Se OTES ON SCIENTIFIC RESEARCH. o Mi / sh 
> : PMubierschicy in a ® treatise “On the relations of ‘temperature and pressure of 
% ~ saturated vapours”, gives a new formula for the relation ‘between pressure and tem- 
_ perature of saturated steam. After mentioning the equations formulated by Clapeyron, 
- Zeuner, Clausius and Callendar, in which in addition to pressure and temperature other 
properties of steam are taken into consideration, the author discusses Biot’s, Schle- 
miiller’s and Bertrand’s interpolative equations and afterwards van’t Hoff’s and van der 
Waals’ equations of condition. The equation constructed by Kubierschky according to 
_ the steam pressures compiled in Landolt-Bérnstein’s book, 4th edition, runs as follows: — 
Io pe az Deb t48 (t— 100) 
Set 250.00 
It is, indeed, very simple, but shares with many others the disadvantage of depending 
somewhat upon temperature. Thus the value 230.39 is to be calculated at 
232 for 0: 50: 300° 
229 , 0:200: 300° 
-233 ,, 0:100:374° 
_ Not quite so exact, but sufficient for practical purposes, are the following abbreviated : 
equations: — a 
: i Ig p (in atmospheres). .-. = 2 
: 5.1 (t — 100) 
lg P (in 1/1000 atmospheres) = peo 7 
Seo (t —— 991) 
RB a0. 
ee ods (E== 100) 
i fae 2518) 
ade 8 (t+ 19) 
{ fp Ga. min: -Ho) <2 Sa pa) | | 
q The pressures of saturated steam, calculated according to these abbreviated formulas, 
_ deviate by 1 to 1.18 per cent. within the temperatures of from 15 to 30°C. Otherwise, 
the deviations from — 16 to 300° C. are less then 1 per cent., on an average only 
about 4/2 per cent. iss 
The result awakens a certain theoretical interest, as in spite of numerous 5 tem 
there was not, so far, such a simple interpolative formula for the calculation of the 
pressure of saturated steam at a temperature given. In its dependence upon temperature, 
it resembles the other known p,T-equations, which fact strengthens the supposition 
that liquid water too, as the various kinds of ice, possesses a different molecular 
constitution according to temperature. 
The author believes that his abbreviated formula is suitable for cneieednes but, 
in our opinion, it would be more advantageous to use tables instead of calculating 
the desired pressure in each case. 
ony, 
> 
- 
3 
a 
= 
lg p (in kilos/sg. cm.) . 
: Ig p (in mm. Hg) + 2.881 or 
| 
he Nae i elite beheld 
W. P. Jorissen and J. A. Vollgraff’s treatise”) on the electric conductivity during the 
___ oxidation process of benzaldehyde and pinene, discussed on page 63 of our previous 
: Report, has now been published elsewhere*). So far, except in flames, a distinct dis- 
persion of the electric charge during the oxidation process had only been noticed in 
the case of eeeeEE es (phosphorus trioxide), whereas all attempts to prove that the 
at 
1) Zeitschr. f. angew. Chem. 29 (1916), I. 305, — 2) Chem. Weekblad 12 (1915), 93. — 3%) Zeitschr. f. phystk. 
_ Chem. B® (1915), 553. 
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