578 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



when completed the other side was a simple repetition of careful 

 grinding on a water-of-Ayr stone, just as an ordinary rock section 

 would be treated, only with more care when the critical point was 

 approached. 



Finally, Dr. C. H. Griffith, one of the editors of the ' Micrographic 

 Dictionary,' says he is " greatly amused at the discussion," and 

 suspects the writers " have been experimenting with the refractory 

 anthracite coal too common in our coal-scuttles ; but this being 

 nearly all mineral matter, of course, does not yield to the action of 

 the potash. Neither would it show much if so cut. They remind 

 me of a former sapient microscope pupil of mine, who took to himself 

 much credit for soaking a nail from the ' Victory,' in the hope of 

 making a section of it lor the Microscope to show the structure. The 

 coal for which this process is recommended, and which yields the 

 best objects, is that which is more of a lignite character, and when so 

 treated and digested with heat, is cut readily. To my own knowledge 

 Professor Henfrey cut hundreds of sections in this manner." 



Sections of Mica-schist.* — In a paper describing the methods he 

 originally adopted for rock sections, Dr. H. C. Sorby says that it is 

 possible to prepare thin sections of mica-schist perpendicular to the 

 foliation, although it is so friable that at first sight it appears im- 

 possible. Having got a fairly thick portion and reduced it to about 

 ^ inch, it must be wetted well with turpentine so that it may penetrate 

 into the pores of the rock, and then covered over with Canada balsam 

 and kept hot inside the fender. The balsam penetrates into the loose 

 material, and thus supplies artificially what nature has failed to 

 supply in not having hardened it sufficiently by infiltered quartz. 

 It is well to repeat the process after a little time. 



By this means the weak points of the mica-schist and the planes 

 of discontinuity are filled with hard Canada balsam so as to make it 

 thoroughly hard throughout, and enable it to be rubbed down and the 

 section left of the desired thickness. 



Paper Cells.f — Mr. W. H. Walmsley, in an article (the third of a 

 series) on Dry Mounting, considers that the remedy for the appearance 

 of moisture in cells is to be found in " sacrificing artistic cells of wax, 

 with their pretty coloured rings of varnish, and being content with 

 those of humbler and far more useful qualities. Paper, from which 

 such dissimilar articles are now manufactured as love-letters and car- 

 wheels, is our friend in need in this emergency, — not sized, or 

 glazed, or calendered, but soft, porous paper of various thicknesses to 

 suit our needs ; a thick blotting pad being exceedingly useful for cells 

 containing objects sufficiently thick to require such a depth." 



Wax Cells.! — Mr. T. Whitelegge proposes " a very simple 

 method of making wax cells. A piece of glass tubing is first drawn 

 out to a point so as to form a pipette, and this is filled with melted 



* North. Microscopist, ii. (1882) pp. 134-5. Cf. also Mr. Kutley's process, 

 this Journal, iii. (1880) p. 849. 



t ' The Microscope,' ii. (1882) pp. 1-8. 

 % North. Microscopist, ii. (1882) p. 194. 



