Cement for cracked bottles. Select a cork which will fit the bottle air-tight and place it loosely upon the bottle, and heat the latter gradually to at least 212° F. Then press the cork down and apply a thick solution of water-glass to the cracks. In cooling, the air in the bottle contracts strongly, and the pressure of the exterior air drives the water-glass with great force into the cracks closing them entirely so that they cannot be detected.
Cement for glass and porcelain. Stir quickly together 10 parts of elutriated glass meal, 20 of powdered fluor spar, and 60 of water-glass solution, and apply the homogeneous paste at once. In a few days the cement will be so hard that the cemented vessels can be heated without danger.
Cement for hydraulic works. Finely powdered cement, and solution of water-glass. Mix the two bodies quickly together.
As this cement hardens very quickly, it should be used fresh. It hardens under water, and is therefore excellent for hydraulic works. The stones should be coated with a solution of water-glass before applying the cement.
Cement for uniting metals. A strong cement, which hardens rapidly, is made by stirring the finest whiting in a solution of soda-glass of 33° B., made so as to form a plastic mass. This can be readily colored to any desired shade. The addition of sifted sulphide of antimony gives a black cement, which by polishing acquires a metallic lustre; iron filings render it grayish-black; zinc dust turns it green, but after polishing, it appears like metallic zinc, and may be employed for the permanent repair of zinc ornaments, etc. Carbonate of copper imparts a light green shade. Other additions may be made, as oxide of chrome for dark green, cobalt blue for blue, red lead for orange, vermilion for scarlet, carmine for violet, etc.
Cement for tightening joints of pipes exposed to a red heat. Mix 80 parts of pyrolusite, 100 of zinc white, and 20 of water-glass.
This cement fuses at a temperature not too high, and then forms a glass-like mass which adheres very firmly and closely.
Cement for marble and alabaster. The point of fracture of articles cemented with the following mixture is difficult to find, and the cemented place is much stronger than the material itself. Mix 12 parts of Portland cement, 6 of slaked lime, 6 of fine sand, and 1 of infusorial earth with sufficient water-glass to form a thick paste. The article to be cemented need not be heated. It hardens in twenty-four hours.
GLYCERINE AND GLYCERINE CEMENTS.
Commercial glycerine is a yellowish or nearly colorless and more or less viscid liquid having an intensely sweet taste. In combination with lead oxide and intimately worked into it, by heating and stamping, it furnishes very strong and durable cements deserving general introduction, though thus far they have been but little used.