Masterpieces of Science 



of the hot springs at Bath, for example, have a 

 temperature of 120 F. Still hotter springs 

 occur in many countries; and, in volcanic districts, 

 even the boiling point is occasionally reached. 

 The most remarkable of these hot springs are 

 those known in Iceland as geysers. Jets of 

 boiling water with clouds of steam are intermit- 

 tently thrown high into the air with great force and 

 accompanied with loud explosions. The water 

 generally holds silica in solution and this siliceous 

 matter is deposited around the mouth of the hole 

 as an incrustation called sinter. Although the 

 Geysers of Iceland are best known, similar 

 springs are found in New Zealand, and also in 

 the Rocky Mountains of North America. No 

 fewer than 10,000 hot springs, geysers, and hot 

 lakes are said to exist within the area of the 

 Yellowstone Park. 



In some localities, hot water issuing from the 

 ground is mixed with earthy matter ; and streams 

 of thick mud accumulate around the openings, 

 so as to form conical hills, known as salses, or 

 mud volcanoes. Such eruptions of mud, vary- 

 ing considerably in consistency and in tempera- 

 ture, occur, for example, in the Crimea and on 

 the shores of the Caspian Sea. In other cases, 

 hot vapours issue from cracks in the ground, 

 as at the Solfatara, near Naples, where the va- 

 pours are charged with sulphur. A large in- 

 dustry has sprung up in the Tuscan Maremma, 

 by utilizing the hot vapours which issue from 

 smoking cracks, known as soffioni, and contain 

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