206 REACTION OF THE INTERIOR OF THE EARTH 



sphere, undergo only such changes of temperature as 

 are imparted to them by the ground through which 

 they issue forth ; 3rd, abnormally cold springs, in 

 which the low temperature is brought down from great 

 heights. ( 284 ) The greater the advance which has been 

 made of late years, by the happy application of chemistry 

 to geology, towards a knowledge of the mode of forma- 

 tion, and of the metamorphic alteration, of rocks, the 

 greater has been the importance attaching to the consi- 

 deration of those spring waters which circulate through 

 the crust of the earth, charged with different salts and 

 gases, and which when they break forth at the surface 

 as thermal waters have already completed the greater 

 part of their formative, metamorphic, or destructive 

 functions. 



c. Springs of Vapour and Gas, Salses, Mud-volca- 

 noes, Naphtha-flames. 



(Enlargement of the Picture of Nature in Cosmos, 

 Vol. I. pp.211 213.) 



In the general picture of nature in the first volume of 

 this work I have shown, by examples which have been 

 well made out, although they have not been sufficiently 

 attended to, that " Salses " in the different stages through 

 which they pass, from eruptions accompanied by flames 

 to mud emitted quietly, form, as it were, an interme- 

 diate link between hot springs and volcanoes proper ; 

 which latter throw up molten earths, in the shape 

 of disconnected scoriae, or, as newly formed and often 

 variously superposed rocks. Like all transitions and inter- 



