Parifiers.—The George T. Smith purifier, so well and fa vorably known, is regarded as the standard machine of it-s class. The main features of this machine have never been departed from, and are: An upward current of air through the covering of a reciprocating sieve, clothed with silk of increasingly coarser mesh from head to tail ; an inclosed air space above the sieve, divided by transverse partitions into separate compartments having practieally no communication with each other, and each opening into the chamber of nil ex haust-fan through an adjustable valve, arranged to regulate the strength of the air-current through each compartment separately ; a series of dust-settling chambers or testing pockets, corresponding in number to the compartments above mentioned, and it brushing device oper ated automatically and working against the under side of the since clothing. This com bination has proved a very efficient one. There are numerous other makes of purifiers. but the Smith purifier may be regarded as a standard machine. The use of lust-collectors in eonnection with these machines has led to economy of space and increase in convenience in providing for the Ilti,4-la11en air coming from the purifier-sieve.
The Prinz dust-collector is favorably known, and has long since settled the knotty dust room quest ion.
A new principle. that of the "cyclone" dust-eoll rotor, has recently been put into practical operation, the essential features of which are embodied in the machine noted below.
This machine, which bids fair to be a formidable rival to the sieve purifier and attached dust-collector, was lately devised by Mr. N. W. Holt, of Manchester, Mich., and made by the Knickerbocker Co., of Jackson, Mich. Fig. 13 shows the exterior, and Figs. 14 and 15 the in terior. The stock is fed into the feed-spout it upon each side of the machine. Two grades of stock may he handled at the same time. From the feed-spout it passes to the feed-box B. which vibrates with the sieve or shaker, causing the stock to flow over the lower overlapping shelves in a thin, even sheet, where it is acted upon by the air-current, as shown. The purified middlings then pass out at spouts C C, the cut-off at 11, and the dust at spout E. The fan placed at the top provides the air-circulation. The upper series of shelves shown are air-gates adjustable to suit the intensity of the air-current required at the several points of the sieve, while gates at the eye of the fan control the air-circulation as a whole. The dust-laden air is
discharged from the fan through the pipe leading downward from the top part of the purifier into what is called the cyclone part of the machine, where the dust and air separate, the dust eventually settling at the bottom of the cone-shaped part and passing away from the machine, the air returning through the sieve, to be again used. The same air is used over and over, and, not being renewed from without the machine, excludes the possibility of smoke or dust from the external atmosphere affecting the products. No cloth is used, and the air being confined inside the machine renders it dustless. The power required is very small, a driving pulley 7 in. diameter and 31 in. face, running COO revolutions per min., being a11 that is re quired to drive it. The capacity of the machine as now made is equivalent to one medium sieve purifier.
Bran-Dusters.—Economy in the production of high-grade flours calls for proper cleaning of the bran. The effect of the bran rolls is to flatten the bran, leaving it broad and flaky and loosening the adhering particles, so that by subsequent treatment by the bran-duster these particles are regained and further treated. The latter operation is performed in the machine shown in Fig. 16, which consists of a rapidly revolving shaft on which are mounted brushes running lengthwise of the shaft and made adjustable toward or from the slowly revolving dusting-ease which surrounds them. This dusting-case, clothed with fine wire-cloth, is, in this machine, cone-shaped, the material tieing fed and discharged as indicated in the engrav ing. A brush outside the wire-cloth keeps it clear, and the conveyer beneath serves to handle the products coming through the cloth. The shaft makes from 400 to 450 revolutions per min., according to size of machine, the pulleys 14 X 7 in. and 8 X 5 in. respectively. The sizes of machines given handle the offal from mills of 600 to 60 bbls. capacity in 24 hours.
Books for reference: Gradual Reduction Milling, by L. U. Gibson ; Flour Manufacture, by F. Kick, Fowles' translation, 1888; Die asterreichische lloclnallerei, by Franz Kreuter, 1884.
ne : see Key-Seat Cutters and Nut-Facing Machine.