754 PROCEEDINGS OF THE SOCIETY. 



to get rid of. The reason of this was that the surface of glass, how- 

 ever well polished, was not mathematically true, the most highly- 

 polished surface having its face covered with very fine lines, and 

 these not all running in th.e same direction. In fact, if marks were 

 made upon a piece of glass with glycerin or turpentine the traces of 

 them could be distinctly seen after the glass had been well rubbed. 

 The first thing therefore to do was to get a perfectly clean slip, and 

 having put it upon the turntable, to make a ring of Canada balsam 

 dissolved in benzole. The next thing was to get a perfectly clean 

 cover-glass, and in order to hold this conveniently he liad found it an 

 excellent plan to mould a small piece of beeswax into a semicircular 

 form having about the diameter of the cover, which if slightly pressed 

 upon the upper side of the cover adhered to it sufficiently to form a 

 kind of handle by which it could be lifted, and if it were turned 

 upside down it would stand upon the corner of the table until it was 

 wanted for use. A ring of the balsam was then put upon the under 

 side of the cover-glass of the same size as that upon the glass slip. 

 The next step was to select the object, and he had found that the 

 most convenient things in which, to keep stained objects were the 

 small china saucers which were to be bought at the artists' colour 

 shops ; they were much better than watch-glasses. He then took up 

 a small drop of glycerin and put it in the ring of balsam which had 

 been made on the slide (and for this purpose he had found nothing 

 better than the ivory handle of a small dissecting-knife), and then 

 the object was placed on the slide. In doing this he had found 

 nothing so useful as a watchmaker's eye-glass, and to save the 

 inconvenience of having to take it up every time it was wanted he 

 had it fastened round his head with a piece of elastic web, and when 

 not in use it was pushed up upon the forehead. Having placed the 

 object on the slide in proper position it was well to remove all 

 superfluous glycerin, and the best way to do this was with a small 

 sable brush, sucking off the fluid when the brush was full. Another 

 drop of glycerin was then put upon the under side of the cover-glass, 

 which was then placed in position on the slide ; the two rings of 

 balsam were slightly pressed together; they adhered immediately, 

 and the thing was done. A small amount of practice would enable 

 any one to judge exactly how much glycerin was required to fill the 

 space ; but if it happened that too much had been used it would force 

 a small channel for itself and squeeze out through the balsam, which 

 would afterwards close together again quite tightly. The only thing 

 remaining to be done was to put on a coating of Hollis's glue to 

 prevent the balsam from setting, and by adopting this system it 

 would be found that the cover could be pressed down just as much 

 as was required. The usual process was to smear the glass with 

 glycerin first, and then of course the cement would not adhere 

 properly and the result was leakage. Mr. Cheshire further illus- 

 trated his meaning by drawings upon the blackboard and by the 

 exhibition of specimens which were handed round for inspection. 



Mr. J. W. Groves said that Mr. Cheshire's first statement was 

 that delicate structures and cells could not be seen in balsam-mounted 



