Heavy chemicals in the United States

C U R R E N T TOPICS Heavy Chemicals in the United States. ANON. (Oi/, Paint and Drug Reporter, May, I914.)--The imports of bleaching powder in I9I 3 amounted to 30,800 short tons, compared with 37,I2O tons in I912; 41,45 o tons in I9I I, 50,500 tons in I9xo , 45,70o tons in i9o9, and 55,6oo tons in 19o8. Imports from England have decreased from about 3o,o0o tons in I9Ii to 22,25o tons in 19.13, while Germany supplies about 6ooo tons annually. The output of American works amounts to about 90,0oo tons, of which about 3o,o0o tons are exported. The output of caustic soda in I9I 3 reached about I9O,OOO, of wlfich about 2o,0oo tons were exported. The exports to Canada average about 15,ooo to 2o,ooo drums per year. Arsenic was imported to the amount of 413o tons in I9IO, which dropped to 334o tons in I9I 3. Imports from Europe have practically ceased, the only material source of foreign suppl] being Canada. The output last year in the United States was 2375 tons, and in I9!2, 3141 tons.

Recording of Wireless Signals by Means of the Telegraphone. P. DOSNE. (Comptes Rendus, clviii, 473.)--The recording of wireless signals on a telegraphone wire or plate, as proposed by Simon and Reich, has been carried out by the author. A sound reinforcer constructed on the principle of that of Berget and Allard has its circuit interposed between the crystal detector employed and the telegraphone recording electromagnet.

The Most Powerful Magnet. ANON. (Sci. Amer., cx, No. 23, 459.)--Probably the strongest electromagnet is produced by the new method successfully applied by Profs. Perot and Deslandres. Their idea is to take one of the strongest electromagnets of laboratory type with pointed pole pieces which already give a high value of the magnetic field, and then to put an extra coil around the air-gap between the poles so as to add considerably to the field. Such coil is made of thin copper strip and is cooled down as low as - - 3°0 C. by a current of oil, so that a remarkably heavy current can be put into the coil without burning it; e.g,, it will stand a current density of 18oo amperes per square mm., using a 0.2 ram. strip. Such a coil is put on a Weiss electromagnet which carries the usual coils and gives 4I,OOO gauss for the magnetic field strength. Putting on the 3o,ooo amp&re-turns of the new coil brought up the field strength to 51,ooo gauss, and it was only the lack of current supply that prevented running as high as probably 6o,ooo gauss, so that a most powerful field can thus be obtained. 375