146 Dr. W. Flight on two new Amalgams, 



battery- and telephone-circuits) is no longer zero. If the 

 iron were instantaneously magnetizable, one ought to be able 

 to balance its effect by moving the other pair of coils a little 

 nearer together, so as to make M zero again. But as the magne- 

 tization of iron always takes time, this is not completely pos- 

 sible, because, though M may be made zero at any one instant, 

 it will not remain so during the period of variation of the cur- 

 rent. As regards pitch, the rustle produced by iron wire 

 should agree with that produced by a shift of the coils, both 

 being duller than that produced by a piece of copper. Of 

 course if a mass of iron be inserted, the effect will be compo- 

 site, secondary currents being induced in it which give rise 

 to tertiary currents in the telephone-circuit. But this effect 

 is feeble as compared with the magnetic effect. 



In measuring the conductivity of a metal or of an electro- 

 lytic solution by means of the induction-balance, care must 

 be taken that it is not magnetic ; or erroneous results will be 

 obtained. The conductivity effect and the magnetic effect will 

 tend partially to destroy each other ; for though the effect of 

 a piece of copper cannot be completely balanced by introdu- 

 cing a scrap of iron into the same pair of coils, it can partially, 

 just as it might partially by shifting the coils (§ 18). 



It would be very interesting to observe an opposite effect 

 with a diamagnetic body — say a large bundle of thin bismuth 

 wires insulated from each other ; but it would not be easy to 

 make sure of the correctness of the observation. 



XVIII. Examination of two new Amalgams, and a Specimen 

 of Native Gold. By Walter Flight, D.Sc, of the Mineral 

 Department of the British Museum*. 



A SPECIMEN of "native silver " from Kongsberg proved, 

 on analysis, to be an amalgam, and, as it appears to me, 

 to be an amalgam new to science. The composition of the 

 specimen in question was found to be : — 



Silver . . 75*900 



Mercury . 23-065 



Insol. part . Q'490 



99-455 



Z^°=0-70. 

 108 



23-065 



100 



:0'23. 



These numbers indicate the formula Ag 3 Hg as that of the 

 amalgam, or a composition the converse of that of the amal- 



* Communicated by the Crystallological Society. 



