106 METHODS OF MICROSCOPICAL RESEARCH. 



it shall be entirely discarded for all purposes of 

 mounting, and used only as a cement, in which 

 character it has its uses, and especially it is good 

 for " ringing " glycerine jelly and glycerine 

 " mounts " before the application of the shellac 

 varnish, and the finishing white zinc cement. 

 Dammar varnish is made thus : 



1^ Indian Gum Dammar, 4 drachms. 



Benzol (best) 8 (fluid). 



Let it stand for two or three days, then pour off 

 the super-natant liquid, and add thereto 1 drachm 

 of spirits of turpentine. Filter if necessary. 



Bell's Cement. 1 This is a thoroughly reliable 

 cement for many purposes ; it is easy to use, as it 

 flows readily from the brush and hardens rapidly. 

 Shallow cells can be made with it, and it may be 

 used for sealing up preparations mounted in fluids, 

 glycerine, or glycerine jelly, in place of shellac 

 varnish, the cover being previously " ringed" with 

 the following : 



GELATINE CEMENT. (Marsh's formula.) 



Soak half an ounce of gelatine in water until it is 

 thoroughly soft. Pour off nearly all the water, and 

 melt the gelatine in a hot water bath ; add 3 or 4 

 minims of creasote and keep it in a capped bottle. 

 It must be used warm, it sets very quickly, and may 

 be followed by Bell's cement, or shellac varnish^ 

 and the slides be finished with white zinc cement. 



1 This cement must be purchased from its makers, Messrs. 

 J. Bell & Co., 338, Oxford Street, London, or from the 

 opticians ; its formula being a secret. 



