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ainst excessive cold. Great care should be taken that a thorough ventilation be given in the first mentioned type. In the other, more substantial silos, ventilation must be watched, and all communication with the exterior closed as soon as the temperature falls to or near freezing. During the last campaign many manufacturers experienced great difficulty in keeping the blades of slicers sufficiently sharp to work frozen beets. Sharpening of blades is an operation attended to by special hands at the factory; and under ordinary circumstances there need be no difficulty. However, it is now proposed to have central stations that will make a specialty of blade sharpening. Under these circumstances manufacturers located in certain districts need give the matter no further thought, let the coming winter be as severe as it may. Some success has been obtained by the use of sulphurous acid in vacuum pans. Great care is required; the operation cannot be done by an ordinary workman. It is claimed that graining thereby is more rapid and better than is now possible. Chemists agree that the operation is more effectual by bringing sulphurous acid in contact with sirups rather than juices; it is in the sirups that the coloring pigments are found. Sulphurous acid is run into the pan until the sirups cover the second coil. In all cases the work must be done at a low temperature. Height of juice in carbonatating tanks is only three feet in France, while in Austria it is frequently twelve feet. The question of a change in existing methods is being discussed; it necessitates an increase in the blowing capacity of machine; since carbonic acid gas has a greater resistance to overcome in Austrian than in French methods. Longer the period juices are in contact with carbonic acid, greater will be the effect produced. Ferric sulphate has been very little used for refuse water purification, owing to cost of its manufacture. If roasted pyrites, a waste product of certain chemical factories, are sprinkled with sulphuric acid of 66 deg. B., and thoroughly mixed for several hours, at a temperature of 100 deg. to 156 deg. F., the pyrites will soon be covered with a white substance which is ferric sulphate. Precipitates from ferric sulphate, unlike calcic compounds, do not subsequently enter into putrefaction. Efforts are being made to convince manufacturers of the mistake in using decanting vats, in connection with first and second carbonatat
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