Chapter II

Gum-ammoniac 6
Mastic 60

The sturgeon’s bladder is dissolved in spirits of wine separately, the gum-ammoniac and mastic also, but with a minimum of spirit; the two are then combined.

A cement which will resist the action of spirits of wine will often be very valuable, as when large lids are to be fastened to jars containing anatomical preparations. One is made as follows:--

Cleaned manganese powder 20
Soluble silicate of soda 10

This must be freely used to make the cover adhere. When in time it shall become brittle, coat it over with a thick solution of asphaltum in turpentine or petroleum.

TO SEAL BOTTLES very securely, roughen the opening or mouth with a file or glass-paper, drive in a hard cork till half-an-inch below the top, and then seal it with silicate of soda mixed with marble-dust.

CHLORIDE OF ZINC added to silicate of soda and oxide of zinc forms a very good cement, which will resist most influences.

BREAD macerated with glue or gelatine, with a little glycerine, makes an admirable substance for artificial flowers, casts, medallions, &c. If worked with gum-arabic and a little alum, or dextrine, or common mucilage, we shall have the same result. It can also be worked with thin varnish or gutta-percha cement; also with diluted sulphuric or nitric acids to produce a hard substance. It may here be observed that _bread_ is for certain work far superior to flour or starch paste, since the combination with _yeast_ causes a development of cellular tissue, the result of which is a firmer and more wax-like substance. I was led to observe this at first, not from what I read of the action of acids on bread, but from observing the bread-flowers made by the Italian peasantry to adorn images of saints. I believe that in these there is a little vinegar mixed. They are quite wax-like. The bread used should be soft household bread, of course well kneaded with the acid and colours. Bread-paste would probably combine well with indiarubber in solution.

Of late, German illustrated newspapers have published patterns of small ornamental dishes made of dough or bread, intended to receive conserves of fruit and other edibles--the dishes themselves not being intended to be eaten.

Soft bread with a little varnish or any ordinary gum and a little glycerine, well worked, makes an admirable filler for cracks in wood. Combined with any gum, or even with tragacanth or peach or cherry gum, and lamp-black (or liquid Indian ink), it forms a cement which resembles ebony. The more thoroughly it is macerated the harder it will be. Casts of panels, &c., made with this are really beautiful. Rub with oil and the hand after it is quite dry. Add a few drops of glycerine and alum in solution to prevent cracking, or, better, a _little_ indiarubber. Soft rye bread hardens to a rather tougher cement than wheat. Bread cement makes an admirable ground for gilding or painting. Bread macerated with lime and white of egg forms a very hard composition like ivory. Bread, glue, and glycerine, _ditto_.

HORSE-CHESTNUT PASTE.--This is called a cement, but it is properly a paste like that of flour. Horse-chestnuts are generally neglected, but they can be profitably utilised for paste, which admits of the same combinations as flour.

WASTE TEA-LEAVES from which the tea has been extracted can be macerated with gum and treated as rose-leaves to form artificial ebony. Carefully separate all the hard portions.

GUM FOR GENERAL USE, like gum-arabic:--

Common sugar, by weight 12
Water 36
Slacked lime 3

Stir the lime into the warm solution of sugar and water. Keep it boiling and stir it often for one hour. Pour off the liquid from the lees of the lime. This gum also admits of modifications. One of these is the well-known SYNDETIKON, which is made as follows:--To fifteen parts of the sugar and lime solution add three of good glue, leaving them to soak for twenty-four hours; warm gradually, and frequently stir, till the glue is dissolved. Then let it boil for a few minutes. This makes a good plain cement, which serves to unite paper, leather, glass, or porcelain. It, however, spots or changes colour in paper, &c.

A GENERAL CEMENT, which may be used for joining metal and glass, stone, tiles, &c., is thus made:--

Plaster of Paris 21
Iron filings 3
Water 10
White of eggs 4

THE GENERAL MENDING CEMENT so commonly sold consists of nothing but--

Gum-arabic 1
Plaster of Paris 3

This must be mixed with water when used. It does not, however, resist the action of hot water.

A CEMENT WHICH RESISTS ACIDS is made as follows:--Indiarubber is dissolved in double its weight of linseed-oil, and kneaded to a dough with white bolus. Should the cement harden too quickly, add to it a little litharge.

INDIARUBBER CEMENT FOR CHEMICAL APPARATUS:--

Indiarubber 8
Tallow 2
Linseed-oil 16
White bolus 3

This does not resist high temperature, but is good against acids.

SCHEIBLER’S CEMENT FOR CHEMICAL APPARATUS:--

Gutta-percha 2
Wax 1
Shellac 3

SOREL’S CEMENT.--This consists of oxide of zinc combined with its chloride. The chloride of zinc is in a heavy, syrupy form, which, combined with the white oxide, sets very hard. It is chiefly used for filling teeth, but is also applicable to making medallions and other objects of art. For this latter purpose it is mixed with powdered chalk, pulverised glass, &c. The process of preparing and combining the ingredients of this cement is, however, so tedious that it is most unlikely that the ordinary repairer will care to attempt it; the more so as there are many preparations far superior to it.

GLUE FOR TAPESTRY, &c.:--

Flour-paste 100
Alum water 3
Dextrine-paste 5

This may also be applied in many ways.

TO LUTE STILLS, &c.:--

Glue in powder 20
Flour 10
Bran 5

To be well mixed with water.

As alum cannot be affected by petroleum, it is used to fasten rings to petroleum-lamp holders. These are lined with alum which has been melted by heat. Alum melted forms a strong cement for glass and metal.

PASTE FOR WALL-PAPER.--Ten parts of flour are made into common paste; add one of glue boiled in hot water; add to the whole one-twentieth part of white of egg. This holds very firmly. Paste made with flour and gum-arabic, &c., does not mould or turn sour if it be mixed with a few drops of oil of cloves or carbolic acid.

CLAY MORTAR.--Where lime cannot be had, a very good mortar for chimneys may be made by mixing clay with common molasses. This is said (LEHNER) to resist the action of heat when well dried.

Another fireproof cement is made as follows:--

Clay 40
Flint-sand 40
Slacked lime 4
Borax 2

This is mixed with a very little water. It is used as a wash, and should, when dry, be heated by fire.

LOG CABINS and houses built with wood are, in America, often swarming with vermin to a degree which would seem incredible. In all such cases the joints and cavities should be well packed and plastered with cement--lime if possible--and then whitewashed. Rat-holes should be plugged with stones or gravel and then cemented.

ZEIODELETH.--Vessels of wood, iron, stoneware, or of moulded cement, are often eaten away by the action of acids and alkalies. To prevent this they are in Germany coated with a composition called _Zeiodeleth_. In its simplest form this is simply sulphur mixed with _very finely_ sifted flint-sand, or else ground glass, chinaware, or stone. Of this thin plates are also made to coat such vessels, or even to form them.

MERRICK’S ZEIODELETH:--

Sulphur 20
Glass-powder 40

BÖTTGER’S ZEIODELETH (LEHNER):--

Powdered flint 90
Graphite 10
Sulphur 100