iSgS-l NEW-YORK MICROSCOPICAL SOCIETY. 159 



SO fast that it can be mounted in glycerine and will always keep 

 its place. The albumen is transparent except when too much 

 is used. 



" For mounting objects which require a high refractive index, 

 I consider Prof. Smith's new medium preferable to any other 

 yet found. Even when diluted to a fluid consistency, it will not 

 evaporate, and is easily confined by white-zinc cement. Whether 

 it is permanent or not, time only can determine. Prof. Smith 

 does not give his formula, and his reason for not doing so is 

 that ' he does not wish to be premature in putting before the 

 world another material that may prove a failure.' In the April 

 Number of the " Journal of the Royal Microscopical Society " 

 he is, I notice, taken to task for keeping secret the composition of 

 his deep-yellow medium (2.4 refractive index). My impression 

 is that he did give to his friends the formula of this prepara- 

 tion. I have known Prof. Smith many years, and I am sure 

 that, if he should make an important discovery of this kind, he 

 would not retain it as a trade secret." 



