852 



RECORD 0!f current RESEARCHES RELATING TO 



In a few days the mass will have set hard, and can be removed from 

 the mould, ground, and polished like a natural rock, as it possesses 

 great tenacity. On examination under the Microscope, the sections 

 of mineral that it contains are easily distinguished in the midst of 

 the surrounding opaque material. 



Dr. Matthews's Machine for Cutting Hard Sections.— In the 

 previous volume * we gave a preliminary account of this machine, 

 and now add the full description, with woodcuts. Fig. 77 being a plan 

 view, and Fig. 78 a side elevation. 



Fig. 77. 



Fig. 78. 



The metal stage-plate A is supported upon four pillars B B, and 

 is mounted upon a base-board C. On the upper side of the stage A 



* See tliis Journal, ii. (1870) p. 957. 



