48 Electromotive and Thermoelectric Forces of Metallic Alloys, 



volume of these measures, which were made of glass, was most 

 accurately determined by F. Rudberg in the year 1833 at 100 

 cubic decimal inches ; M. Edlund, however, found the volume 

 of all three vessels perceptibly less, thereby proving a perma- 

 nent structural alteration in the glass, which in twenty-four 

 years had brought about a sensible lessening of the volume of 

 these measures. Finally we will mention the transformation of 

 the artificially produced monoclinic crystals of sulphur into an 

 aggregate of minute rhombic crystals, the passing of arsenic acid 

 from the amorphous state into the crystalline form, and other 

 phenomena of this kind well known in chemistry. 



It is probable that the bismuth-antimony alloys are subject to 

 a change similar to that undergone by the bismuth-tin alloys, 

 although the effect of it on the electromotive force may be too 

 little to become apparent during the proportionally brief time of 

 the present investigation. Whether all solid conductors are 

 thus altered when subjected to mechanical treatment, and to 

 what extent the alteration is accompanied by modifications of 

 their other physical properties (as density, capability of con- 

 ducting heat and electricity, &c), may be brought to light by 

 future inquiries. 



Supplement. — I take leave here to mention that General 

 Freiherr v. Wrede, of Stockholm, has recently discovered very 

 remarkable alterations of the length of a rod, 1 decim. long, of 

 the alloy 2 parts bismuth 1 part tin, as well as variations in its 

 expansion by heat*. With respect to variations of the resistance 

 to electric conduction of some alloys I made some experiments 

 in Bonn at the end of last summer (1872). Through the kind- 

 ness of Geheim-Rath Clausius I had the opportunity of using in 

 these experiments an excellent universal galvanometer by Sie- 

 mens. The results were : — The resistance of the alloy 2 parts 

 bismuth 1 part tin diminished in 21 days 0*064 of its original 

 quantity; that of the alloy 1 part bismuth 1 part tin, 007 in 9 

 days ; and that of the alloy 1 part bismuth 2 parts tin, 0*06 in 

 4 days. The velocity of the change had its greatest value im- 

 mediately after casting. The alloys 12 parts bismuth 1 part 

 tin, 1 part bismuth 5 parts lead, and 10 parts bismuth 1 part 

 antimony exhibited a pretty constant resistance to conduction, 

 since the variations did not amount to more than 1 per cent. 



* Kongl. Svenska Vet.-Akad. Handl. 1872. 



