Prof. Magnus on Red and Black Sulphur. 17§ 



peculiar deportment of black sulphur^ of which we shall after- 

 wards speak. 



By evaporating the red solution, or distilling over a part of 

 the bisulphide of carbon, crystals will form in the liquid which 

 remains behind; they have the octahedral form of common 

 sulphur crystallized from bisulphide of carbon. The first which 

 form are yellow. After separating these and evaporating the 

 liquid still more, the crystals which then form have always 

 a redder tint. Ultimately a thick, tough, syrup-like, deep 

 red mass remains behind, from which no more crystals can be 

 obtained. 



So far the phseuomena are generally known. 



Black Sulphur. 



When remelted sulphur is treated several times with bisul- 

 phide of carbon, the colour of the solution becomes clearer, until 

 at last a residue, insoluble in bisulphide of carbon, is obtained. 

 This residue, which seldom exceeds one-third of the sulphur em- 

 ployed, falls usually to a brownish powder as long as it contains 

 bisulphide of carbon, but when dried appears almost entirely 

 yellow. 



This powder is a mixture of insoluble yellow and of black 

 sulphur. At the usual temperature it does not change, but at 

 100° C. it coalesces to a dark brown mass. By treating this 

 with bisulphide of carbon, a part of it dissolves to a weak reddish 

 liquid j if the insoluble part be again dried, and agaiu exposed 

 for some time to a temperature of 100°, another portion will 

 always be rendered soluble, and the remaining portion always 

 assumes a darker colour; so that when completely dried it 

 appears chocolate-brown. It now contains more black and less 

 yellow sulphur. In order to separate the two in this manner, 

 however, care must be taken not to expose them too long to a 

 temperature of 100° C, because at this temperature black sul- 

 phur is also converted into soluble yellow sulphur ; the former 

 requiring but a longer time for its conversion than the insoluble 

 yellow. It is best, therefore, as soon as the mass coalesces into 

 lumps, to take it out of the water-bath and treat it with bisul- 

 phide of carbon. If solid masses remain behind, they must be 

 powdered, and the powder warmed anew. The operation is 

 repeated in this manner until the colour of the powder obtained 

 after washing ceases to become darker. 



When this powder is fused at 300° C.*, and the fused mass 

 suddenly cooled by pouring it into water, or on a cold body such 



* In order not to exceed the proper temperature, which is of great im- 

 portance in the production of black sulphur, the fusions were always made 

 in metallic baths instead of over a free fife. 



N2 



