On Sal Nitrum and Nitro- Aerial Spirit 177 



steeped in a sort of moisture to the depth of several 

 feet, and that aqueous particles escape from it only 

 very slowly. And hence it is that the ground 

 wet with showers can be dried up only after a long 

 time. It corroborates this view that if a pair of cuts, 

 several feet deep and of sufficient length, are dug in 

 almost any soil so that they meet at their lowest part, 

 the drops of waterflowing here and there from the banks 

 and uniting at last at the bottom, will make an artificial 

 spring or rather rivulet. And this shows why it is that 

 spring-waters well forth with greater or less abundance 

 according as the weather has been wet or dry. Now 

 this would by no means be the case if springs were 

 derived from the sea and not from the air. 



Further, it must, I think, be granted that nearly all 

 the mountains in every part of the world consist 

 of saline-sulphureous matters such as vitriolic or 

 aluminous marchasites and the like. 



I remark, in the last place, that if saline-sulphureous 

 earth of this sort be wetted with rain-water it will 

 effervesce and grow warm. For if marchasites or 

 saline-sulphureous masses, such as vitriolic and similar 

 salts are produced from, be exposed to moist air and 

 rainy weather they will soon effervesce markedly. 

 Nay, if any saline-sulphureous mineral, recently dug 

 up, is wetted with rain-water it will after a short time 

 effervesce and grow warm. 



Let us next inquire why saline-sulphureous minerals 

 of this sort effervesce when wetted with rain-water, 

 for it is to be supposed that the heat of the thermal 

 springs results from the same cause. And we may 

 indeed suppose that the aerial particles which are 

 mingled with almost all water, but especially with 

 rain-water, contribute in no small degree to produce 

 the said effervescence. For that air is mixed with 



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