( 429 ) 



and this is the more accurate foriuuhi, which has taken the place of 

 the simple rehition (3). 



III. We will now show, that tlic above formula qnantitalivelv 



yields the values, foujid by van Hkteren for 7\ in a satisfactorv manner. 



/dT\ .. , * 

 As — T- == ^0 '^A ^^ ni<"^v ho determined with ücoal accnrarv from 



the beginning course of th(> meltingpoinl-Iiiie. Fiom the \aliios, found 



for 7' (on pg. J6 of the dissertation) for ./■ z=: alom "/„ of meicni-v 



(pure tin), ./■ = (1,1005, ,/' = 0,171(5 and ,/■ =: 0,2o38, the average \alue, 



<]T 



obtained for , - is =z 200. From the deternn'nalions of IIkvcock and 



<l.r 



Xkvii,i,k between ./' = and ,/' =: 0.1 it also follow s. that =: 200. 



For we may therefore take (7'^ = 505): 



200 



— = 0.4 . 



505 — 



I calculated the values of «, ^ and y as follows: 



^(==0.325 ; ^?r=z — 1.11 : y = 1,.33. 



Formula (8) thus becomes: 



14-(0.325,6-^— l.lLr-'-fl.SS,/;'') 



Tz=zT ~ '■ -— - 



1— 0,4%(1— .^O 



and so we find the following values for T. 



The agreement is as good as can be expected : the difference between 

 the calculated value of T and the observed value genei-ally amounts 

 to fractions of a degree, average 0\8 ; as regards to the absolute 

 tem[)eratures the deviation is only average 0,2 7o- ^ïi^.Y llie two last 

 values are too low (the last 3 V»), ^'^1 tken the influence of a small 

 inaccuracy in the determination of the coefficients ^ and y makes 

 itself strongly felt. If we except these two last values, the calculated 

 meltingpoint-line fully coincides with the observed line in the scale 

 of the figure in the dissertation. And by means of a slight alter- 

 ation in the value of i? and y w^e might peiliaps cause the two last 

 observations to agree. Let us not forget, that the formula (8) 

 always remains an approximate one. In the last \alues of x the 

 compositioii of the sepai-ated tin nnist also make its influence felt. 

 For this is no longer pure tin but contains certaiidy 1"',,, or perhaps 

 even 6 "/„ of mercury. 



As regards the value of ^ (the heat of fusion of tin, when passing into 



the amalgam) — \vhen .v = 0, 7 = v„, that is to sav = = =: 



= 2550 gram-cals. At 25"^ our formida is no longer a\ailable, as 



