Page:Popular Science Monthly Volume 91.djvu/306

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290

��Popular Science Monthly

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��An Open Shelter for the Yard or Flat Roof of a Building

THE flat roofs of tenement and apart- ment houses in large cities are often used as breathing places by the tenants. Shelters can be built upon them at small cost as protection from sun and rain. Our illustration shows one of these shacks, which is the result of the cam- paign for the preven- tion of tuberculosis by the New York State Department of Health.

In the construc- tion, 2 by 4-in. tim- bers are used for the frame, and sid- ing boards for the back and sides. The front of the shack should face slightly to the east of south and be left open, but it should be pro- vided with a canvas curtain, tacked on a roller so that it may be closed in stormy weather. The most economi- cal materials are rough boards for the frame and tar paper or something similar for roof- ing. The material list

4 sills, 12 ft. long by 2 by 4 in.

5 floor joists, 12 ft. long by 2 by 4 in. 14 studs, 14 ft. long by 2 by 3 in.

5 plates, 12 ft. long by 2 by 3 in. I front plate, 12 ft. by 2 by 6 in. 1 rail for sliding sash, 12 ft. long by 2 by 8 in. 9 rafters, 14 ft. long by 2 by 4 in. 300 ft. of novelty siding. 250 ft. of shiplap roof boards. 3^ roll of roofing material. 10 pieces of i-in. round for roofing. 1 canvas curtain on roll. 4 sliding sash; I casement sash and frame. Strips of sliding sash, hardware and paint.

��Sterilization Is the Essential Factor in Canning Vegetables

THE great secret of canning or preserv- ing lies in complete sterilization. The

��air we breathe, the

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��Plans for the construction of an open air shelter shack for a yard or open air sleeping quarters on a flat roof

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��water we drink, all fruits and vegetables, are teeming with mi- nute forms of life which we call bac- teria, or molds, or germs. These germs are practically the sole cause of decom- position or rotting. The exclusion of air from canned articles, which was formerly supposed to be so important, is unnec- essary provided the air is sterile or free from germs. The exclusion of air is neces- sary only be- cause in exclud- ing it we ex- clude the germ. In other words, air which has been sterilized or freed from germs by heat or mechanical means can be passed continu- ously over canned articles without affect- ing them.

Germs which cause decay may be divided into three classes — yeasts, molds, and bacteria.

��Yeasts are easily killed, so they can be left out of consideration in canning vegetables. As a general rule, molds are likely to attack jellies and preserves. The spoiling of vege- tables is due primarily to bacteria. Bacteria are also much more resistant to heat than yeasts. They thrive in products like milk and in meats and vegetables rich in protein, such as peas, beans, etc. Keeping these products at boiling temperature for about 1 hour, upon two or three successive days will kill all bacteria, even the seed forms, which are difficult to destroy.

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