PURIFYING APPARATUS, is of use in many industries and economic processes, partic ularly in the water supply of communities where the available source does not yield a pure product. Aside from the various chemical treatments of such waters the electrolytic sys tem has found favor in that it purifies without adding some other ingredient. It has been found that certain metals are capable of produc ing, while under the action of an electric cur rent immersed in the liquid to be purified, an insoluble hydroxide of the chlorides and sul phates held in solution, these being set free by the action of current passing through the liquid (see ELECTROLYSIS) ; the oxygen evolved at the anode decomposing and oxidizing impurities of animal and vegetable origin, leaving the water clear, free from odor and disease-breeding germs, sparkling, with a pure water taste (see DISTILLATION). For municipal supply, means are provided for the generation of electricity by either hydraulic or artificial power, using large basins containing the electrodes in which the oxidation takes place; the water passing thence into a coagulating section provided with means to retard the suspended matters; the water flowing thence down an inclined weir for the purpose of aeration, into another compartment of the basin containing screens, which clarifies it from all sediment, thence to storage reser voirs, occupying small space as compared to sand bed filters and automatic in operation. The apparatus for potable and industrial use consists of vessels capable of working under high pressure as for boiler feed purposes, one of which contains the electrodes or a series of them for very large supply; the electrodes being connected to a suitable source of electric supply, the vessels being provided with air-valves and insulators to prevent the grounding of the cur rent, and connected to other vessels by suitable conduits to remove the suspended matters, thus permitting a constant flow of the water through the apparatus, requiring small space and in stalled at any convenient point. For apartment houses and hotels, and establishments for bot tling carbonated waters small installations are quite efficient. They are arranged so that the motor may be run by the hydraulic pressure in the water main if desired. The current con
sumption is very as the resistance of the water is utilized in the treatment.
In the gas industry the Ipurifier° consists of a number of sieve-like trays placed in tiers. These are filled with the purifying material and the gas is compelled to pass through them con secutively. In the first purifier the trays are filled with lime thiocarbonate and some sul phurets which remove the poisonous carbon dioxide, although increasing the content of sulphureted hydrogen. The second purifier contain slaked lime, and removes nearly 211 the carbon disulphide and part of the sul phureted hydrogen. The third purifier may be a duplication of the second, or, if the gas is not too foul, it may go at once to the last purifier, filled with iron oxide, which removes the last traces of the sulphides and sulphurets.
In the flour-milling industry the purifying apparatus is pneumatic. After the grain has been through the fourth pair of breaking rolls and is in the form known as semolina, ready to be ground into flour, it is passed through the purifier, a long silk-covered sieve of varying meshes, enclosed in an air-tight compartment, The sieve dips downward on a slight grade and is shaken by appropriate machinery. At the top of the purifier is an exhausting fan which sucks a draught of air up through the sieve and the °semolina° which is traveling down the grade upon the silk. The chaff and light fibrous mate rial which has no food value is carried off into side channels by the draught, while the heavier food parts of the grain continue down the sieve until they come to a mesh which they can pass through, being thus sorted as to size for further treatment. The material removed by the draught amounts to from 10 to 15 per cent of the grain. This is again passed through a purifier of somewhat different weave, and a part of it is recovered and added to the olina to he ground. The purifying chamber is provided with glass windows through which the process may be watched, and the arrangement of fan and air valves is such that the force of the draught may be adjusted with the greatest delicacy.