SECTION THREE 



Cedarwood oils for immersion can be thinned, if desired, by 

 stirring in a little cedarwood oil for clearing. 



COVERLAC 



A clear, colourless, synthetic neutral lacquer, refractive index 

 1-518, which may be used instead of mounting media and cover- 

 glasses for smears and sections. It is not claimed that Coverlac 

 ensures a uniformly flat optical surface; indeed this is impossible 

 without the usual mounting medium and coverglass, but except 

 for very critical work, Coverlac offers an economical means of 

 covering smears and sections. Preparations are stained, dehy- 

 drated and cleared as usual; excess liquid is removed, and the back 

 of the slides dried thoroughly: Coverlac is then dropped on to 

 the slides; which should be placed on a flat surface, to form a 

 protective film. The slides are then placed in a drawer, or covered 

 in a similar manner, to protect them from dust overnight, after 

 which the coating of Coverlac may be hardened off in an oven 

 overnight and during the next day. 



FLUOROIL 



(Edward Gurr) 



Refractive index i*5i5 



This is a clear, colourless, non-sticky, non-drying, synthetic 

 immersion oil, which does not fluoresce in ultra-violet light, a 

 property which renders it suitable for fluorescence microscopy, 

 for which this oil is intended. 



The oil is miscible with xylol and benzene. 



GELATIN ALCOHOL ADHESIVE 



(M. A. Albrecht) 

 For attaching frozen sections to slides 



Sprinkle i -5 gm. of powdered gelatin on to the surface of 

 120 ml. of warm water (about 50-55° C.) in a beaker, then after 



527 



