1900] MICROSCOPICAL JOURNAL. 325 



estimated, the lamp lighted and placed beneath the brass 

 table. In about a minute the (glycerine jelly will begin to 

 melt, and the lamp is promptly removed. Any air-bub- 

 bles should be skimmed off before the cover-glass is put 

 on ; and as the glycerine jelly will only solidify again by 

 cooling, there is no need to hu"rry the process. After an 

 examination, the cover-glass may be lowered carefully in 

 its place, a clip slipped on, and the whole slideput aside 

 for half a dozen hours or more to set. The excess of jelly 

 around the cover-glass may then be removed by means of 

 a penknife, and the whole slide cleaned by dipping in a 

 saucer of water or holding under a running tap, finally 

 polishing with a bit of rag. Glycerine jelly is often used 

 when mounting in built-up cells, but before doing this it 

 is advisable to run a wetted camel's-hair brush round the 

 cell to make sure that no air-bubbles will cling to the 

 side or bottom. Pure glycerine is not often used for other 

 than temporary mounts, as it will not set ; but a mixture 

 of glycerine and gum arable, with a little arsenious acid, 

 known as Farrant's solution, is often used, especially in 

 histological preparations, as it dries at the edges. It is 

 best bought, as home-made preparations are not always 

 satisfactory. Glycerine acts as a solvent for carbonate 

 of lime, and should, therefore, not be used for objects of 

 a calcareous nature. 



Ringing. — Canada balsam slides do not necessarily 

 need ringing, though our own practice is to ring all our 

 slides, but glycerine slides should be finished off with a 

 couple of rings of gold-size. The process is very similar 

 to that of cell-making. The slide is centred upon the 

 turn-table, taking care to centre by means of the cover- 

 glass and not by the slide, and a ring of gold-size run 

 round the edge of the cover-glass. Care must he taken to 

 just cover the edge of the latter, and not to overlap the 

 slide too widely. Beginners generally take up too mucli 

 gold-size in the brunh. A neat ring is made by attentiuu 



