150 C F. ROUSSELET ON A SPIRIT-PROOF MICRO-CEMENT. 



of course, also for all watery fluids. It is black, and used like 

 asphalt. The diluting fluid is turpentine or benzole, both of which 

 dissolve it very readily. It sets quickly, but takes two to three 

 weeks to get sufficiently dry for handling the slides. It is very 

 tenacious, and never becomes quite hard and brittle. I usually fix 

 the cover glass of fluid-cells with thickened Miller's cement, and 

 when dry make a ring of Clarke's cement over that. Of course 

 with alcohol mounts Miller's cement cannot be used, and the cell 

 can be made, and must be closed, with Clarke's cement alone. 

 It is best to use the smallest oil-colour sable brush, putting on the 

 cement very gradually and little at a time. The brush can be 

 washed out from time to time in some benzole kept for the purpose 

 in a separate little bottle. 



The composition of the cement is quite unknown to me and is a 

 trade secret. The cement itself can be obtained from Mr. Thos. 

 Bolton, 25, Balsall Heath Koad, Birmingham. 



