501 
tension curves, though the pressure measurement could take place 
“ here with greater accuracy. The values which were found for the 
vapour tensions (in cm. of mercury) with three different fillings, 
and which were used for the calculations of $ 17, have been combined 
in table 11 (p. 800). If in a graphical representation we draw log p as 
function of 7-1, one straight line can be drawn through the found 
points. A break is not to be found, though the pressure in the 
neighbourhood of the transition point has been determined with an 
accuracy of 1 or 2°/,,. As appears from table 11 the vapour tension 
line can be represented by the formula: 
. 1927.6 W. 
log p = — ——— + 6.8302. 
17. Determinations of the solubility of ammontun bromide in 
water for temperatures between 95° and 158°. 
The experiments were executed in the way described in § 5. The 
data are combined in table 12 (p. 802); 2 represents the number 
of molecules of NH,Br, present in one molecule of the mixture, 
and is therefore determined by : 
fF 
My, Br 9 
9 PO g + 948.7 
MNH,Br Mao 
In fig. 7 the values are drawn of /oga and 7. The values 
below the transition point appear to lie on a smooth curve with-a 
faint curvature; the curve is convex seen from below; through the 
points in the neighbourhood of the transition point, however, the 
straight line can be drawn given by the equation: 
372.7 
loge = — 7 + 0.31978. 
1 
The points above the transition Pee lie on the line: 
loy CaS > 
The concordance between the values calculated from these lines 
and the observations is satisfactory as appears from table 13. 
(Error 1°/,, or-smaller.) 
The two straight lines indicated above yield for the point of 
intersection : 
¢ == 1a7.4. 
51* 
