146 ANNUAL OF SCIENTIFIC DISCOVERY. 



machinery became electrically charged. But the apparatus is simple and 

 cheap, and capable of working under atmospheric conditions which arrest the 

 action of our ordinary machines. 



ELECTRIC CONDUCTING TOWERS OF THE METALS OF THE ALKA- 

 LIES AND ALKALINE EARTHS. 



Dr. A. Matthiessen has made, under the direction of Prof. Kirchhoff, 

 of Heidelberg, a scries of experiments on this subject, the method of per- 

 forming which is fully described in the London, Edinburgh and Dublin 

 Philosophical Magazine, for February. The following are the results. The 

 temperatures are in centigrade degrees. 



The conducting power of silver at being = 100. 



That of Sodium at 21-7 = 37-43 



The potassium and sodium used, were commercial ; the others were ob- 

 tained electrotypically. Experiments were also made, and arc reported 

 in the original paper, on the variation of the conducting power by heat. 



In these results an interesting fact was observable, namely, that at some 

 distance from the point of fusion, as well in the liquid as in the solid state, 

 the decrements in the conducting power with the increase of temperature 

 were almost in proportion, but near the point of fusion the decrease in the 

 conducting power became much more rapid ; with sodium this change ap- 

 pears to be very sudden, whereas with potassium it seems gradual. This 

 difference in these metals corresponds with their different behavior in fusion ; 

 namely, potassium does not become suddenly liquid like sodium, but first 

 passes through a semi-fluid state. 



SIMULTANEOUS AND OPPOSITE ELECTRIC CURRENTS IN THE SAME 



WIRE. 



M. Pctrina has investigated this disputed phenomenon by means of the 

 reduction of temperature which Peltier discovered to take place when an 

 electric current passes from bismuth to antimony. A metallic bar of these 

 two metals soldered together in the middle, was introduced into the bulb of 

 an air-thermometer, and divided currents from the same battery carefully 

 equalized, were passed through it in opposite directions. In this case, if no 

 current passes, no effect should be produced ; but if both pass, since the 

 cooling effects are known to be much less than the heat produced by the 

 same current when passing in the opposite direction, the thermometer should 

 indicate such heat. In fact, no effect was produced when the currents were 

 equalized, and when they were allowed to be unequal, the heat was that due 

 to the difference of the currents. Cosmos. 



