should be provided by means of tile drains laid below the sewage tile as shown in Fig. 7. In some cases an impervious stratum underlying the filter earth is un- derlain by a stratum of sand. Cases have been noted in which this impervious stratum has been broken by dynamite at 15 to 20-ft. intervals along the tile line, to provide natural drainage.
If surface disposal is not feasible, as when the soil is compact and nearly im- pervious, or is swampy making underdrain- age hard to arrange, disposal by inter- mittent flow and filtration is necessary.
The sand filter usually is a bed of sand 3 to 4 ft. thick, which is fine on top and gradually increases in size to coarse gravel at the bottom. The sewage from the tank is distributed over the filter by means of tile laid loose-jointed over the surface in much the same manner as in
��Num- ber per- sons.
� � � �Siphon Chamber.
�Siphon diam- eter.
� �Sand filter or heavy loam distribution.
�Sandy or porous soil distribution.
�Width inside.
�Length inside.
�Depth.
�Width inside.
�Length inside.
�Mini- mum depth.
�Width inside.
�Length inside.
�Mini- mum depth.
�6
8 12 KS 25 35
�Feet. 4 4 4 4 4 4i
�Feet.
6
6\
7
8 10 12
�Feel.
4 5 5
5 5
�Feet. 4 4 4 4 4 4
�Feet. 3
4
5
6
6i
6J
�Ft. in.
2 4 2 4 2 S
2 5
3 2 3 2
�Feet. 3 3
3 3
3,1 31
�Feet 2
2i
4
4
4
4J
�Ft. in. 2 4 2 4 2 5
2 5
3 2 3 2
�Inches. 3 3 4 4 5 5
��The above table is computed on the basis that the inlet and outlet of the settling chamber are placed with inverts twelve inches below the roof, making the sewage depth twelve inches less than the inside depth
��the ground surface distribution system. The filter should be sufficiently porous and there should be sufficient natural or artificial underdrainage to allow every dose of sewage to sink away rapidly. Sewage should not stand on the surface of the filter for any length of time, as this soon destroys its purifying properties. About 45 sq. ft. of filter should be pro- vided for each person served by the sewer. The area should be divided into from three to five beds so that each bed may be al- lowed to rest occasionally. A plan and a partial section of a sand filter for a family of eight persons is shown in Fig. 8.
In constructing a filter, a sufficient area should be leveled off and small earth embankments be made 18 in. to 2 ft. high to inclose the beds. The depth of the
��filtering material will depend largely on the porosity of the subsurface and the means of underdrainage, but it is well to have it not less than 2 3/^ ft.; 3 to 5 ft. is better, but the depth should not ex- ceed 6 ft. A good plan is to allow a minimum of a cu. yd, of filtering material for every 50 gal. of sewage flow.
Lighting an Alcohol Lamp with a Glass Rod
PLACE a quarter of a teaspoonful of per- manganate of potash crystals in the bottom of a glass tumbler, moistening them with a few drops of water. Then, just barely cover the mixture with concentrated sulphuric acid — oil of vitriol. A very vigor- ous action will at once begin, and a glass rod dipped in the mixture, then touched to the wick of an alcohol lamp will immediately create a flame. The chemical action in the tumbler produces ozone, a concentrated form of oxygen, and the rapid oxidation of the alcohol in the wick brings it to its kindling temperature and lights the lamp. A little ether poured on a glass plate can can also be ignited by simply touching it u4th the glass rod after the rod has been dipped in the
��tumbler. This experiment may be used to advantage by the house magician to fill out the program of an evening's entertainment.
��To Prevent Mildew in a Damp Clothes Closet
THE careful housekeeper is often greatly troubled and perplexed by rust and mildew formations caused by damp closets. This state of affairs can be easily remedied if an earthenware bowl or a deep plate full of quicklime be placed in the closet. The lime absorbs the moisture, sweetening and disinfecting the damp corners. Rodents and insects that are likely to congregate in such places greatly dislike the odor of the lime. When the lime becomes slaked it should be thrown away and a fresh supply substituted.
�� �
