54 PHYSIOGRAPHY. CtASS II. 



OBSERVATIONS. 



1. The usual division of the present species into common 

 and volcanic Sulphur depends upon the geological situation 

 of their natural repositories. The second kind is a product 

 of sublimation ; it appears in the shape of crusts, superfi- 

 cial coatings, stalactites, or also in loose mealy masses ; and 

 consists generally of columnar particles of composition, not 

 unfrequently terminating in crystalline points. It occurs 

 sometimes also in very considerable crystals. Common 

 Sulphur has been farther subdivided into compact and earthy, 

 the last of which comprehends those varieties which, on 

 account of the smallness of the individuals in the granular 

 compositions, appear as a friable mealy powder. 



2. The prismatic Sulphur is the pure sulphur as it oc- 

 curs in nature, occasionally mixed with bitumen or clay. 

 It acquires resinous electricity by friction, is easily in- 

 flammable, and burns with a blue or white flame, and a 

 pungent smell of sulphurous acid. It is insoluble in water, 

 but unites readily with potash or soda. It may be obtain- 

 ed crystallised by sublimation, or still more easily from so- 

 lutions in liquids. Professor MITSCHERLICH has shewn, 

 that the forms of sulphur, crystallised from fusion, are in- 

 compatible with those of the present species. They are 

 hemi-prismatic, being generally oblique rhombic prisms of 

 90 32', the terminal face of which is inclined to the ob- 

 tuse edge of the prism, which is itself commonly replaced, 

 at an angle of 95 46' ; a horizontal prism in the direction 

 of the short diagonal measures 90 18'. It occurs almost 

 always in regular compositions. The crystals are at first 

 transparent, but they soon become opake. It has not yet 

 been observed in nature. 



3. The prismatic Sulphur is principally met with in 

 beds of prismatoidal Gypsum-haloide, or in the accompany- 

 ing strata of clay. It is generally associated with rhom- 

 bohedral Lime-haloide, and often also with prismatoidal 

 Hal-baryte. In veins it occurs with pyramidal Copper- 

 pyrites, hexahedral Lead-glance, hemi-prismatic Sulphur, 



