The Microscope. 43 



and a glass plate one and three-quarter inches in diameter fitted 

 to the well of the stage. The jointed arm carrjang the lenses is 

 moved by a sliding rod, giving fine and accurate movement. 

 The stand has plane mirror with complete adjustments, two 

 sinole lenses of one inch and three-quarter inch focus, which 

 may be combined to form a two-third inch, the whole instru- 

 ment being packed in a neat walnut case, with drawer and 

 handle. 



ELEMENTARY MICROSOPICAL MOUNTING— TY. 



DR. A. M. WEBSTER. 

 SHELLAC CEMENT. 



WITHOUT exception this is the best, the most convenient, 

 the easiest to make and to keep, and the most satisfactory 

 and trustworthy cement that the microscopist can use. It may 

 be made by any one, and used successfully by the least skillful, 

 without much worr}^ as to the result. It is an indispensible 

 article to the microscopist. With it he may build up cells, 

 fasten on cover glasses, attach deep tin rings to the slip, patch 

 up old mounts, and use it as a kind of universal panacea for 

 preparations microscopical. Its tendency toward that dreaded 

 characteristic of some other cements, running under the cover, 

 is so slight that it may be almost disregarded, unless, of course, 

 the cement be used too thin, or unless the user be careless. Every 

 cement will run under, if allowed to do so ; the laws of capillary 

 attraction are never suspended ; the microscopist must act so as 

 to prevent them from doing his slides an injury. With shellac 

 he has little to fear with ordinary caution. 



The cement is simply shellac dissolved in alcohol. Put the 

 gum in a wide mouthed bottle, fill it with alcohol, and leave 

 it to dissolve. If the solution is too thick add alcohol till it is 

 properly thinned ; if too thin, leave the cork out, with the bot- 

 tle in a dust-free air, and evaporation will do the rest. It should 

 be thin enough to flow freely from the brush and to remain on 

 the glass where the brush leaves it, without running in an irreg- 

 ular way over the surface, as it will run if too thin. When dry 

 it makes a yellowish brown ring that is not unpleasing, but 

 which ma}' be colored by adding a little of any of the anilines 

 dissolved in alcohol. These coloring matters, however, are 



