242 NOTICES OF THE MEETINGS [Jan. 28, 
by the action of the chloride of benzoil C, H, O Cl on the benzoate 
of potash. It is a crystalline body, perfectly neutral to test paper, 
scarcely soluble in water, readily soluble in alcohol and ether. 
On continued boiling with water, it is converted into hydrated 
benzoic acid, one atom of the anhydride with one atom of water 
forming two atoms of the hydrated acid by an interchange of 
hydrogen and benzoil. Besides several of these anhydrous acids, 
Gerhardt has prepared some intermediate acids, analogous to the 
intermediate ethers, by combining two different radicals in the 
same group. Thus chloride of benzoil with cuminate of potash 
Cro oe O formed cuminate of benzoil or benzocuminic acid 
Gry AO aehves : ? 
A aye O O; and in like manner, several other intermediate acids 
1 5 
were prepared. 
In conclusion, to this very brief exposition of this important 
series of discoveries, the Lecturer alluded to a feature of the 
development of the human mind in scientific research, which is 
strikingly illustrated by the substance and form of these results, 
and of which instances are probably to be found in the history of 
many others. The explanation of the above reactions consists in 
a combination of two modes of reasoning, which were developed 
by different schools, and for many years were used independently 
of one another. Gerhardt, to whose researches and writings some 
important steps in the doctrine of types are owing, formerly 
believed the truths which he saw from that point of view to be 
incompatible with the idea of radicals, but he now joins those 
chemists who find in each of these notions a necessary and most 
natural complement to the other. 
May we not hope that such may be the result in other cases of 
difference of opinion on scientific questions, which the progress of 
knowledge will shew to have been owing to the incompleteness 
and one-sidedness of each view, rather than to any thing absolutely 
erroneous in either ? 
[A. W. W.] 
