The presence of iron in water for carbonating is, as a rule, very troublesome. The removal of iron from water is sought by various methods. If it is present in soluble form, it can only occur as protoxide, in combination with a soluble acid. As soon as an opportunity offers to transform the protoxide, by encouraging the absorption of oxygen into an insoluble oxide, it becomes possible, by effecting the removal of the latter, to accomplish the purpose. In the purification of water containing iron, some chemical process is necessary, and with the aid of which the desired result can be accomplished more rapidly and with greater certainty. Peroxide of hydrogen and 'permanganate of potash are of the greatest practical value in this connection. A small quantity of both, well mixed with the water, will suffice in a short time to effect the oxidization of the iron, and thereby to cause its precipitation. In many instances, however, it is so finely divided that it only settles with difficulty; and in the infinitely small quantity in which it is commonly present in water, it is scarcely noticeable. To assist precipitation of the oxidized iron, pass the water, previously mixed with the chemicals and allowed to stand, through several thicknesses of filter paper. On this the iron particles will be completely precipitated, and, owing to their fine division that will occur in the pores of the paper, the oxidization of the iron, which may not previously have been effected, will be secured. Ammonia water {aqua ammonia) is said to precipitate all iron in solution, but will not clarify it. For the latter purpose, alum gives excellent results. Perchloride of iron, will also throw down the iron. To each gallon of the water the addition of about three drachms of a five per cent, solution of perchloride of iron precipitates the iron in the form of a brown sediment. Then siphon off or filter. When boiling the water oxides of iron are removed by subsidence. Then filter carefully. Caustic soda or potash, on being added to water in small quantities, will also precipitate oxide of iron.

Removal Of Manganese And Silica From Water

Manganese and silica are removed by subsidence when boiling the water. It is necessary, however, to filter afterward, in order to be sure that all the undesirable particles after precipitation are removed.