��OUTLINES OF PHYSICAL CHEMISTRY
��the other divalent metals, than for the monovalent. The reason of this most be traced to the acid sulphates, which are more or less readily formed according to the nature of the base. But it will be sufficient to have called attention to this point. The following are some acids to which Ostwald has applied his method, along with the results he obtained:
�� �Avidity
� �Avidity
�HNO $
�CH 1 OH.C0 2 H .
�HC1 .
�CH^COj^H
�CCVCOjH .
�Butyric acid .
�CHC1 2 .C0 2 H
�Isobutyric acid
�CB^CLCOsH
�■
� ��These examples might be multiplied, and it might be shown that certain other physical properties, particularly may be used to reveal the nature of the equilibrium in more or less complex solutions. These, however, will not be gone into, but just before closing this chapter I should like to say a word or two about a very interesting reaction in which the substances exert an influence by constant active masses. The work of Deville (1871) on the action of steam on metallic iron and of hydrogen on f erroso-f erric oxide is well known. These two actions which take place at a high temperature are reversible :
8Fe + 4H 2 Z Fe 3 4 + 4H 2 .
The stationary equilibrium does not in any way depend on the relative quantities of iron and of the magnetic oxide, but only on the presence of these substances and on the proportion of hydrogen mixed with the water- vapour. This proportion may be so much the smaller as
��1 More particularly the refractive power and the power of absorb- ing light. By a study of the rotation Jellet has been able to deter- mine the distribution or division of hydrochloric acid between two alkaloids in alcoholic solution : the alkaloids studied were quinine, codeine, and brucine.
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