Purification Spirits By Filtration
Instead of resorting to repeated distillations for effecting the purification of spirits, Schaeffer proposes the use of a filter.
In a suitable vessel, the form of which is not material, a filtering bed is constructed in the following manner:
On a false perforated bottom, covered with woollen or other fabric, a layer of about six inches of well-washed and very clean river sand is placed; next about twelve inches of granular charcoal, preferring that made from birch; on the charcoal is placed a layer of about one inch of wheat, boiled to such an extent as to cause it to swell as large as possible, and so that it will readily crush between the fingers.
Above this is laid about ten inches of charcoal, then about one inch of broken oyster shells, and then about two inches more of charcoal, over which is placed a layer of woollen or other fabric, and over it a perforated partition, on to which the spirit to be filtered is poured; the filter is kept covered, and in order that the spirit may flow freely into the compartment of the filter below the filtering materials, a tube connects such lower compartment with the upper compartment of the filter, so that the air may pass freely between the lower and upper compartments of the filter.
On each, of the several strata above described, it is desirable to place a layer of filtering paper.
The charcoal suitable for the above purpose is not such as is obtained in the ordinary mode of preparation. It is placed in a retort or oven, and heated to a red heat until the blue flame has passed off, and the flame become red.
The charcoal is then cooled in water, in which carbonate of potash has previously been dissolved, in the proportion of two ounces of carbonate to fifty gallons of water.
The charcoal being deprived of the water is then reduced to a granular state, in which condition it is ready for use.
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