(ii: 62; v. 13.)
Make a concentrated solution of silicate of soda, and form a paste with powdered glass. This simple mixture will sometimess be found invaluable in the operations of the laboratory where a luting is required to resist the action of acid fumes. (See also ii 62, v. 13.)
(a) Take 1 gill of plaster of Paris, 1 gill of litharge, 1 gill of fine white sand, 1/3 of a gill of finely-powdered rosin. Mix well, and bottle and cork it until wanted for use, then mix it with boiled oil and dryers until as thick as putty. Mix the cement only in small quantities, as it dries quickly.
(a) A solution of glue, 8 oz. to 1 oz. of Venice turpentine; boil together, agitating all the time, until the mixture becomes as complete as possible, the joints to be cemented to be kept together for forty-eight hours if required.
Dissolve 5 or 6 bits of gum mastic, the size of a large pea, in as much spirits of wine as will suffice to render it liquid; in a separate vessel dissolve as much isinglass (previously softened in water, though none of the water must be used) in rum, or other spirit, as will make a 2-oz. phial of very strong glue, adding two small pieces of gum ammoniacum, which must be rubbed or ground till they are dissolved; then mix the whole with a sufficient heat. Keep it in a phial closely stopped, and when it is to be used, set the phial in boiling water. The preceding is also effectual in uniting almost all substances, even glass to polished steel. (See also ii. 67.)
Finest pale orange shellac, broken small, 4 oz.; rectified spirit (the strongest, 58 o.p.) 3 oz.; digest together in a corked bottle in a warm place until dissolved; it should have the consistence of treacle. For wood, glass, ivory, jewellery, and also fancy works. (See also ii. 72, v. 18.)
(a) Rosin, 4 parts, to 1 part beeswax and 1 part of brick-dust, or plaster of Paris.
(6) 16 parts rosin, 16 hot whiting, and 1 wax.
(c) Pitch, 4 parts; rosin, 4; tallow, 2; and brick-dust, 2.
Bisulphide of carbon, 4 oz.; fine rubber in shreds, 1 oz.; isinglass, 2 dr.; gutta-percha, 1/2 oz.; dissolve. Used for cementing leather or rubber. The parts to be joined must be coated thinly with the solution, and allow a few minutes to dry, then heat to melting; place the parts together and well hammer the air bubbles out. (See also ii. 74, v. 17.)
A good cement for chemical and electrical apparatus may be prepared by mixing 5 lb. of rosin, 1 lb. of wax, 1 lb. of red ochre, and 2 oz. of plaster of Paris, and melting the whole with moderate heat. (See also ii. 70.)
(a) Mix ground white-lead with as much finely-powdered red-lead as will make it the consistence of soft putty.
(6) Mix equal parts of white-lead and red-lead, and add as much boiled linseed oil as is required to give it the proper consistence; or boiled linseed oil and red-lead mixed into a putty. These cements are used for making metallic joints sound. (See also ii. 74.)
(a) To 4 or 5 parts of clay, thoroughly dried and pulverised, add 2 parts of fine iron filings free from oxide, 1 part of peroxide of manganese,1/2 part of sea salt, and 1/2 part of borax. Mingle these thoroughly and render them as fine as possible, then reduce them to a thick paste with the necessary quantity of water, mixing thoroughly well. It must be used immediately. After application it should be exposed to heat, gradually increasing almost to a white heat. This cement is very hard, and presents complete resistance alike to a Ted heat and boiling water.
(b) To equal parts of sifted peroxide of manganese and well-pulverised zinc white, - add a sufficient quantity of commercial soluble glass to form a thin paste. This mixture, when used immediately, forms a cement quite equal in hardness and resistance to that obtained by the first method. (See also ii. 74.)
(a) Mix thoroughly 2 parts good clay, 8 parts sharp washed sand, 1 part horse-dung, then temper like mortar.
(c) Mix dry clay in powder with drying oil into a thick paste. The part to which this is applied must be clean and dry..
(d) Plaster of Paris mixed with water, milk, or weak glue. Both (c) and (d) stand a dull red heat.