„28 
and Perrier were supplemented by those included in table V (p. 327) 
which further confirm the validity of Curin’s law and the absence 
of saturation phenomena. 
This result, on account of the large number of magnetons present 
in gadolinium sulphate and «f the resulting large value of the a of 
LANGEVIN at this low temperature is of importance to LANGEVIN's 
theory, according to which saturation phenomena are here still outside 
the limits of experimental accuracy. 
§ 7. Summary of the deviations from Curin’s law. We here append 
the representation of the experiments of KAMERLINGH ONNEs and PERRIER 
on dysprosium oxide (Comm. N°. 1227) by the formula y (7’+ 4’)= C’. 
TABLE VI. 
. Dysprosium oxide 
represented by the formula 
an nn 
T | 7.10° AT+4").10° | 
288°.5 K 229.2 69790 
170 374.6 69670 
[132 .79 445.7 66320] 
20 7.25 1915 69420 
17 .94 2032 68970 
15 .95 2173 69430 
13 .93 2334 69860 
With the exception of the measurement made with liquid ethylene 
boiling under reduced pressure, which is rendered doubtful by the 
otherwise good agreement between observation and formula, the 
differences do not exceed the limits of experimental error. 
If we collect the various data hitherto given in this paper the 
following different cases are seen to occur. 
Gadolinium sulphate follows Curtm’s law over the whole region of 
low temperatures down to the lowest hydrogen temperature, 14° K, 
throughout the whole of this region we may call it a normal para- 
magnetic substance. 
Over the whole region of low temperatures and down to the lowest 
hydrogen temperature dysprosium oxide obeys the law (T° + A!) = C" 
