CEMENTS AND VARNISHES. 253 



an extreme tenacity. That used by liini may be obtained 

 from Griibler & Hollborn. 



476. Amber and Copal Varnish (HEYDENREICH, Zeit. wiss. Mil:., 

 1885, p. 338). Extremely complicated. 



477. Shellac Varnish (BEALE, p. 28). A thick solution of shellac in 

 alcohol. The Micro. Dictionary says that the addition of 20 drops of 

 castor oil to the ounce is an improvement. Untrustworthy. 



478. Sealing-Wax Varnish (Micro. Diet., " Cements"). Add 

 enough spirit of wine to cover coarsely powdered sealing-wax, and digest 

 at a gentle heat. This should only be used as a varnish, never as a 

 cement, as it is apt to become brittle and to lose its hold upon glass 

 after a time. 



479. Tolu Balsam Cement (CAENOY'S Biol. Cell.,, p. 129).- 

 Tolu balsam, 2 parts, Canada balsam 1, saturated solution 

 of shellac in chloroform,, 2 parts. Add enough chloroform 

 to bring the mixture to a syrupy consistence. Carnoy 

 finds this cement superior to all others. 



