Page:Popular Science Monthly Volume 88.djvu/894

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��Popular Science Monthly

��''turbine discharge accelerator," because it can accelerate the flow of water through a turbine water-wheel. It is adjustable, and it can readily be regu- lated to the river conditions.

The illustrations will give a general

���This household size apparatus will sterilize one thousand gallons of water for five cents

idea of the new device. The results were so marked as to appear incredible. Some of them are as follows:

1. The turbine w'heel can be made to develop its normal rated power at half head.

2. The turbine wheel can be caused to develop nearly double its rated l)ower at its normal head. ( It will, of course, use more water in both cases).

3. The turbine can be made to develop a fair amount of power at proper speeds, when the head seems to be almost totally destroyed by high water. The latter conditions are extreme and are not often met in practice.

��Sterilizing Water by Ultra Violet Light

ULTRA violet light is not visible to the eye, yet it affects a photograph- ic plate, decomposes many chemicals, causes sunburn and sunstroke, and kills bacteria. Nature's purification of rivers owes something to the ultra \iolet portion of the sun's rays. A\ hy not use it to purify drinking water? That idea has actually been carried out at Saint Malo, at Rouen and at Lune- ville, all in France.

The best commercial source is the mercury arc in which mercury vapor in a high vacuum becomes luminous as it conducts the electric current. The ultra violet cannot pass through the glass. Hence, the lamp tube must be made of clear quartz, one of the few solids transparent to these rays.

The light tube is a "pistol lamp," as it is called, because it is bent into a U- shape and enclosed in a quartz jacket as a protection against the cooling eft'ect of the water. The pistol tube is im- mersed in the flowing water while the connections are outside the tank.

The capacity of apparatus now in the market varies from twenty gallons an It our to ten thousand gallons an hour or, hv increasing the number of units, to any figure for large city water plants. An experimental plant in one American city forces the water through concrete channels two feet wide, three feet deep and twenty-six feet long, affording a contact period of thirtv seconds with the ultra violet rays. The pistol lamps are spaced thirty inches apart, and in front of each is a baffle of wnred glass in which a rectangular opening is cut to divert the water against the quartz tube.

The smaller types are used in steril- ization of drinking water for homes, clubs, hospitals, factories, etc., purify- ing swimming pools, sterilizing water for ice plants and can even be found with armies in the field. The Austrian army carries a portal)le type on a motor car. In five minutes after starting the generator the soldiers fill their canteen with sterile and palatable drinking water. Tlie household size is efficient and ec- onomical.

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