170 A. E. Hunt — Superheated Water. 



water highly charged with salts ; but water it is, and not gas . . . "" 

 (Trans. Dev. Assoc, 1889, p. 244). 



Granted this first step, and I believe we shall ultimately reach 

 the following conclusion, viz., that our planet consolidated first on 

 the surface of the molten spheroid, in the form of a floating slag ; 

 that all the plutonic rocks, as we know them, are the result of 

 the world-old conflict between the waters on the surface and the 

 heat beneath the surface ; and that all the water we see locked up 

 in granites and schists, whether in the form of water or of hydrous 

 minerals, came originally from above and not from below. It will 

 no doubt be considered a very large order, but I believe there is 

 a suflBcient deposit in the bank of fact to meet the whole draft. 



Perhaps, to make sure, I had better explain that by 'meteoric' 

 water I only meant water derived from the atmosphere, as dis- 

 tinguished from water derived from the sea. 



Professor Beck makes the important incidental remark that 

 tourmaline is " the characteristic mineral of all pegmatites." 

 Although, according to English textbooks, tourmaline is only an 

 occasional constituent of English pegmatites, I wish that when it 

 does therein occur it might be accepted as an original mineral, and 

 not derived from mica. Certainly, if characteristic, it can scarcely, 

 be derived and secondary. 



An interesting subject in connection with superheated water i» 

 the plutonic character of the changes so commonly observed in 

 diabases. In the course of my examination of the Devonshire green 

 schists I examined several of the most altered Devonian diabases, 

 and was much interested to note that one not only met with very 

 active bubbles in the secondary minerals, but also crystal deposits 

 in the fluid inclusions, similar to those in granite, only not markedly 

 cubic. Then in the green schists we find fluid inclusions in the 

 secondary albite granules. To find what were once possibly 

 volcanic tuffs exhibiting full plutonic characteristics was to myself 

 interesting and unexpected ; but when I brought this, to me, novel 

 aspect of superheated water, under the description of hydrothermal 

 metamorphosis, before the British Association at Belfast, a friend 

 kindly informed me that the Committee of Section C did not 

 consider my subject new. 



Dr. Sorby, no doubt, referred to the inclusions in the quartzes of 

 schists, both detrital grains and secondary, in his addresses to the 

 Microscopical and Geological Societies, but I was quite unaware that 

 any work had been done on the inclusions in the secondary quartzes 

 and felspars of green schists and diabases. When one carefully 

 explores one of these quartz grains in an altered diabase, under 

 a high power and strong light, the phenomena seen are strikingly 

 similar to the secondary quartzes seen in some plutonic felspars ; 

 both containing, as they sometimes do, belonites, active bubbles, and 

 deposited crystals. Both results seem due to corrosion by super- 

 heated water charged with minerals and salts, followed by the 

 crystallisation of fresh minerals out of such water. 



Of course, in my own case, these have been only chance 



