186 Prof. Magnus on Red and Black Sulphur. 



rcrf sulphur. About a third of the same is soluble in bisulphide 

 of carbon. This third has a yellow colour, but consists partly of 

 yellow and partly of insoluble black sulphur. 



3. The above insoluble residue, when warmed in the water- 

 bath, becomes soft and greasy; and after cooling, one portion 

 (the yellow) is soluble, inasmuch as this, at 100° C, is more 

 easily converted into the soluble modification than the black. 



By repeatedly treating the insoluble residue at 100° C, the 

 residual powder assumes a chocolate-brown colour. 



4. This powder, when fused at 300° C. and suddenly cooled, 

 gives a perfectly black, greasy, ductile mass, which requires some 

 time to solidify, and has then a glassy appearance. This black 

 sulphur does not dissolve, or does so very slightly, in bisulphide 

 of carbon, alcohol, sether, benzole, oil of turpentine, and chlo- 

 roform. 



5. Black sulphur, when kept for some time at a temperature 

 of 100° C, dissolves in bisulphide of carbon. The solution con- 

 tains much yellow, together with a little red sulphur. 



6. If black sulphur be exposed for a short time only to a tem- 

 perature of 130° to 150° C. it will, when cool, have a brown 

 colour and crystalline structure. It is now soluble in bichloride 

 of carbon. The solution contains much red and little yellow 

 sulphur. 



7. By evaporating the solution slowly, crystals of yellow sul- 

 phur are obtained which appear the more red the more concen- 

 trated the solution ; at last a mother-liquor is left behind, which 

 after some time forms a solid red mass. 



8. This hardened mass is not again soluble in bisulphide of 

 carbon. By proper treatment it is granulous, and has a cochi- 

 neal-r^ colour. 



9. This red sulphur, when exposed to a temperature of 130° 

 to 150° C, fuses to a red mass of crystalline structure, of which 

 a part is soluble in bisulphide of carbon. 



10. Red sulphur, when heated to 300° C. and suddenly cooled, 

 gives black sulphur. 



Accordingly, the following are the several modifications of 

 sulphur : — 



1. Soluble prismatic yellow, 



2. Soluble octahedral yellow, 

 8. Insoluble yellow, 



4. Insoluble red, 



5. Soluble red, 



6. Black sulphur. 



The remelted and suddenly-cooled sulphui* contains soluble 

 yellow, insoluble yellow, black and soluble red sulphur. 



