( 346 ) 



to which we must reject the observation at - 255°. 07 yielding 

 0.02314 where A' gives 0.01974 and B' 0.01984. 



§ 8. Carbon <///</ constantin. Besides the variations of the metals 

 investigated we have ') also investigated to 262° the variations of 



resistance of carbon and constantin. 



§ i». Alloys of An and Ac/. One of us .1. Ci.u lias extended the 

 investigation treated of in the preceding sections to different alloys 

 of gold and silver and has added the determination of the electro- 

 motive force of the thermo-elemenl gold-silver. This investigation 

 showed that the theorie- of Rayleigh and Liebenow about the thermo- 

 electric origin of the difference in resistance introduced in § 1 the 

 additive resistance of M \ttiiikskn ■ ), must be rejected. For the value 

 p, introduced in § I, the observations mentioned yield with a gold 

 wire of 1 m. in length and 1 mm. 1 in section per volume procent 

 silver added 



p = 0.00360 i-i. 



Mathematics. "Chi certain twisted secties". By Mr. M. Stuyvaert 

 at Grhent. Communicated by Prof. -Ian de Vries). 



(Communicated in the meeting of October 31. 1908). 



Prof. .Ian DE Ykiks has had the goodness to send us an interesting 

 paper which he has published in the Proceedings of the Koninklijke 

 Akademie van Wetenschappen at Amsterdam, entitled "On hoisted 

 curves of genus two" 26 May 1908). 



The greater part of this paper is concerned with twisted curves 

 of* genus two and of order live or six. We shall here offer a rapid 

 survey of the results to be obtained when we apply to these curves 

 the elementary properties of matrices, a subject upon which we have 

 recently published a volume: Cinq Etudes de Geometrie analytique 

 (Grhent, van Goethem, 1908). We shall here occupy ourselves only 

 with curves of order six and we shall content ourselves with observing 

 that the quintic can be treated by analogous but more simple pro- 

 ceedings. 



l ) Gf. footnote 1 to § 7. 



-I With regard to the deviation trom Matthiesen's theorem at liquid hydrogen 

 temperatures, mentioned sub § 1. we also refer to the publications mentioned in the 



footnote 1 to § 7. 



