Of the Force and Temperature of Steam in Atmospheres. TO WRITE ON SILVER WITH A BLACK WHICH WILL NEVER GO OFF.Take burnt lead and pulverize it. Incorporate it next with sulphur and vinegar, to the consistency of a painting color, and write with it on any silver plate. Let it dry, then present it to the fire so as to heat the work a little, and it is finished. TABLE Of the Heating Power of various Combustible Substances, exhibiting the utmost Quantity of Water evaporated by the Given Weights, and the smallest Quantity of Air capable of producing Total Com TO ESTIMATE DISTANCE.-Observe how many seconds elapse between a flash of lightning and the thunder, and multiply them by 1142, the number of feet sound travels in a second, the product will be the distance in feet. The same process may be applied to the flash and report of a gun, or any other sound, provided we can ascertain the time at which it is produced, and the interval that elapses before it reaches the ear. Illustration. Saw a flash of lightning five seconds before I heard the thunder: required the distance. In the absence of a watch, the pulsations at the wrist may be counted as seconds, by deducting one from every seven or eight. PRISMATIC DIAMOND CRYSTALS FOR WINDOWS.-A hot solution of sulphate of magnesia, and a clear solution of gum arabic, mixed together. Lay it on hot. For a margin or for figures, wipe off the part you wish to remain clear with a wet towel. PERFECTLY BLACK HARD GLASS.-Plain paste, 600 parts; zaffre, 3 parts; manganese, 3 parts; iron, 3 parts. 817 3 0 6 x 111 1 6 9 × 3 × 4 × 4 4122 6 4 1 8 1 3 731 53 21 31112111 61413 0 6 x 1 9 1 6 8×31 21 4 2 2 1 8 24 23 21 61 8121221 61 873 3 2162 7 × 3 4 × 39 9 × 4 9 × 4 x 512 × 4 x 512 × 4 x 5 12 x 41 21 12 31 8 5 6 316 191 x 720 ×7 13 16 5 5413 04 721 Dia. of piston-rod, the dia. of cyl. Air-pump rod iron the dia. of air-p. Side-rods full of piston-rods. |