36 



BULLETIN 314, U. S. DEPARTMENT OF AGRICULTURE. 



The extractor shown in figure 18 was designed upon lines suggested 

 by an examination of machines in use by A. E. Schutte and C. N. 

 Forrest. It consists of a one-fifth-horsepower 1 ; 100 revolutions per 

 minute vertical-shaft electric motor a, with the shaft projecting into 

 the cylindrical copper box h, the bottom of which is so inclined as to 

 drain to the spout c. A three-sixteenths-inch circular brass plate 9§ 

 inches in diameter is shown in d, and upon this rests the sheet-iron 

 bowl e, which is 8J inches in diameter by 2^ inches high, and has a 2- 

 inch circular hole in the top. Fastened to the inner side of the bowl is 



the brass cup/, having a circle of one- 

 eighth-inch holes for the admission of 

 the solvent, and terminating in the 

 hollow axle, which fits snugly through 

 a hole at the center of the brass plate. 

 The bowl may be drawn firmly against 

 a felt-paper ring g, three-fourths inch 

 wide, by means of the 2J-inch milled 

 nut Tb, for which the hollow axle is 

 threaded for a distance of three- 

 fourths inch directly below the upper 

 surface of the plate. The axle fits snugly over 

 the shaft of the motor, to which it is locked 

 by a slot and cross pin i. 



The aggregate is prepared for analysis by 

 heating it in an enamel-ware pan on the hot 

 plate until it is sufficiently soft to be thor- 

 oughly disintegrated by means of a large 

 spoon. Care must be taken, however, that 

 the individual particles are not crushed. If 

 a section of pavement is under examination, 

 a piece weighing somewhat over 1 kilogram may be cut off with 

 hammer and chisel. The disintegrated aggregate is then allowed 

 to cool, after which a sufficient amount is taken to yield on ex- 

 traction from 50 to 60 grams of bitumen. It is placed in the 

 iron bowl and a ring three-fourths of an inch wide, cut from the 

 felt paper, is fitted on the rim, after which the brass plate is placed 

 in position and drawn down tightly by means of the milled nut. If 

 the bitumen is to be recovered and examined, the felt ring should be 

 previously treated in the empty extractor with a couple of charges 

 of carbon disulphide in order to remove any small amount of grease 

 or resin that may be present, although a proper grade of felt should 

 be practically free from such products. The bowl is now placed on 

 the motor shaft and the slot and pin are carefully locked. An empty 

 bottle is placed under the spout and 150 cubic centimeters of carbon 



Fig. 18. — Centrifuge extractor 

 (Reeve type). 



