666 
gold Rr=20.3 > Rr—s90, but for alloys with more than 2 °/, of silver 
by volume P27—20.3 < Rr=2090. 
The curve that represents the relation between the Harr coefficient 
R7—203 and the percentages of silver is of a shape analogous to that 
representing the conductibility or the temperature coefficient of the 
resistance as a function of percentages of silver. The curve for 
Rr=20.3 at first descends very rapidly for small admixtures of Ag; 
at higher concentrations it becomes flatter. 
The Harr coefficient Riso, is approximately a linear function 
Won a : : 
of the quantity “=""° for alioys with less than about 8°/, by 
EE =DE 
volume of Aq. 
The Hau. coefficient /7—s99 diminishes too, though much more 
slowly than R7=203, when the percentage of Ay increases. 
Physics. — “On the triple point of methane’. By C. A. CRoMMELIN. 
Comm. N°. 1316 from the physical Laboratory at Leiden. 
(Communicated by Prof. H. KAMERLINGH ONNES). 
The measurements made by Prof. Marniras, Prof. KAMERLINGH ONNES 
and myself on the diameter for argon‘) afforded an opportunity 
of determining the pressure and temperature of methane at its triple- 
point. For, when the cryostat was filled with liquid methane, and 
the pressure was reduced so as to give a temperature of about 
— 183° C. the methane was covered with a solid crust. A slight 
increase of the pressure caused the solid methane to spread itself in 
small pieces throughout the liquid. While these pieces were kept in 
constant motion through the liquid by means of the stirrer, the 
following triple point constants were observed : 
#= — 183.15 K. Pt Oem. 
On account of the manner in which these figures have been determined 
they must be considered to be very accurate. 
As far as I am aware there has, hitherto been only one other 
determination of these data — that of OrszewskKr ®) — who found 
¢—= — 185.°8 and p=8.0 em. 
*) Comm. No. 131a. 
*) K. Ouszewski, G. R. 100, page 940, 1885, 
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