Rawhide Boxes For Machinery

A practical machinist says:

"I have run a piece of machinery in rawhide boxes for fourteen years without oil; it is good yet, and runs at 4500 per minute. I put it in while soft, and let it, remain until dry."

Sprung Shafts

If a shaft springs in running, the trouble lies probably in either a too small diameter of the shaft for its weight and velocity, a set of unbalanced pulleys, or an unequal strain on either side by the belts.

Lubricant For Wood

A mixture of black-lead and soap.

How To Prepare Plaster Of Paris For Casts

Immerse the unburnt gypsum for 15 minutes in water containing 8 or 10 per cent of sulphuric acid, and then calcine it. Prepared in this way it sets slowly, but makes excellent casts, which are perfectly white instead of the usual grayish tint.

Transparent Casts

Beautiful semi-transparent casts of fancy articles may be taken in a compound of 2 parts unbaked gypsum, 1 part bleached beeswax, and 1 part paraffine. This becomes plastic at 120°, and is quite tough.

How To Bleach Glue

Soak in moderately strong acetic acid for two days, drain, place on a sieve, and wash well with cold water. Dry on a warm plate.

Moulding Architectural Ornaments

A good composition for this purpose is made of chalk, glue, and paper-paste.

Moulding Composition

Five parts of sifted whiting mixed with a solution of 1 part glue, together with a little Venice turpentine to obviate the brittleness, makes a good plastic material, which may be kneaded into figures or any desired shape. It should be kept warm while being worked. It becomes as hard as stone when dry.

How To Mould Figures In Paste

Take the crumb of a new-drawn white loaf, mould in a mass until the whole becomes as close as wax and very pliable. Then heat and roll with a rolling-pin. Mould it to the required shape, and dry in a stove.

How To Varnish Photographic Prints

Heat a piece of glass, and rub a little wax over it with a bit of cotton-wool. Pour water over the plate, and press the picture down upon it with a piece of filtering-paper. When dry, the picture is removed, and will be found to possess a brilliant surface.

How To Toughen Plaster Casts

Immerse in a hot solution of glue long enough for the mass to be well saturated. They will bear a nail driven in without cracking.

Plaster Models Mending

Sandarac varnish is the best material. Saturate the broken surfaces thoroughly, press them well together, and allow them to dry.

Plaster Moulds

Glycerine is said to be a good coating for the interior, but practical plaster moulders still use. as of old, a mixture of lard and oil.

Alloy For Filling Defects In Small Castings

Lead 9 parts, antimony 2, bismuth 1. This expands on cooling.

How To Extract Silver From Old Alloys

Dissolve in nitric acid and precipitate the chloride of silver with a solution of common salt. The silver is reduced to a pure state by mixing the chloride with an equal weight of bicarbonate of soda and smelting in a common sand crucible.