230 



PnODUCTS DERIVED PROM TDBPENTINES. 



thereon, are placed in a brick furnace {Fig. 71). Fire is kindled 



Fig. 71. 



at the top and the resinous matters 

 escape into the cooler c, the ashes 

 being removed through a passage 

 existing at a. What passes into the 

 cooler consists of two portions, one of 

 them a nearly solid one, which sinks 

 to the bottom and is black pitch. It 

 is an opaque, black substance, with 

 conchoidal fracture, peculiar unplea- 

 sant odour, scarcely perceptible fla- 

 vour, dissolving in the same men- 

 strua as tar, and capable of being 



_., , J! t „ „f i,i„„T, kneaded when softened by the heat 



Kiln for manufacture of blach J 



pitch. of the hand. 



In works having the modern improvements, the only residues 

 are those left in the boiler {Fig. 70, 6). These residues are filtered 

 through mats and afford a little more crude turpentine. The mats, 

 with all the impurities, are then placed in the apparatus shown in 

 Fig. 72, which consists of a double-lined trough, with steam cir- 

 culating in the intermediate 

 ^^' space s s. The residues are 



put on the metallic gauze 

 tray t, and the trough is co- 

 vered to prevent evaporation 

 of the essential oil. Under 

 the influence of the heat, 

 the turpentine falls into the 

 space s p below. It is then 

 distilled in the apparatus re- 

 presented in Fig. 70, and 

 yields a light-coloured pitch, 

 with a little oil. The straw 

 mats are finally treated as 

 in the preceding case and 

 afford black pitch. From 

 the light-coloured pitches is 

 manufactured the common 

 yellow rosin, which is used 

 for sizing the inferior kinds 

 of paper, in soldering metals, 

 and for rendering chips of wood combustible for lighting fires. The 

 pitch used for caulking is one of the light-coloured kinds, but may 



Apparatvs for clearing filtration residues 

 in malting light-oolamred pitches. 



