386 
already a considerable vapour-tension at such high temperatures. 
The evaporated salt sublimes against the colder parts of the suspen- 
sionwire in tbe form of very small crystals, or as a thin coherent 
layer; the increase of weight, corresponding with it, makes the 
upwards-driving force also seem smaller than it really is. It is 
rather difficult to determine afterwards the correction necessary by 
it, or even to estimate its magnitude with any certainty. 
Although the thus obtained results cannot be considered so accurate 
as possibly we should wish, we think it, however, wholly justified 
to consider them as giving a very satisfactory idea of the true 
specifie gravity of this liquids, and to give a sufficiently accurate 
result for the dependence of the specifie gravity on the temperature 
in the case of these molten salts. 
The weight of the platinum conus with the submerged part of 
the wire was at 25° C. 12,1772 grams (corr); the specifie weight 
of the platinum at 25° C. was pycnometrically determined at 21,47; 
and at O° C. at 21,485. At # C. it was calculated from the 
expression : 
et 21,485 
* 1+ 3(0,000008868 ¢ + 0,000000001324 2) 
Let P be the weight of the sinker with wire in air, p its weight 
if submerged in the liquid, then ?—p is the upwards driving force, 
as it seems to be. The real force A however is greater, and equal 
to: P—-p + 0,0001 x, . ; 
From this it follows: 
A specifie weight of the liquid — specifie weight of air 
gaat specitic weight of the platinum 
> 
from which thus the specific weight of the liquid at ¢ C. follows 
torue- > 
+ 0,001. 
For all salts the specific gravities were calculated in this way. 
§ 3. In the following pages we have shortly reviewed the data 
thus obtained in the case of a series of salts and other inorganic 
compounds. Of every salt we have reproduced the figures for three 
temperatures at least, and we have, moreover, mentioned the general 
empirical formula, from which the density at other temperatures 
were intraor extrapolated. We have added the values of the molecular 
free surface-energies of the liquids at the same temperatures, in 
Erg per ¢.m*, and some remarks on the magnitude of its temperature- 
