772 EXTRACTION OF TDRPEXTIXE AND ROSIN. 



engine into an elevated reservoir ; it is then used again for cooling 

 the turpentine. The engine also drives steam into the distilling 

 retort. 



The liquid colophany, after distillation of the turpentine, 

 is allowed to flow from the base of the retort by removing a 

 wooden plug stamped with clay. It runs into a straining tank, 

 passing over a very fine copper wire-sieve, which catches most 

 of the impurities it has still retained ; the rest falls to tlie 

 base of the straining tank, in the form of a black deposit 

 resembling pitch. The straining tank has a tap placed about 

 half-way down, through which the liquid colophany passes during 

 autumn into another vat, from which it is ladled into large casks 

 containing about 800 lbs. 



During summer, how^ever, after a sample has been taken 

 out in a tin mould, the rest of the colophany is at once ladled 

 from the straining tank into buckets ; it is then carried to an 

 open court-yard, where it is poured into open shallow metal 

 pans about two inches deep and slightly smaller in diameter 

 than the casks in which it is finally packed for sale. It there 

 cools into cakes which are exposed to the sun till sufficiently 

 bleached ; they are then placed, one above the other, in the casks 

 and eventually unite into a single mass. 



Great attention is paid to uniformity of colour in each cask, 

 the sample shown to the purchaser being the worst coloured 

 in the cask. The colophany goes into four main classes, for 

 spring, summer, autumn and winter, the first being lightest 

 coloured and most transparent ; and the last, made chiefly of 

 harraa, being darkest. The tints vary from very pale transparent 

 yellow to dark amber. When nearly black it is termed hrais. 

 Great stress is laid on transparency, denoting purity of the 

 samples, as well as on their light colour. The dark amber- 

 coloured colophany is worth only one third the value of the 

 palest l)rand, the prices varying from 4s. to 12s. 9d. per 100 lbs. 



Besides the main classes of colophany, the commercial grades 

 range from A. the darkest, to N, extra pale, superior to which 

 are \V. window- glass and W. W. water-white. These are 

 American brands which have been adopted in France. 



A barrel of 520 lbs. of crude turpentine yields 3G4 lbs. 

 colophany, 110 lbs. oil of turpentine luid 4G lbs. refuse. The 



