This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Another home-made filter, continuously acting, for filtering and aerating water on a small scale, and without going into the expense of applying machinery for aerating, is recommended by a correspondent in the National Bottlers' Gazette, and will be described here. It is claimed that it never becomes foul owing to the complete aeration of water, and that this filter will serve for years; but we urgently suggest the frequent cleansing of this filter also to prevent, clogging up of its pores with the retained impurities, which would decrease its purifying capacity gradually and make it worse, as the large amount of impurities which accumulate could at last not all be "consumed by oxygen". By frequent cleansing or renewing of the filter medium it will certainly be a practical filter, and preserve its purifying power. The description of this filter runs as follows:
"The body of the filter may be made of wood, galvanized iron or earthenware, and of any appropriate size. A horizontal partition forms a receptacle at the top to receive water. The flow of water from this receptacle is regulated by a cock. Upon the perforated bottom of the next compartment is placed a body of gravel, above which is sharp, coarse sand. Under the cock is a distributing plate, upon which the stream of water strikes and is divided and distributed over the surface of the sand. Below the perforated bottom is the lower compartment, that receives the filtered water, which is drawn out through a cock or faucet. Formed in the body, just below the upper partition, is an opening, closed by a wire door, that permits free access of air to the compartment; through this opening the stem of the cock may be turned to regulate the flow of water. In the side of the lowest compartment is a similar opening for the passage of air to the filter below the filtering material, so that the water is plentifully aerated in the filter. The free access of air is of special importance in the centre compartment, as the water, being divided into spray by the plate, will be brought into intimate contact with the air. The air is said to mingle with the sand, causing the water to be minutely divided, and, by oxidizing the impurities, will have a constant 8 cleansing effect. The water is never permitted to enter in such quantity as to cover the sand".
The same kind of filter as described above may be filled with another filter-medium as follows: On the felt or flannel placed over the perforated false bottom, put an inch layer of short fibrous asbestos, squeezing it close together, then add a two or three-inch layer of carefully washed sand; on top of this a ten-inch layer of coarse wood, or, better, animal charcoal, previously sieved and freed from the pulverized parts. Then upon this add at least a layer of sand again. The layers of coal and sand may be increased to suit, but the two uppermost layers ought to be the largest. Both the upper layers renew every two or three weeks, the others every six to nine weeks. This makes an excellent filter if cleansed out regularly.
Another practical home-made filter is shown in the following illustration: - It consists of a clean wooden tank, if possible oak, with an open top, supported by iron hoops that are painted to protect them from rusting. In the midst of the bottom screw a hole about one inch and a half wide, and adjust by means of a perforated cork or a coupling a wooden or iron faucet h to draw off the filtered water. Over the hole lay a piece of felt f, through which bore a hole to correspond with the faucet. Upon this felt place an earthenware flowerpot c, with its open part downwards. It should be about an inch high and the felt large enough to cover or close its open part. Any similar earthenware cylinder will answer. If the flowerpot or other earthenware cylinder has any opening on its bottom, which is now turned upwards, close it with a cork. Put upon the earthenware vessel a clean brick st, to hold it down and give it a firm stand. Then cover the bottom of the filter around the earthenware pot with a layer of carefully washed sand, ss, then put on a layer of well-sieved coarse wooden or better, animal charcoal, kk, reaching above the inserted vessel. On top of the charcoal lay carefully a few sheets of white filtering paper, covering the whole surface thoroughly, and then add a layer of white, carefully sieved and washed sand s. The water, w, running into the filter, penetrates the sand and charcoal layers and filters into the earthenware vessel, from where it flows out through cock, h.
The sides of the earthenware vessel should not be much over a quarter of an inch thick, and the vessel in general not too much burned. The earthenware vessel must be porous, and should be first tested in this respect before using it.
To test it, put it in water, opening upwards, and put a stone or something else across to hold it m position. The water should flow around it, not over the top. Close the opening at the bottom tightly with a cork. In a short time the vessel ought to be filled with water; if not, reject it and try to get another one to suit the purpose. The filter should rest on a support.
Fig 40. - Home-Made Filter.
This arrangement is a very effective filter, cheap to put up and combines many advantages, making other filtering arrangements superfluous. Every six to twelve weeks, according to the quality of the water, a renewal of the sand and charcoal layers and of the earthenware vessel is necessary. Of the latter keep a stock on hand - they are cheap.
This filtering apparatus is plain, practical and effective; still we shall describe two more home-made filters, to give the reader and the enterprising manufacturer a chance to try for himself and find out what suits him best.