14 THE AMERICAN MONTHLY [Jan 



as gum-water. Simply place the best shellac you can ob- 

 tain in a large bottle not more than half or three-quarters 

 full with strong alchohol, shake up frequently until the 

 lac is dissolved : it is best made at ordinary temperature. 

 The result is a turbid mixture. If you make about half 

 a pint, add a teaspoonful of red lead to the solution and 

 shake it up; in a few days the red lead will have carried 

 down all the thick matter, leaving a fine clear varnish, 

 which decant. 



"Shellac varnish resists glycerine and its compounds, 

 but has the defect of being brittle, unlike gold size, which 

 retains considerable toughness after the lapse of many 

 years. For ringing balsam mounts I add twenty drops 

 of castor oil to 1 oz. shellac varnish, but for other pur- 

 poses use it pure. 



"The principle of securely closing a cell containing 

 fluid is to use first a varnish not affected by the medium, 

 irrespective of its brittleness, and when the fluid is se- 

 cure, use with a reliable varnish for security. 



"My practice with glycerine and compounds is this, 

 which will show what I mean. When I have put on the 

 cover I clear away with a fine pipette and suction as much 

 fluid as I can, absorbing the rest carefully with scraps of 

 blotting paper ; I then ring with a solution of damar in 

 benzole, a weak and bad varnish, but which has the use- 

 ful property of sticking to wet glass. When dry I wash 

 under a tap so as to remove all traces of glycerine; this 

 is important, as no sound joint can be made so long as 

 glycerine or other fluid that persistently adheres to glass 

 is in the way. I follow with a ring of shellac (pure), when 

 dry wash again and then give two or three coats of shel- 

 lac, washing if there is any doubt about the joint being 

 perfectly clean. The glycerine is now secure, and the 

 mount is then secured with gold size, which should be 

 laid on thinly and at least six coats. I have never found 

 a slide to leak. If gold size had been used at once the 



