

40 GOODYEAR ON GUM-ELASTIC. 



" According to Franke, the constituents of stick lac are, resin, 

 65.7; substance of the lac, 28.3; coloring matter, 0.6. 



" Seed lac. When the resinous concretion is taken off the 

 twigs, coarsely pounded and triturated with water in a mortar, 

 the greater part of the coloring matter is dissolved, and the 

 granular portion which remains, being dried in the sun, consti- 

 tutes seed lac. It contains, of course, less coloring matter than 

 the stick lac, and is much less soluble. John found in 100 parts 

 of it, resin, 66.7; wax, 1.7 ; matter of the lac, 16.7; bitter bal- 

 samic matter, 2.5 ; coloring matter, 3.9 ; dun yellow extract, 

 0.4; envelopes of insects, 2.1 ; laccic acid, 0.0; salts of potash 

 and lime, 1.0; earths, 6.6 ; loss, 4.2. 



" In India, the seed lac is put into oblong bags of cotton cloth, 

 which are held over a charcoal fire by a man at each end, and 

 as soon as it begins to melt, the bag is twisted so as to strain the 

 liquified resin through its substance, and to make it drop upon 

 some smooth stems of the banyan tree, (Musa paridisa.) In this 

 way the resin spreads into thin plates, and constitutes the sub- 

 stance know^i in commerce by the name of shellac. 



" The Pegu stick lac, being very dark colored, furnishes a 

 shellac of a corresponding deep hue, and, therefore, of inferior 

 value. The palest and finest shellac is brought from the 

 Northern Circas. It contains very little coloring matter. A 

 stick lac of an intermediate quality is brought from the Mysore 

 country, which yields a brilliant lac-dye and a good shellac. 



It is but recently that gum-shellac has been used in the man- 

 ufacture of the vulcanized compounds. Thus far it appears to 

 be indispensable in one of the hard compounds, and in many 

 of the fabrics, it is preferable to all other inferior gums and 

 resins, on account of the more agreeable odor of the fabrics. 

 In these it is mixed in about the proportion of one part shellac 

 to three parts caoutchouc. 



