CEMENTS. 



The number of cements and varnishes is so numerous that one 

 is at a loss to know just what is best to use, but the general char- 

 acters of some of the more common ones will be brieflly noted. 



Gold Size. 



This cement can be secured of dealers in microscopical sup- 

 plies and is certainly to be well recommended. If used for balsam 

 mounts, it is best to first ring the cover glass with a coat of shellac. 



Shellac. 



Shellac is certainly very convenient and seems to be quite dur- 

 able. It is prepared by dissolving solid shellac in alcohol until the 

 solution is of a medium oily consistency. A little aniline dye can 

 be added to color the mixture to one's fancy, also a few di'ops of 

 oil should be used to prevent the cement from cracking. The mix- 

 ture is applied, as are all sealing mixtures, with a small brush and, 

 preferably, by the use of a turn-table. 



Ball Cement and Asphalt Varnish. 



These are among the very best of cements and can be obtained 

 from the regular dealers in supplies. 



White Zinc Cement. 



This cement is much used by microscopists for making cells. 

 It is very hard and often shows a tendency to crack. 



Many very good cements are on sale by reliable dealers, and 

 one has but to convince himself of the relative merits of a few of 

 the more important ones, when he will be able to settle upon some 

 special one well adapted to his purpose. 



