527 
the difference between the molecular susceptibility of anhydrous 
ferric sulphate and that of ferrous sulphate I is only about 3°/,. 
We may note that A’ is the same for both anhydrous ferrous 
and ferric sulphates. 
For the behaviour of ferric sulphate at hydrogen temperatures we 
may refer to § 8. 
§ 5. Manganese chloride. Manganese chloride was used which 
had been freed from water as far as possible; it was not possible 
to make it quite anhydrous. As can be seen from the following 
table it obeys Curie's law exactly at temperatures above —208° C.; 
values are also given for hydrogen temperatures for which the law 
no longer holds. 
| TABLE IV. 
| Manganese chloride [, pulverised, no! quite anhydrous. | 
| T _|-106 z.T.109 Limits of H Bath 
290°.8 K 106.5 30970 6000--17000 G room atmosphere 
169 .6 183.4 | 31100 | 5000—17000 | liquid ethylene 
Td 403 | 31190 | 5000—16000 — 
| | | | | liquid 
|} 70.5 | 440 | 31020 | 7000-16000 | | 
| | | | nitrogen 
| 64 .9 | 480 31150 5000—16000 
20°: 1 1419 28520 5000—16000 
| liquid 
17 8 1589 28280 3000—10000 
| | hydrogen 
14 4 1881 27090 | 3000 —16000 | 
| | DE: 
The observations of KAMERLINGH ONNES 
§ 6. 
Gadolinium sulphate. 
| TABLE V. 
| Crystallised gadolinium sulphate I. 
| 7.108 | 
| 
| j Pal es Ih Limits of H Bath 
| ee aie | 
| _293°.1 K | 689 | 20190 9000-17000 room atmosphere 
20 1 997 5000—15000 
20049 | 
liquid hydrogen 
