158 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



THE INFLUENCE OF ARMATUKES UPON MAGNETS. 



Janiin, by very careful observation, has shown that the 

 placing of an armature on the end of a magnet brings about 

 a new distribution of the magnetic forces, but that the total 

 force is neither increased nor diminished ; the magnet itself 

 loses, but the armature gains magnetic force. 19 (7, VIII., 

 104. 



FORMATION OF NATURAL MAGNETS. 



Dr. Schonfeldt, of Dorpat, Russia, gives, in the Bulletin of 

 the Naturalists' Society of Moscow, an exhaustive treatise, 

 historical and otherwise, on the magnetic forces discoverable 

 in various kinds of matter. After o-ivino; numerous histor- 

 ical references, culled from the archives of China, Phoenicia, 

 Greece, Egypt, India, and elsewhere, and a very complete 

 account of the research of modern physicists, he proceeds to 

 give the results of the experiments made by himself His 

 first aim seems to have been to produce artificial magnets by 

 methods as nearly as possible in imitation of what might be 

 supposed to have been the processes that have obtained in 

 nature. He states that he filled a glass tube five inches 

 long and three fourths of an inch in diameter with pure iron 

 filings, after he had vret them with a thin solution of lime. 

 The ends of the tube were closed with glass stoppers. After 

 the contents had been exposed to a slight Avarmth for two 

 days, thereby becoming thoroughly dried, it was closely 

 wrapped around with insulated copper wire through which 

 a pretty strong current of electricity was allowed to pass. 

 In ten minutes, during which time the tube had become 

 slightly warm through the influence of the electric current, 

 it was removed from the spiral and cooled. For days and 

 days after that, whenever the tube was suspended by a 

 thread, it was found to be as magnetic as a strong magnet. 

 A considerable time after the tube was carefully broken and 

 separated from its contents, whereby there was obtained a 

 solid, pretty light, very active magnetic cylinder, in which 

 the iron filings had been in great part converted into oxide 

 of iron. Another cylinder, prepared in the same way and 

 broken into very small pieces, showed a similar magnetic po- 

 larity, which it even now preserves after a lapse of twenty- 



