Boiler Incrustation

The following remedies have been used, with varying success, to prevent the incrustation of boilers.

1. Potatoes, in weight one fiftieth part that of the water, prevents the adherence of scale.

2. 12 parts of salt, 2½ parts of caustic soda, ⅛ part of extract of bark, ½ part of potash.

3. Pieces of oak-wood, suspended in the boiler and renewed monthly.

4. 2 ounces of muriate of ammonia in the boiler twice a week.

5. A coating, consisting ot 3 parts of black-lead and 18 parts of tallow, applied hot to the inside of the boiler every few weeks.

6. 12½ lbs. of molasses, fed into an 8 horse-boiler at intervals, prevented incrustation for six months.

7. Mahogany or oak saw dust in small quantities. Use this with caution, as the tannic acid attracts iron.

8. Carbonate of soda.

Non-Conducting Covering For Steam Pipes

Sawdust mixed with flour and water into a thick paste is a non-conducting covering for steam pipes, cylinders, etc. The flour should be made into a very thin paste, and then the sawdust is stirred in. The adhesion of this composition is very great when applied on clean surfaces of wrought or cast iron; but on copper pipes it is necessary to wash them first with a clay-wash, made with potter's clay, until it forms a thin coating, after which the sawdust and paste will adhere firmly. It is very simple to apply; a small trowel is all that is necessary. Lay on five successive coats one-fifth of an inch thick. Let the pipes or other objects to be covered be kept warm by the aid of a little steam, and let one coat be perfectly dry before applying a second. Should the pipes be outside, exposed to the open air, give them three or four coats of coal tar to make them waterproof, but if inside a building, it is not necessary. It is well to pass the sawdust through a riddle to cleanse it from the coarse fragments of wood which are always to be found amongst sawdust. Steam pipes so covered lose less heat than when covered by any other known or patented process sold tor that purpose. It is much less expensive and much more efficient.

How To Harden Wood Pulleys

Soft maple is often used in the construction of friction pulleys. If it is boiled in olive oil it will prove beneficial in a number of ways. It will harden the timber and render it less liable to split, but at the same time the gear will slip more after such treatment.

How To Prevent Belts Slipping

A piece of rubber belting fastened around the belt pulley of an engine will keep the belt from slipping.

Rasps

A farrier's rasp is an excellent tool for preparing a rough piece of wood or ivory for the lathe. Where only a small quantity of the material is required to be removed it will be found to be more convenient than the axe or paring-knife. There is also a somewhat similar tool used by shoemakers which, for smaller jobs, will be found equally efficient.

Soft Files

Small single-cut files or "floats" of various shapes not hardened, may be met with at some of the dealers in watchmaker's tools, which are useful in finishing small articles in hard wood, ivory, and also gold and silver; they are used sometimes by jewellers for finishing, on account of their leaving a smooth surface behind them instead of a rough one, as a cross-cut file does.

Amalgam Varnish

Melt together equal parts of bismuth, tin and quicksilver; when melted and cooled make it into a varnish with white of egg. It is used for the varnishing of plaster of Paris figures and others of the like kind. Some people recommended lead, but lead soon becomes tarnished, but tin and bismuth will keep bright.

Painting And Preserving Ironwork

A good black paint for coarse ironwork may be made by mixing plumbago with hot coal-tar. Equal parts of asphaltum and resin dissolved in common turpentine make also a good, cheap covering for heavy ironwork. For machinery, dissolve 2 lbs. india-rubber, 4 lbs. resin, and 2 lbs. shell-lac, in 5 galls, of benzine. This may be used with any other paint as a vehicle. Wrought-iron bridges are painted with white-lead as follows: The ironwork is first made clean by scrubbing and brushing it with wire brushes; this done, all the cavities and fissures are filled up with a putty of litharge, linseed oil, varnish, and white-lead; this filling being dry, brushing is repeated. Afterwards a paint is applied, consisting of 800 lbs. of white-lead, 10 galls, of crude linseed oil, 1 or 2 galls, of boileil linseed oil, and 1¼ gal. turpentine. This paint is repeated when sufficiently dry, and finally evenly overspread with white sand. Galvanizing is employed also to prevent rusting. A galvanizing paint consists chiefly of zinc powder and oil varnish. Rusting is further prevented by rubbing the red-hot iron with wax, tallow, pitch, or coal-tar. Rubbing with heavy petroleum is also well adapted for keeping ironwork clean.

Preparing Soft Solder

The following directions for soldering without fire or lamp may suit the querist: Bismuth, ¼ oz., quicksilver, ¼ oz., block tin filing, 1 oz., spirits of salts, 1 oz. Mix the whole together. Another soft solder for tin, etc. Take lead 1 part, tin 1 part, bismuth 2 parts; this melts in boiling water.

How To Clean Silver Filigree

Make a thin paste with cold water and cream of tartar, spread over ornaments thickly, fold in flannel, leave a week, then wash off with water, and they will be as good as new.

Bronzing On Metal

The article must be chemically cleaned up brushing with a mixture of fine pumice in dilute sulphuric acid, rinsed in pure water and dried. The bronze liquor must be applied quickly and evenly with a camel's hair brush, having first heated the article, just so as it can be held without burning the fingers.

Polishing Metals

A useful compound for polishing and cleaning metals is composed of 1 oz. carbonate of ammonia dissolved in 4 oz. water; with this is mixed 1G oz. Paris white. A moistened sponge is dipped in the powder, and rubbed lightly over the surface of the metal, after which the powder is dusted off, leaving a fine brilliant luster.

Imitation Marble

Mix 1 lb. finely powdered lime into a thick paste with water, and add ½ lb. of colophony or, what is better, Venice turpentine. Allow the mixture to stand for some time, and then work up with it suitable quantities of fine white chalk and various colored earths, adding a few drops of olive oil it necessary. A soft mass is thus obtained, which can be moulded, like plaster of Paris, to any desired form, or it can be rolled out on a warm metal plate, or passed under wooden rollers, into thin sheets, which can be glued to the surface to be decorated, like ordinary veneers, and left to harden. It hardens and takes a good surface. Any cavities that appear must be filled up with some of the composition mixed with oil of turpentine. The composition