The Mickoscope. 



251 



To carry out this method only two articles in addition to those 

 usually possessed by microscopists are required, one being the ring 

 with an internal flange at the top and an external flange at the bot- 



tom ; the other, a heating tool consisting of a ring of brass attached 

 to a suitable handle. 



The rings, of which the walls of the cells are formed, are spun 

 or stamped from disks of Britannia metal, sheet brass, or other sheet 

 metal, with a narrow internal flange or fillet at the top for receiving 



the cover-glass, and a wider external flange at the bottom for attach- 

 ment to the slide. 



The rings vary in depth according to the depth of cell required; 

 the under surface of each ring is coated with thick shellac-varnish 

 and allowed to dry thoroughly. When the varnish is dry and hard, 

 a clean cover-glass is droj^ped into each ring, and the ring is placed 

 bottom upward on the mounting- stand and heated until the shellac 

 melts and thoroughly covers the edge of the cover- glass; the ring is 



