Prof. Magnus on Red and Black Sulphur, 185 



If in a state of fine powder, it coalesces when heated; if em- 

 ployed in larger pieces, it retains its form unchanged. 



If pure red sulphur be fused at 110° to 130° C, and suddenly 

 cooled as soon as it has become liquid, a red molten msss will 

 be obtained which shows a crystalline structure at the surface. 

 By treating this with bisulphide of carbon, a portion of it dis- 

 solves and gives a reddish solution ; the greater part is insoluble. 



Red sulphur, when fused at 130° to 150° C, is soluble, and 

 gives a red solution. 



When fused at 300° C. and suddenly cooled, black sulphur is 

 obtained which possesses all the properties of the above-mentioned 

 black sulphur, and, like the latter, remains for a long time quite 

 soft and ductile. 



Black sulphur, when prepared in this manner, always contains 

 small quantities of yellow sulphur, inasmuch as the heating to 

 300°, and the subsequent cooling, cannot be momentarily effected; 

 but with this exception it is pure, whilst the black sulphur pre- 

 pared according to the method above mentioned, contains all the 

 impurities, insoluble in bisulphide of carbon, which were present 

 in the yellow sulphur used in its preparation. 



Red sulphur, when sublimated, gives yellow, without produc- 

 tion of residue. In a similar manner to that already mentioned, 

 black sulphur, when sublimated, also gives yellow. 



This easy conversion of red as well as of black sulphur into 

 soluble yellow sulphur at high temperatures, is the reason why 

 both can be obtained only in so small quantities. 



Black sulphur can only be obtained from red by heating the 

 latter to 300° C. and then suddenly cooling it. Nevertheless 

 the deportment and external appearance of both are so essentially 

 different, that it appears perfectly justifiable to consider them as 

 two different modifications. Soluble red sulphur dififers as much 

 from insoluble red and from black as these do from one another, 

 hence it is advisable to consider this also as a particular modifi- 

 cation ; and we have as grea-t cause for so doing, as for consider- 

 ing soluble and insoluble silicic acid as two difi"erent modifications. 



According to the above, the following are the results : — 



1. When properly heated sulphur is suddenly cooled, a part 

 of the same is converted into insoluble yellow sulphur. One- 

 third of the weight of flowers of sulphur consists of such insoluble 

 sulphur. 



2. By repeated fusings at a high temperature, and sudden 

 coolings, sulphur assumes a red-brown colour. In this state 

 Deville calls it red sulphur. It would be more convenient to 

 call it remelted sulphur, in order to distinguish it from actual 



