Treatise on Mills and Millwork: On machinery of transmission and the construction and arrangement of mills

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Longmans, Green and Company, 1871 - Machinery
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Page 243 - ... action in a thoroughly practical way will effect an important desideratum. I. Chemical Processes : Watt and Burgess's Process. — This process, which, with some modifications, is extensively worked in America, consists in boiling wood shavings, or other similar vegetable matter, in caustic soda ley, and then washing to remove the alkali ; the wood is next treated with chlorine gas, or an oxygeneous compound of chlorine, in a suitable vessel, and it is afterwards washed to free it from the hydrochloric...
Page 74 - When no unguent is interposed, the friction of any two surfaces (whether of quiescence or of motion) is directly proportional to the force with which they are pressed perpendicularly together ; so that for any two given surfaces of contact there is a constant ratio of the friction to the perpendicular pressure of the one surface upon the other. Whilst this ratio is thus the same for the same surfaces of contact, it is different for different surfaces of contact. The particular value of it in respect...
Page 75 - When no unguent is interposed, the amount of the friction is, in every case, wholly independent of the extent of the surfaces of contact...
Page 249 - On some occasion, a visitor, to whom this was shown, observed, with affected solemnity, that the letter involved also a miracle ; for the paper on which it was written was not in existence till several hundred years after the mother of our Lord had ascended into heaven.— English Connoisseur.
Page 232 - ... the press ; the door L is then opened and the whole of the seed is discharged from the chamber B by the action of the revolving stirrers H. The seed falls through a funnel M, under which is placed a bag of suitable dimensions to contain a sufficient quantity of seed to make a cake weighing 8 Ibs. after the oil is expressed from it. Each of the chambers in the heating kettle will contain sufficient seed for charging one single press; the heating of the seed is therefore a continuous operation...
Page 230 - ... considered. These are three in number : — the Dutch or Stamper Press, which was invented in Holland : the Screw Press ; and the Hydraulic Press ; both of which were invented in this country. Before considering the comparative merits of these three presses, it will be advantageous to refer generally to the course of operations to be performed previous to the compression of the seed, which is the last of five operations that it has to undergo. The first operation consists in passing the seed...
Page 76 - From a paper lately read at the Institution of Civil Engineers in London, on the comparative friction of steam engines of different modifications, it appears that, as respects the friction caused by the strain, if the beam engine be taken as the standard of comparison — The vibrating engine . . . .has a gain of 1-1 per cent, The direct...
Page 75 - VIII, leads to the following remarkable conclusion, easily fixing itself in the memory, that with the unguents, hogs* lard and olive oil interposed in a continuous stratum between them, surfaces of wood on metal, wood on wood, metal on wood, and metal on metal, when in motion, have all of them very nearly the same co-efficient of friction, the value of that co-efficient being in all cases included between 0,07 and 0,08, and the limiting angle of resistance therefore between 4 and 4 35'.
Page 75 - ... -10. Hence it is evident that where the extent of the surface sustaining a given pressure is so great as to make the pressure less than that which corresponds to a state of perfect separation, this greater extent of surface tends to increase the friction by reason of that adhesiveness of the unguent, dependent upon its greater or less viscosity, whose effect is proportional to the extent of the surfaces between which it is interposed.
Page 138 - Bruiser is similar to that ordinarily employed on shore in this country, with such modifications only as were necessary to adapt it to its novel position, and fit it to sustain the constant and varying motion of the vessel at sea. These difficulties were overcome, and the mill was found to answer admirably, grinding in almost all weathers at the rate of 20 bushels or 1120 Ibs.

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