MODEKtf HIGH FAKMING. 71 



in some cases to about one-third of the bulk, and arising from the 

 escape of the sulphurous acid gas. 



The rough product thus obtained is sometimes shipped without 

 any further refining, and is worth twenty dollars per ton ; but in 

 many cases it is further transformed into pure sulphur of a high- 

 er value, by sublimation and condensation in iron retorts. 



In the volcanic district of Reykjalid, in the North of Iceland, a 

 series of sulphur springs are met with, which afford a most inter- 

 esting study. 



They are of two kinds : those on the mountain slope consisting 

 of hot gases, which arise from the earth, charged with sulphuric 

 acid, hydrogen, sulphurous and aqueous vapors, and undergo de- 

 composition by coming into contact with the atmosphere. The 

 others at the foot of the mountain, being springs of black and boil- 

 ing mud. 



Mr. C. S. Forbes in his interesting volume on Iceland, her Vol- 

 canoes and Glaciers, gives a very graphic description of some of 

 these springs, and in one of his chapters, he says : 



" In the valley beyond, about fifty feet beneath us, lay a large 

 cauldron, twelve feet in diameter, in full blast, burning and seeth- 

 ing, with boiling blue mud that spluttered up in occasional jets, 

 five or six feet in height, diffusing clouds of vapor in every direction. 

 If a constant calm prevailed here, instead of ever-varying gales, the 

 sulphur sublimated from these sources would be precipitated in 

 regular banks ; as it is, it hardly ever falls twenty-four hours in the 

 same direction, the wind blowing it hither and thither, capriciously 

 distributing the sulphur shower in every quarter. 



" Such, with little variation, save in locality, were the numerous 

 Soufrieres and Solfataras that we visited, and they extend over a 

 space of twenty-five miles. The riches of the district consist not so 

 much in these numerous crusts of almost pure sulphur, as in the 

 beds of what I must be permitted to term sulphur earth, which are 

 promiscuously scattered in all directions, ranging from six inches 

 to three feet in thickness, and containing from 50 to 60 per cent, 

 of pure sulphur." 



