222 Von Nidda on the Mineral Springs of Iceland. 



sulphur, gypsum, alum and sulphate of iron are the most com- 

 mon products. 



In the neighbourhood of Cape Reikianaes there are several 

 water and gas springs ; but none particularly remarkable. 



The other opening of the great longitudinal valley is not less 

 interesting. The Myvatn lake is to be regarded as the centre 

 of the volcanic phenomena of this district. Among the nume- 

 rous cones of eruption scattered round it, the most remarkable 

 are the Leirhnukur, and the Krabla, on the north-east side of 

 the lake ; and the Haedubreid on the south side. Large streams 

 of lava cover the district. 



In the Myvatn lake there are several hot springs, which are 

 recognised by the great clouds of vapour rising from various 

 points on the surface of the water. 



The celebrated Namar or Sulphur mountains, lie to the 

 north-east of the Myvatn lake, between it and the Leirhnukur 

 and Krabla. They are about one mile long, and a quarter of 

 a mile broad. The soil consists of variously tinted clays. In- 

 numerable little hillocks, three to four feet in height, rise from 

 the surface, and the hot gaseous streams burst through their 

 summits. It is not altogether safe to walk on the Namar. The 

 clay, constantly moistened by the watery vapours, is so slippery 

 and soft, that at every instant one is afraid of sinking in the 

 mass. It is only necessary to pierce with a stick the upper and 

 somewhat cooled clayey crust, in order to ascertain how high a 

 temperature prevails in the deeper layers ; for immediately a 

 hot stream of gases escapes from such an aperture. Sublimed 

 sulphur occurs everywhere, and being collected by the inhabi- 

 tants, forms rather an important article of traffic. 



Henderson* gives a remarkable and interesting description of 

 the hot mud springs which he saw in the crater of the Krabla. 

 This traveller, when he reached the base of the Krabla, descried 

 a vast volume of smoke, rising to a considerable height, at re- 

 gular periods, from a break about two-thirds up the south-west 

 side of the mountain. With much difficulty he ascended the 

 acclivity, which was covered with loose masses of tuffa and 

 pumice. At length he gained the edge of a deep gulley, at the 

 bottom of which was situated a circular pool of black liquid 

 Journal of a Residence in Iceland, vol. i. p. 170. 



