CHAPTER XX. 231 



pp. 229 30). Venice turpentine, or common resinous turpentine, 

 evaporated by heat until brittle on cooling. It is used for closing 

 glycerin mounts in the following manner : Square covers are used, 

 and superfluous glycerin is cleaned away from the edges in the 

 usual way. The cement is then put on with a piece of wire vent at 

 right angles ; the short arm of the wire should be just the length of 

 the side of the cover-glass. The wire is heated in a spirit lamp, 

 plunged into the cement, some of which adheres to it, and then 

 brought down flat upon the slide at the margin of the cover. The 

 turpentine distributes itself evenly along the side of the cover, and 

 hardens immediately, so that the slide may be cleaned as soon as 

 the four sides are finished. It is claimed for this cement that it is 

 perfectly secure and never runs in. It sets hard in a few seconds. 



468. APATHY'S Cement for Glycerin Mounts (Zeit. wiss. MiL, vi, 

 1889, p. 171). Equal parts of hard (60 C. melting-point) paraffin 

 and Canada balsam. Heat together in a porcelain capsule until the 

 mass takes on a golden tint and no longer emits vapours of turpen- 

 tine. Used by warming and applying with a glass rod or brass 

 spatula. One application is enough. Does not run in, and never 

 cracks. 



469. Canada Balsam, or Damar. Cells are sometimes made with 

 these. They are elegant, but in my experience are not reliable for 

 permanent mounts. 



470. Tolu Balsam Cement (CARNOY'S Biol Cell, p. 129). Tolu 

 balsam, 2 parts, Canada balsam 1, saturated solution of shellac in 

 chloroform, 2 parts. Add enough chloroform to bring the mixture 

 to a syrupy consistence. Carnoy finds this cement superior to all 

 others. 



471. For the cements of WARD, BELL and CLARKE and for 

 KRONIG'S Colophonium and Wax, Marine Glue, Amber and Copal, 

 and Sealing Wax Varnish, see last edition. 



