364 . SORGHUM. 



chine, introduced in 1843, It consists of a cylindrical vessel, about 

 three feet in diameter, revolving upon an upright shaft. The outer 

 portion of this cylinder is of wrought iron, pierced with numerous 

 small holes. Within this, and lying against it, are one or two screens 

 of wire gauze. This is inclosed within an outer cylinder of iron, of a 

 diameter six or eight inches greater than the revolving drum within. 

 The wire basket (which has an opening at the top for the introduction 

 of the charge, and trap-doors at the bottom for the removal of the sep- 

 arated sugar) is connected by a belt, etc., with an engine, by which it 

 is made to revolve from 1,000 to 1,500 times a minute, thus giving at 

 the circumference a velocity of from two to three miles a minute, for a 

 centrifugal three feet in diameter. The mixer is a long, half cylindri- 

 cal vessel, into which the mass of sugar and molasses from the coolers 

 is emptied, and where (by means of a series of revolving arms, attached 

 to a shaft running lengthwise in the mixer) the contents are stirred into 

 a homogeneous mass. From this vessel (which, for convenience, is 

 placed directly over, and discharges through a sliding valve its con- 

 tents into the centrifugal) a charge is introduced after the centrifugal 

 is set in motion, but before it has attained its maximum velocity. The 

 centrifugal force distributes the mass equally over the gauze periphery, 

 and the molasses forced through is caught by the outer drum, and col- 

 lected in a receiving tank placed below. So soon as the molasses has 

 been separated, a spray of water is thrown upon the surface of the 

 sugar, and the residual molasses is thus removed. A jet of steam is 

 sometimes introduced upon the outside of the perforated drum, 

 to aid in the ready removal of the molasses; and, after the washing, 

 hot air is drawn in upon the sugar to dry it. Ordinarily from five to 

 fifteen minutes suffices to purge one charge, although the character of 

 the mush sugar introduced is sometimes such, that a far longer time 

 is necessary. 



Vacuum pan sugars, being made up of larger crystals, are far more 

 easily purged than the softer, finer grained, open pan sugars, and the 

 purging of such coarse grained sugars is accompanied with less loss of 

 sugar. The injurious effect of false grain is here manifest, since it tends 

 to block up the meshes of the gauze, and thus prevent the expulsion 

 of the molasses. The treatment of water, therefore, either in the 

 mixer or in the centrifugal, for the purpose of dissolving these minute 

 crystals of sugar is rendered necessary. 



