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.
The purification of water for the pur. pose of manufacturing beverages, whether carbonated or otherwise, is a fruitful subject of discussion, and one which should always engage the attention of the trades interested. The modes of purifying water are either mechanical or chemical, according as the impurities are in suspension or in solution. From suspended impurities, causing more or less turbidity, water is purified by subsidence and by filtration. On the largo scale subsidence is carried on in reservoirs, on the small scale in water-butts, tanks, and cisterns. The process is necessarily slow. The deposited matter should periodically be removed. In semi-barbarous countries muddy water is sometimes fined or cleared by the addition of the mucilaginous pulp of certain fruits, after the manner in which wine, cider and beer are clarified, by the addition of white of egg or of isinglass. The glairy matter slowly coagulates, inclosing the suspended matters as in a net, leaving the fluid clear. Filtration is conducted on the largest scale through gravel and sand, through spongy iron also; on the small scale through spongy iron, carbide of iron, charcoal, sponge, cloth, paper, stone and some other materials being occasionally employed. The chief objection to filtration is the liability of a portion of the impurities to decompose, and to increase instead of decrease the impurity of water subsequently passed through the filters. To prevent such an unfortunate result the filters must be duly cleansed.
Impurities in solution are of a mineral nature or they are organic; that is, of an animal or vegetable character. From the point of view of bottlers, dissolved carbonate of calcium in undue quantities (chalk, or less correctly "the lime") in water is an impurity. They are removed by chemicals, or by distillation and boiling.
To remove organic matter from solution in water oxidation by the oxy-gen of the air is the only practicable process. This action goes on directly but slowly in lakes or other sheets of water exposed to air. It goes on more rapidly when air and water are well mixed, as in the tumbling of water down weirs, cataracts and waterfalls, and in the rushing of rivers along rocky beds. It goes on most satisfactorily when water percolates through porous and therefore air-laden soil on its way to springs, wells, etc.; hence, by the way, the value of deep wells, the water of which is fifty to a hundred feet below the surface of the ground, for the rain-water supplying such wells, even if fouled at the surface, usually becomes converted into pure water before it reaches or becomes part of the water in the well. Filters, fortunately, act chemically as well as mechanically, in so far as they bring the organic impurities in the water and the oxygen of the air into closer contact, and, therefore, under good conditions for that chemical attack on each other which results in the entire alteration of both into a minute quantity of harmless nitre added to the water and a small quantity of carbonic acid, which gives desired aeration to the water.
To make this chemical action of the filter continuous it is necessary to constantly supply the requisite oxygen. For it must be distinctly understood, that the chemical action of the filter lasts only as long as its store of oxygen lasts. A constant supply of oxygen is kept up by the free access or the continuous circulation of air, and every filter should be so constructed as to allow such a free circulation - the aeration of the water. If this aeration is carried on by mechanical appliances and under pressure it is the more effective.
On this subject the National Bottlers' Gazette published a series of valuable and instructive articles which are very beneficial to the trade, and are in the main part reproduced here.
To Mr. R. d'Heureuse, New York, an expert in the matter, we are indebted for practical information. He is the patentee of several practical inventions on "Air-Treatment," and so also is Prof. Albert R. Leeds, of Hoboken. The latter's system of aeration and filtration is very much similar to that of the former. "We understand also that both systems are now under the operation of a Company.