PROCESS OF MANUFACTURE. 771 



into a second vat. The operation of beating and filtering goes 

 on a day in advance of the distillation, so that three vats are 

 required, No. 1 vat being always used for boiling and the other 

 two vats, alternately, as reservoirs from which the resin is ladled 

 into a small tank from which it is passed through a tap to the 

 retort shown in fig. 340. 



This is the method employed late in autumn, when the 

 resin contains many impurities. Earlier in the year, it is 

 passed directly from vat No. 1 to No. 2, a retort in which it 

 is distilled, the arrangement of the vats then being as shewn 

 in fig. 340. 



The resin in the retort is heated to a temperature of about 

 185° F., steam (by the use of which 30% more turpentine is 



Siphon 



(After Heaile. ) 



obtained) being admitted through a pipe. From this retort, 

 vapour of the oil of turpentine and water-vapour pass through 

 a coil of tubing into a cooling tank, where they are condensed ; 

 they are then drawn off into a smaller tank, the water remaining 

 below with the turpentine floating on it, owing to the lower 

 specific gravity of the latter. The oil of turpentine is then run 

 through an over-flow pipe into a zinc vessel mounted on a 

 truck, and conveyed by means of a tramway to the turpentine 

 shed, where it is pumped into large metal tanks, measuring 

 10 feet by 6 feet by 6 feet, from which it is drawn, as required 

 for sale, into old Spanish wine-casks. No system of purifying 

 is in practice, and it is sold just as it issues from the still. 



The water, which is removed by a siphon from below the 

 turpentine, passes after use through a series of shallow open 

 tanks in a court-yard, from which it is pumped by a small steam 



