1527 
3 3 
-a+—(u-+ u—! aaa et eee ie a te (Aled 
Git me w+ yu) + (1!) 
This is a straight line which cuts the axis for a= — (u + ut). 
If the difference of temperature wiich corresponds to this value 
is found by extrapolating from observations, the quantity e can thus 
be deduced. The expansion used in (10) and (41) would nearly 
always be sufficient in practice. This appears from the following 
values P of the expression in (9 
, computed rigorously with u = 1,1, 
which is close to the true value for many substances. In the next 
column the reciprocal value has been inserted; and in the fourth 
Extinction P (arbitrary unit). 
10 | 10S 
| | | | 
WE | En | P| form. (i1) | 
nT zi en 7 SS BIE —_ = 
0 18.58 | 0.54 1.88 
0.05 12.34 0.81 1.93 
OSD LOES OESO 1.98 | 
1 4,244 | 2.36 | 2.82 
2 Br Srl |e 3 A8 | 3.76 
a6 220 | 4.52 | 4.70 
7 | 1.186} 8.43 | 8.45 
‚10 0.885 | 11.30 | 11.26 
| 20 0.483 | 20.72 | 20.63 | 
column the same quantity, as it would be deduced from the straight 
line (asymptote of the curve). If necessary one could, of course, 
also use the rigorcus value for comparison with experimental data. 
Groningen, February 24, 1916. 
Chemistry. — “Glutaconic acid.’ (ID. By Dr. P. E. VeERKADE. 
(Communicated by Prof. J. BörsEKEN.) 
(Communicated in the meeting of February 28, 1916.) 
In the first communication') of this series I have shown that in 
all the known methods of preparing glutaconie acid (and these are 
very divergent) exactly the same acid is obtained ; hence this acid is 
distinguished from possible isomerides by an extraordinary stability. 
1) These Proc. 18. 981 (1915). 
