256 ECONOMIC BOTANY. 



back of the mother insect, and bore a hole through the 

 resin through which to escape. If it is desired especially 

 to obtain lac-dye (for dyeing silk and wool), the resin must 

 be collected before the young insects hatch out, since the 

 coloring matter is contained in the ovary of the females, 

 and but little of it remains after the young develop. To 

 obtain the largest amount of both dye-stuff and resin, the 

 twigs are collected in June and November. "When the resin 

 is melted, strained through thick canvas, and spread out in 

 thin layers, it forms shell-lac, the form most commonly 

 found in commerce. It is tasteless, odorless, and varies in 

 color from light to deep-brown. Its important constituents 

 are resin, lac-dye, and waxy substances. Lac is the prin- 

 cipal ingredient in sealing-wax, and forms the base of 

 valuable varnishes. It is used besides in various cements, 

 in the manufacture of felt, etc. It can be bleached, and 

 will take delicate shades of color ; dyed a golden color it is 

 much used in the East Indies for working into personal 

 adornments. 



225, The resinous substance Copal, somewhat resem- 

 bling Amber, comes from very many different plants. The 

 East African Copal comes from species of TraeJiilobium, 

 of the Pulse family (Legwninosm). This is the hardest, 

 and considered the best. It is tasteless and odorless. The 

 surface is opaque, but within it is clear and transparent. 

 The external crust is removed by washing, when the sur- 

 face is seen to be faceted. The West African Copal is a 

 " recent fossil," found in the sandy or clayey soil sometimes 

 at a depth of ten feet. It is supposed to come from Oid- 

 bourtia copallifera. The New Zealand Copal flows spon- 

 taneously from the twigs and stems of Dammara australia 

 (family Coniferai). It hardens quickly, is at first milky 



