140 Prominent Yorkshire Workers — Henry Cliflon Sorhy. 



minerals in these rocks crystallised out from a solvent in the 

 state of g-lassy fusion. ' This fact at once settled the question, 

 so long- disputed between the Wernerians and Huttonians.' 

 These inclusions in minerals indicated whether the rocks had 

 been formed by the action of water or of fusion or by the two 

 combined under pressure. 



in 1858 he read a paper to the Geolog-ical Society- on ' The 

 Microscopical Structure of Crystals, indicating the orig-in of 

 minerals and rocks.' The late Leonard Horner, the onlv 

 sur\i\ ing original Fellow, was in the chair, and after the paper 

 was read stated that he had been a member of the Society ever 

 since its foundation, but ' did not remember an)' paper having 

 been read which drew so largely on their credulity,' the facts 

 being so new and remarkable ! Sorby was also the first to 

 point out that certain minerals contained liquid carbonic acid, 

 and described its striking properties. 



The microscopical character of loose sand-grains then occu- 

 pied his thought, and the}' were found to possess features having 

 an important bearing upon the origin of certain sandstone 

 rocks. Next followed his explanation of the so-called ' crystal- 

 line sands,' which contain crystals of quartz due to the deposition 

 of crystalline quartz around ordinary grains of sand which had 

 acted as nuclei. A study of pseudomorphs — crystals in the 

 form of one mineral, but with the chemical composition of 

 another — resulted in many important discoveries. About i860 

 he made a whole series of artificial pseudomorphs by the action 

 of cold or highly-heated solutions. It was demonstrated that 

 certain rocks, such as the Cleveland ironstone, ' were originally 

 composed of carbonate of lime, but have been altered to 

 carbonate of iron, the carbonate of lime having been dissolved, 

 and carbonate of iron derived from the associated strata 

 deposited in its place.'* 



Following on this line of research upon the structure of 

 rocks, he eventually proved that there is a direct correlation 

 between mechanical pressure and certain kinds of chemical 

 action, and gave the results of his work in a paper to the Royal 

 Society, which formed the Bakerian Lecture for 1863. 



I^xperiments on the freezing point of water and on the ex- 

 pansion of water and saline solutions at high temperatures 



* In connection witli tlic ("inishofouuli nicclini;' ot" the N'orksliii-c 

 Xatmvilists' Union, to he lu-lil in Antriisl next, the cjiicstion of the origin 

 of the Clevehmd Ifonslone is to he liisciissed. Dr. Sorhy has kindly 

 ajCreed to contribute a paper on the subject on that occasion. 



N.itiirall'l 



