CEMENTS AND VAliNISllKS. 2,^0 



an extreme tenacity. That used by liim may be obtained 

 from Griibler & Hollborn. 



476. Amber and Copal Varnieh (He's^demheich, Zeit. wiss. Mih., 

 1885, p. 338). — Extremely complicated. 



477. Shellac Varnish (Bbalb, p. 28). — A thick solution of sliellac 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 Lecome brittle and to lose its hold upon glass 

 after a time. 



479. Tolu Balsam Cement (Caeno^'s Biul. 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. 



