528 Prof. Magnus on the AUotropic Conditions of Sidphur, 



But the soluble part of soft sulphur contains still two different 

 modifications of sulphur. For if a part of the bisulphide of 

 carbon be distilled off from the solution, and the liquid be then 

 allowed to cool, octahedral sulphur crystallizes out. If this be 

 removed from the liquid and a fresh quantity of bisulphide of 

 carbon be distilled off, so that on cooling some more octahedral 

 sulphur is obtained, there remains, after repeating this operation, 

 a tough mass which can be drawn out in threads. This still 

 contains sulphur. If left to itself the bisulphide of carbon 

 evaporates, and the sulphur separates as a crummy mass. This 

 sulphur was manifestly still more soluble in bisulphide of car- 

 bon than octahedral sulphur, for it separated after the latter. 

 Notwithstanding this, after it has been once separated from the 

 bisulphide of carbon, it does not again dissolve in it. If the 

 crummy mass, as is sometimes the case, still contains small 

 crystals of sulphur, these are dissolved, but the crummy sulphur,, 

 is insoluble even in boiling bisulphide of carbon. 



If the soft sulphur, from which the crummy mass has been 

 prepared, has been only once heated to 300° C, and if all con- 

 tact with the fingers has been avoided, the crummy mass has a 

 pure yellow colour. If, on the contrary, the soft sulphur has 

 been several times melted and poured out, it appears more or 

 less red-coloured. On this account I have hitherto designated 

 it as red sulphur. Since it is soluble in bisulphide of carbon, 

 but once separated from this solution does not again dissolve in 

 it, it is distinguished as well from the soluble as from the inso- 

 luble sulphur, and must be regarded as a particular allotropic 

 modification. It comports itself in this respect just like silica, 

 which I have also already* noticed with regard to red sulphur. 

 With the exception of the colour, which, as was mentioned, may 

 vary, it exhibits all the properties which have been ascribed to it. 

 If it is melted and slowly cooled, it changes into common soluble 

 sulphur. 



The remarkable comportment of the quickly cooled soft sul- 

 phur appears to depend on the presence of this modification ; 

 for if soft sulphur be allowed to lay so long that it has become 

 hard and brittle, for which, as is known, several days arc neces- 

 sary, it contains much less of this modification than in the fresh, 

 soft condition, as is seen on comparison of the columns 3 and 7 

 of the following Tables, in which the experiments have been 

 collected. 



soufre sous Vinfluence de la chaleur et des dissolvants {Ann. de Chim, 

 3 ser. xlvii. 99), that he found 35 per cent, in it. 

 * Phil. Mag. ser. 4. vol. viii. p. 182. 



