and Detonating Matches. 127 



against the bottom of the vessel, the crudities are tossed up 

 and incorporated with the mass. 



The sulphur of commerce occurs in three prevailing colours ; 

 lemon yellow verging on green, dark yellow, and brown yellow. 

 As these different shades result from the different degrees of 

 heat to which it has been exposed in its original extraction on 

 the great scale, we may thereby judge to what point it may 

 still be heated anew in the refinery melting. Whatever be the 

 actual shade of the crude article, the art of the refiner consists 

 in regulating the heat, so that after the operation it may pos- 

 sess a brilliant yellow hue, inclining somewhat to green. 



In seeking to accomplish this purpose, the sulphur should 

 first be sorted according to its shades; and if a greenish 

 variety is to be purified, since this kind has been but little 

 heated in its extraction, the fusion may be urged pretty 

 smartly, or the fire may be kept up till every thing is melted 

 but the uppermost layer. 



Sulphur of a strong yellow tinge cannot bear so great a heat, 

 and therefore the fire must be withdrawn whenever three- 

 fourths of the whole mass have been melted. 



Brown-coloured brimstone, having been already somewhat 

 scorched, should be heated as little as possible, and the fire 

 may be removed as soon as one-half of the mass is fused. 



Instead of melting, separately, sulphurs of different shades, 

 we would obtain a better result, by first filling up the pot to 

 half its capacity, with the greenish -coloured, putting over this 

 layer, one quarter volume of the deep yellow, and filling it to 

 the brim with the -brown-coloured. The fire must be extin- 

 guished as soon as the yellow is fused. The pot must then be 

 closely covered for some time ; after which the lighter impuri- 

 ties will be found on the surface in a black froth, which is 

 skimmed off, and the heavier ones sink to the bottom. The 

 sulphur itself must be left in the pot for ten or twelve hours, 

 after which it is laded out into the crystallizing boxes or casks. 



Distillation affords a more complete and very economical 

 means of purifying sulphur, which was first introduced into the 

 French gunpowder establishments, when their importation of 

 the best Italian and Sicilian sulphur was obstructed by the 

 British navy. Here the sulphur need not come over slowly in 



