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Cleaning Sooty Bricks Soft coal smoke has spoiled the appearance of my pressed-brick house. How can I remove the sooty deposit ?--G. T. S.

Make a mixture as follows: One pint of liquid ammonia ; 1 gallon soft soap; 2 pounds powdered pumice. A soft, pasty sub';tance should be the result. Brush the dust off the brickwork. Then apply the mixture with an ordinary new whitewash brush. At the end of some 20 minutes, take a scrubbing brush and use it vigorously. Rinse down with a hose, or clean with a large sponge and lukewarm water. The bricks will come out as if new.

Testing Incandescent Lamps Can you suggest a method of testing incandescent lamps, to find out whether or not they will burn?-H. O. J.

coal, puddled bar, or blister steel, and charcoal. The crucibles are made of clay or graphite, with a capacity of 50 to 85 pounds. The charge is put into the crucible, and after melting is allowed to stand for a time, called the “killing period,” and then poured into moulds.

In American practice, graphite crucibles are used, which are made from a mixture of fire-clay and sand, and about 50 per cent graphite. This mixture is ground, allowed to stand for a few days, and is then moulded by being pressed into a wooden mould. When dry, it is baked in a kiln. These crucibles can be used about five times, if the successive charges are gradually diminished in amount.

The crucible is charged cold. The pieces of iron are surrounded with charcoal, with a little manganese, and sometimes a little salt or ferrocyanide of potassium mixed with it. The crucible, after being covered, is placed standing on the coal in a hot furnace. After three hours, during which the contents are melted, the cover is lifted, and the melter examines the charge to determine the length of the “killing” period. During this period, which is about 45 minutes, the metal is becoming tranquil and is taking silicon from the sand in the walls of the crucible. This silicon prevents blow-holes. At the right time and temperature, the crucible is lifted out and the slag skimmed off. The metal is now ready for casting or “teeming.”

The ingots are graded and hammered into bars for different uses. Crucible steel furnishes the finest grades for cutlery and machine tools; it is superior to Bessemer and open-hearth steel, because pure materials are used and the process is carried on in a closed vessel, thus protecting the metal from sulphur gases from the fuel.

LAMP TESTER,

A contrivance of the sort here illustrated will probably meet with your requirements. It is made by taking a piece of board of such length as may be desired, and fitting it with a number of lamp receptacles (Y). These are screwed to the board, and wired. Such connections as convenience dictates are made. The bulb to be tested is inserted in the receptacle. A plan view of the device is shown at 2.

Pictures by Flash-Light Would you please explain how to take a picture by flash-light?-O. S.

Place a card for a reflector behind the flashlight, the latter being about 25 inches from the camera and level with it.

When ready, open the camera shutter, as in a time exposure, light the flash, and close the shutter at once.

Making Crucible Steel Describe the crucible process of making steel?-E. W. R.

The materials are bar iron, with char

Concrete Foundations 1. Can you give me some practical points on using concrete for foundations ? 2. What is cinder concrete?J. M. M.

1. The first thing in the use of concrete to be considered is, of course, the mixing of the materials. One part cement, three parts sand, and four parts

reinforcing is advisable, and especially upon soil liable to settle or crack. Old steel rails may be used, where reinforcing is necessary. There is a tendency to use more metal for this purpose than is really needed, however.

Concrete should not be allowed to freeze during setting. Freezing after setting, however, seems to do it no special injury. In foundations, retaining walls, etc., a saturated salt solution is sometimes mixed with the concrete. This prevents freezing, and the material seems to suffer no injury from its presence.

2. Cinder concrete is made by taking boiler cinders and mixing them with cement. The concrete so made weighs far less than stone or gravel concrete. The material loses considerably in strength, however. It does well enough for floors, but should never be used in damp places, as the porous cinders readily absorb moisture. It is equally faulty in the construction of beams and pillars.

AIR-CHAMBER FOR PUMP.

broken stone make generally the best proportions. In cases where gravel is easy to procure, this may be substituted for stone. In the center of a large block the proportion of stone and sand may be increased with very satisfactory results.

Mixed concrete should never be shoveled into a hole full of water, as the stone or gravel will sink first and the other material follow according to its specific gravity. Where it is necessary to lay the foundations under water, the dry mixture must be placed in bags and so deposited. While the concrete thus assumes an irregular form, this method has proved highly successful in building footings. The following method is employed where the forms extend clear to the bottom under water. A special shovel or bucket is filled with the concrete and lowered to the bottom, where it is emptied.

Concrete in foundations, even in large buildings, is rarely reinforced. Where the foundation is upon uneven ground,

Place of Air-Chamber on Steam Pumps

Where should the air-chamber on a steam pump be placed?-E. B. M.

The air-chamber on the discharge should be placed at the highest point of the valve-chest and above the delivery opening so that the air will not tend to slip out with the water. Even then the air will be gradually absorbed by the water; and provision must be made for renewing the air-cushion — either when the pump is not in use, by admitting air through a cock and allowing some water to escape from the valve-chest; or continuously, by an automatic pump.

The suction air-chamber should be so placed that the stream of water flowing to the pump will cushion against the air in it without changing its direction abruptly. Two positions which fulfil this condition are shown in the accompanying figure. If it is impossible to place the suction chamber in such a position, the capacity should be increased considerably, the amount depending on the speed at which the pump is to be run.

New Cure for Appendicitis In Germany collangol, a silver solution, is curing appendicitis without the necessity of an operation.

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THE Sierra Nevada Mountains climb up the mountain side has cut the

must go to work. Mr. E. H. heart out of profits and diverted con1 Harriman, the “little wizard" of siderable freight to other lines.

the railroad world, has decided But—as is often the case when great that they have been idle long enough. financial genius and splendid engineering Worse than that, they have been ability take hold of a case together—what an absolute obstruction to transportation. seems almost a miracle has now been acIt has taken three or four panting loco- complished. The mountains themselves motives to painfully pull a short train of are to haul the freight trains to their own loaded freight-cars up the steep grade summits. Harriman has found out how from Truckee, Cal., on the Southern Pa- to lift himself by his boot-straps. cific, to the summit of Emigrant Pass, The little mountain streams, starting about 5,000 feet above sea-level. That from the melting glaciers which cap the Copyright, 1907, by The Technical World Company

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