(1) The best packing for cast-iron socket hot-water pipes is yarn and white and red lead (best white hemp yarn preferred), used in the following manner: - First caulk home about one round of yarn, then put in a ring of red and white lead about 3/4-in. diameter, then caulk home another rouud of yarn, and continue this alternately until the socket is filled up to about 1/4 in., then finish off with wet iron borings, with a small quantity of sal-ammoniac in it (1 oz. to 1/4 cwt. is sufficient); let the yarn be in one continuous length from the commencement to finish. Some use all borings and sal-ammoniac, but this is not safe, as the rusting of the borings expands so much that it often bursts the sockets of pipes. (2) 2 parts of ordinary well-dried powdered loam and 1 part of borax are kneaded with the requisite quantity of water to a smooth dough, which must be at once applied to the joints. After exposure to heat, this cement adheres even to smooth surfaces so firmly that it can only be removed with a chisel. (3) Mix 430 parts in weight of white lead, 520 of powdered slate, 5 of chopped hemp, and 45 of linseed oil.
The two powders, and the hemp cut into lengths of 1/4 - 5/16 in. are mixed, and the linseed oil is gradually added; the mass is kneaded till it has assumed a uniform consistency. This cement is said to keep better than the ordinary red lead cement.
(18) A permanent and durable joint can, it is said, be made between rough, cast-iron surfaces by the use of asbestos with sufficient mixed white lead to make a very stiff putty. This will resist any amount of heat, and is unaffected by steam or water. It has been used for mending or closing cracks in cast-iron retorts that were used for the distillation of oil and gas from cannel coal. The heat being applied to the bottom of retorts and the temperature of iron maintained at a bright red heat, after a time the bottom of the retort would crack, the larger portion of the crack being downward towards the fire. The method employed was to prepare the mixture, and place on top a brick, then place the brick on a bar of iron or shovel and press the cement upward to fill the crack in the iron, holding it for some time until it had penetrated the cavity, and somewhat set. Of course, during this operation, the cap was removed from the retort, so that no pressure of gas or oil forced the cement outward until set. (19) Stir into 1 part of sweet oil and 1 part of molasses, 1 part each of barytes, Venetian red, litharge, and red lead, and 1 1/2 part each of plumbago, Paris white, and yellow ochre.
It takes several hours to prepare, but will remain plastic for years.
(22) Lehner publishes the following formula for making a liquid paste or glue from starch and acid: - Place 5 lbs. of potato starch in 6 lbs. (3 quarts) of water, and add 1/4 lb. of pure nitric acid. Keep it in a warm place, stirring frequently for 48 hours. Then boil the mixture until it forms a thick and translucent substance. Dilute with water, if necessary, and filter through a thick cloth. At the same time another paste is made from sugar and gum-arabic. Dissolve 5 lb. gum-arabic and 1 lb. sugar in 5 lb. of water, and add 1 oz. of nitric acid and heat to boiling. Then mix the above with the starch paste. The resultant paste is liquid, does not mould, and dries on paper with a gloss. It is useful for labels, wrappers, and fine bookbinders' use. (23) Paper pasted, gummed, or glued on metal, especially if it has a bright surface, usually comes off on the slightest provocation, leaving the adhesive material on the back of the paper, with a surface bright and slippery as ice. The cheaper description of clock dials are printed on paper and then stuck on zinc; but for years the difficulty was to get the paper and the metal to adhere.
It is, however, said to be now overcome by dipping the metal into a strong and hot solution of washing soda, afterwards rubbing perfectly dry with a clean rag. Onion juice is then applied to the surface of the metal, and the label pasted and fixed in the ordinary way. It is said to be almost impossible to separate paper and metal thus joined. (24) Dissolve 1 oz. gum tragacanth and 4 oz. gum-arabic in 1 pint water; strain, and add 14 grs. thymol suspended in 4 oz. glycerine; finally add water to make 2 pints. This makes a thin paste suitable for labelling bottles, wooden or tin boxes, or for any other purpose paste is ordinarily called for. It makes a good excipient for pill-masses, and does nicely for emulsions. The very small percentage of thymol present is not of any consequence. This paste will keep sweet indefinitely, the thymol preventing fermentation. It will separate on standing, but a single shake will mix it sufficiently for use. (25) 4 oz. rye flour, 1/2 oz. powdered gum acacia. Rub to a smooth paste with 8 oz. of cold water, strain through a cheese cloth, and pour into 1 pint of boiling water. Continue the heat until thickened to suit.
When nearly cold add: -
1 oz. glycerine, 20 drops oil cloves. This is suitable for tin or wooden boxes or bottles, and keeps sweet for a long time. (26) 4 oz. rye flour, 1 pint water, 1 dr. nitric acid, 10 minims carbolic acid, 10 minims oil cloves, 1 oz. glycerine. Mix the flour with the water, strain through a cheese cloth, and add nitric acid. Apply heat until thickened to suit, and add other ingredients when cooling. This is suitable for bottles, tin or wooden boxes, and will not spoil. (27) 8 parts dextrin, 2 parts acetic acid, 2 parts alcohol, 10 parts water. Mix dextrin, water, and acetic acid to a smooth paste, then add the alcohol. This makes a thin paste, and is well suited for labelling bottles and wooden boxes but is not suitable for tin boxes.
(2) According to Dr. L. Heydenreich of St. Petersburg, the best cover-glass should be: - 1st. Absolutely hermetic, and should not, under any circumstances, require renewal every year. Two or three coats of the cement, applied at short intervals after an object is mounted, should permanently secure and preserve the object. 2nd. It should be as hard as glass, or, if possible, harder. 3rd. It should not crack nor become' detached, and should be so solidly adherent as to be less likely to break than the glass to which it is attached; and 4th. It should be insoluble in water or glycerine, or in any liquid used as an immersion medium with objectives. Notwithstanding the large number 'of cover-glass cements already known and in use, he thinks another should be sought for - one which shall conform to the foregoing requirements. We have commercial varnishes, which are very hard and durable. Some of them, used in the finishing of carriages, are found, after the lapse of a year, to be in the same condition as when first applied. The varnish used on tin pans in albumen factories remains unchanged for a year, although subjected daily, for many hours, to a temperature of 100° R. (257° Fahr.) These and similar varnishes are made of resins, copal, or amber.