General Morin believes this alloy to be a perfect chemical combination, as it exhibits, unlike the gun metal, a most complete homogeneousness, its preparation being also attended by a great development of heat, not seen in the manufacture of most other alloys. The specific gravity of this alloy is 7.7. It is malleable and ductile, may be forged cold as well as hot, but is not susceptible of rolling; it may, however, be drawn into tubes. It is extremely tough and fibrous. Aluminum bronze, when exposed to the air, tarnishes less quickly than either silver, brass, or common bronze, and less, of course, than iron or steel. The contact of fatty matters or the juice of fruits does not result in the production of any soluble metallic salt, an immunity which highly recommends it for various articles for table use. The uses to which aluminum bronze is applicable are various. Spoons, forks, knives, candle-sticks, locks, knobs, door-handles, window fastenings, harness trimmings, and pistols are made from it; also objects of art, such as busts, statuettes, vases, and groups. In France, aluminum bronze is used for the eagles or military standards, for armor, for the works of watches, as also watch chains and ornaments. For certain parts, such as journals of engines, lathe-head boxes, pinions, and running gear, it has proved itself superior to all other metals. Hulot, director of the Imperial postage stamp manufactory in Paris, uses it in the construction of a punching machine. It is well known that the best edges of tempered steel become very generally blunted by paper. This is even more the case when the paper is coated with a solution of gum arabic and then dried, as in the instance of postage stamp sheets. The sheets are punched by a machine the upper part of which moves vertically and is armed with 300 needles of tempered steel, sharpened in a right angle. At every blow of the machine they pass through the holes in the lower fixed piece, which correspond with the needles, and perforate five sheets at every blow. Hulot now substitutes this piece by aluminum bronze. Each machine makes daily 120,000 blows, or 180,000,000 perforations, and it has been found that a cushion of the aluminum alloy was unaffected after some months' use, while one of brass is useless after one day. Various formulæ are given for the production of alloys of aluminum, but they are too numerous and intricate to enter into here. * * * * * DETERMINATION OF POTASSA IN MANURES. By M.E. DREYFUS. The method generally adopted for the determination of potassa in manures, i. e., the direct incineration of the sample, may in certain cases occasion considerable errors in consequence of the volatilization of a portion of the potassium products.