che- 

 mistry vary from 104' 5 C. to 1 12* 2 C., but of five chemists cited, no 

 two agree as to this apparently simple fact. There is evidently 

 some peculiarity about this melting-point which is the cause of these 

 anomalous results. In some experiments on allotropic substances, 

 in which I have been engaged, I had occasion to submit this ques- 

 tion to a more searching inquiry than it had hitherto received, in 

 which I have discovered the cause of these discrepancies. In the 

 present note I will briefly give the results at which I have arrived, 

 reserving the details for a further and more full communication. 



The melting-point of sulphur varies according to its allotropic 

 condition. This condition is readily altered by heat, and invariably, 

 without peculiar precautions, 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, as crystallized from 

 the bisulphide of carbon, is 114'5 C. 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, in the state of fine powder, is 

 heated even for the shortest time between 100 and 114 '5, this 

 change cannot be avoided. For the transformation of large crystals 



