456 Miscellaneous Intelligence, 



antimony and the poles of a magnetic needle, is a caseof this gehe» 

 ral law, and is not due to magnetism. Nor is it magnetism which 

 occasions the direction of needles formed of other substances than 

 iron, announced lately by M. Becquerel. 



ii. A very marked attraction may be observed between a cold 

 and a heated body, or between two bodies of different temperature, 

 whether screens be interposed or not. 



iii. The metallic plates in the Cabinet de Physique de Paris, 

 intended for the repetition of M. Arago's experiments on magnetism 

 by rotation, contain more or less of iron capable of attracting a 

 very mobile magnetic needle. These plates, and those of M. Arago, 

 were made by the same person and from the same materials. 



iv. I believe that, in many cases, results obtained without the 

 appreciable developement of magnetism or electricity, have been 

 attributed to these powers ; and from well-proved experiments I 

 shall deduce new results relative to the diurnal variation of the 

 needle, the direction of the plumb-line and the density, temperature 

 and attraction of the planetary masses. — Bull. Univ. A. viii. 287. 



7. On the Magnetic Effects of Metals in Motion. — M. Seebeck has 

 endeavoured to determine the effects of various metals in diminish- 

 ing the oscillations of a magnetic needle 2^ inches in length, and 

 suspended by a silk fibre three lines distant from and above the 

 plates. The oscillations were counted from an amplitude of 45*^ 

 to 10°. 



116 oscillations above a plate of marble 



112 layer of mercury 2 lines in thickness. 



106 plate of bismuth 2 „ 



94 platina 0.4 ,, 



90. antimony 2.0 „ 



89 lead 0.75 



89 gold 0.2 



71 zinc 0.5 „ 



68 tin 1.0 



62 brass 2.0 



62 copper 0.3 „ 



55 silver 0.3 



6 >, iron 0.4 „ 



It is also stated that he has found, from experiments, that by 

 alloying such metals as are magnetic, like iron, nickel, and cobalt, 

 with other metals, which like antimony diminish the magnetic force, 

 alloys are obtained entirely neutral in their effects ; thus the alloys 

 formed by four of antimony with one of iron, three of copper with 

 one of antimony, and two of copper with one of nickel, produce no 

 diminution of the number of oscillations, these amounting to 116 as 

 with the plate of marble. These three alloys are, therefore, the best 

 for the manufacture of compasses, those of copper and nickel being 

 the most malleable. — Annal. des Fhy. 1826. Bull. Univ. A. viii. 136, 



