(9) J. W. B. desires a recipe for some fire‐extinguishing liquid. A. One of the best solutions for the extinction of incipient fires consists of crude calcium chloride 20 parts, salt 5 parts, dissolved in water 75 parts. Keep at hand, and apply with a hand pump.
(10) G. H. A. says: I have lately made a workshop of an upper room, and have put in a lathe, boiler, and engine of a total weight of 2,400 pounds, resting upon 3 joists 3 inches by 9 inches by 16 feet 0 inches. Will it strengthen the floor sufficiently to enable it to carry the increased weight if I bolt three 3 inch by 8 inch joists to the existing ones? A. You had better use 4 inch by 8 inch joists bolted with ⅜ inch bolts about 10 inches apart. Take care to provide solid bearings for your new joists, wedging the ends up with tiles in cement.
(11) W. A. writes: I have noticed in your issue of the Scientific American, at various times, the receipt for making a printing machine called the hektograph. You also gave a recipe for making a black ink to be used with the same. I have tried both, but I find a great difficulty in gaining a success. I have tried the process for the ink in the manner you describe, but I fail to produce any copies. Ink is prepared with nigrosine. It will not create a bronze. Would you therefore kindly direct me in the right direction, that is to say, to get a black ink that can be used by the hektograph? A. The ink you desire is made by dissolving soluble nigrosine (aniline black) in 5 to 7 parts of water. It should be a saturated solution and rather thick. For use on the hektograph it is best to use a purple ink. See “The Copying Pad,” etc., contained in Scientific American Supplement, No. 438.
(12) A. C. R. writes: Can you recommend me a good rubber cement? I wish to cement leather together, the cement to be waterproof, to resist oil, and the leather to retain its elasticity after pressing. A. Dissolve gutta percha in bisulphide of carbon; shave off the edges of the leather, and pour on the cement; allow to evaporate to dryness. Then put the two faces together, previously heating thoroughly, and press until cool.
(13) G. F. asks the best kind of a vessel to make liquid gold in, for potter’s use. A. Either a glass or a porcelain vessel will answer.
(14) W. J. M. asks how papier mache is made to stand the action of water. A. Coat with a mixture made by fusing together equal parts of pitch and gutta percha, to which is added two parts of linseed oil containing five parts of litharge. Continue the heat until the ingredients are uniformly commingled, and apply warm.
(15) J. D. & Co. ask a process to prevent the smuts from escaping in the air from a lampblack house. A. Carry the outlet of your lampblack chamber to one side and into the top of a vertical shaft, where place a rose jet of water. Have the water drop vertically in an even spray, so as to produce a draught down the shaft. The water will gather the waste lampblack, which can be either utilized or run into the sewer. A vent at the bottom of the shaft may connect with a chimney or into the open air. A pump or city water supply will be required.
(16) W. D. G., Jr., asks how large a main pipe will be required to supply 6 hydrants and 50 dwelling houses, the water to be brought 1 mile with a 70′ head; the hydrants to be used with a 1″ nozzle, and there being no probability of more than two being required at a time? A. About a 6″ pipe; a smaller one would not give the desired pressure for hydrant uses.
(17) S. M. writes: Can you give a formula for a brilliant waterproof finishing polish to be used on veneer after it is rubbed down with pumice stone and water? The polish to be applied the same as French polish. Use linseed oil 1½ pounds, amber 1 pound, litharge 5 ounces, white lead, pulverized, 5 ounces, minium 5 ounces. Boil the linseed oil in an untinned copper vessel, and suspend in it the litharge and minium in a small bag, which must touch the bottom of the vessel. Continue the boiling until the oil has acquired a deep brown color, then take out of the bag and put in a clove of garlic; this is to be repeated 7 or 8 times, the boiling being always continued. Before the amber is added to the oil it is to be mixed with 2 ounces linseed oil and melted over a fire that is well kept up. When the mass is fluid, it is to be boiled and stirred continually for 2 or 3 minutes; afterward filter the mixture, and preserve it in bottles tightly corked. When this varnish is used, the wood must be previously well polished and covered with a thin coat of soot and spirits of turpentine. When the coat is dry some of the varnish may be applied, which should be equally distributed on every part with a small, fine sponge. This operation must be repeated four times, being always careful that each coat will be well dried first. After the last coat of varnish, the wood must be dried in an oven and afterward polished.
(18) G. P. writes: We want some plan to prevent the noise or work of our lodge room (I.O.O.F.) from being heard in the room below; we have a good floor and carpet, good partitions, walls plastered, etc., but are willing to go to quite an expense to remedy the present defect on this score. A. Probably you have no deafening under the floor. In such case there are only two ways that we can suggest for your trouble: To take up the floor and put in a plaster deafening between the seams. Next, to take up the carpet and lay two thicknesses of roof felting or paper boards (book‐binders’ boards might do, or paper carpet lining). Then lay battens across the floor, and a new floor on the battens. Do not nail the battens to the old floor. Then lay the carpet lining and the carpet on the lining.