EschihUed at the Nottingham Meeting. 97 
themselves separated, according to their densities, into lighter 
and heavier samples. No sifting can accomplish this, because 
the middlings and the bi-an are often of the same sizes, although 
differing in specific gravity. 
The work is usually done by a combination of silk riddles, 
and a current of air, produced by an exhausting fan. The 
former are given a do\vuward beat by the action of a pair of 
cams, which, compressing rubber springs at the corners of the 
riddle frame, cause the riddles to rise and strike against a 
stationary buffer, the sudden stopping of the sieves throwing 
the middlings into suspension, and enabling the exhaust to act 
with the greatest effect upon them. The air current, which 
sweeps upwards through the silks, carries the lightest particles 
Fig. 3. — Emil IVeis' Patent Middlings Purifier. 
away altogether, but is not powerful enough to prfevent the heavy 
granules of semolina from falling throngh the riddles. 
In the machine recently invented by Mr. Emil Weis, the 
exhaust fan is abolished altogether, and the necessary current of 
air is produced by a loose, air-tight cloth covering the riddles, 
one end of which is kept in undulating motion by means of a 
crank. A current of air thus obtained produces effects altogether 
superior to anything which can be accomplished by means of a 
fan-blast. The "middlings" grade themselves accurately ac- 
cording to their specific gravity, and fall purified into the com- 
partments destined for their reception ; while the light stuflfs, 
bran and germ, are held suspended and driven over the tail. 
The machine works without fan or stive-room, which latter is 
necessary whenever a fan is used, thereby reducing the risk 
of explosion and fire to a minimum, and avoiding all waste. 
VOL. XXV, — S. S. H 
