250 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



causing the drop to contract by an altered surface tension; 

 and reoxidation outside of the drop, causing it to expand 

 again over the surface. 



Beetz, from his experiments on the comparative value of 

 the thermopiles of Noe and of Clamond,as modified by Koch, 

 concludes in favor of the latter. The objection that it re- 

 quires a little time to be heated he regards of little impor- 

 tance, but once in action it continues remarkably constant, 

 both as regards its electromotive force and its resistance. 

 Since with the same number of pairs the Noe* pile gives the 

 greater electromotive force, the utility of the Clamond bat- 

 tery is quite equal, from the facility with which the number 

 of pairs may be increased. He suggests that the burner of 

 the latter should be improved. 



Gore has communicated to the Royal Society a paper on 

 the thermo-electric properties of liquids, in which he de- 

 scribes a new form of apparatus he has contrived for the in- 

 vestigation, and gives the results of his observations made 

 with it. He shows that the electric currents obtained were 

 produced neither by chemical action nor by a temporary 

 dissociation of the liquid, nor by the action of gases oc- 

 cluded in the metals; but they owe their origin solely to 

 the heat, which disappears in producing them, and are thus 

 true thermo-electric currents of liquids. He concludes as 

 probable that when a metal is immersed in a liquid, heat re- 

 sults. His experiments suggest the construction of a new 

 thermo-electric motor. 



3. Electrical Measurements. 



GaifFe has contrived two simple forms of galvanometer, 

 one for measuring electromotive force directly, and the oth- 

 er for measuring current strength. In the former the coil 

 has a high resistance (about 3000 units of the British Asso- 

 ciation committee), so that the resistance of the rheomotor 

 may be neglected in comparison, and the deflections of the 

 needle be sensibly proportional to the electromotive forces. 

 By means of two additional resistance coils the resistance 

 may be increased 10 and 50 times. The circle is graduated 

 empirically into GO divisions, each of which represents one 

 tenth of a volt when the galvanometer resistance alone is 

 used. Electromotive forces from 0.1 to 150 volts may thus 



