190 PRACTICAL HISTOLOGY. 



cover this with white zinc cement. The latter gives an 

 elegant finish to the preparation, and is at the same time an 

 excellent varnish. Shadbolt's turn-table (Fig. 63) is often 

 employed in applying the varnish. Glycerine is apt to ooze 

 through the varnish after a time ; when this happens, run a 

 stream of cold water over the preparation, then dry and 

 paint on a fresh layer of zinc cement. 



359. Mode of keeping Preparations. The slides 

 should lie upon the back, not upon the edge. All prepara- 

 tions should be carefully labelled. The things shown should 

 be mentioned, the date, and the name of the mounting fluid 

 ought also to be stated. Never keep a bad preparation, and 

 don't attempt to preserve everything. 



