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Proceedings of the Royal Society 
tion is equally valid against the statement, that a clock, when wound 
up, contains potential energy, it is not the clock, but the clock and 
the earth, which contain this, and it is transformed when the clock 
weight and the earth approach each other. 
In fact, energy is not conceivable without a system of at least two 
bodies. 
We must, of course, recollect that the phlogistic chemists were 
ignorant of the existence and nature of oxygen, and it is to this 
ignorance that we must ascribe the downfall of the theory of phlo- 
giston. They attempted to explain, by means of this theory, facts 
(such as the increase of the weight of a combustible when burnt) 
depending on a totally different cause. They were thus led to 
modify the theory, and ascribe to phlogiston negative weight, and 
to identify it sometimes with carbon and sometimes with hydrogen 
gas. 
It is not surprising that the theory, thus mutilated, should have 
been overthrown, and we have only to regret that the valuable truth 
embodied in it should have been lost sight of ; that the antiphlo- 
gistic chemists, like other reformers, destroyed so much of what was 
good in the old system, and that, in consequence of this, we are only 
now beginning to see what was obvious to such a man as Stahl, that 
oxide of iron does not contain metallic iron ; that no compound con- 
tains the substances from which it is produced, but that it contains 
them minus something. We now know what this something is, and 
can give it the more appropriate name of potential energy; but 
there can be no doubt that this is what the chemists of the seven- 
teenth century meant when they spoke of phlogiston. 
The following Donations to the Library were announced: — 
Transactions of the Linnean Society, London. Vol. XXIV. Part 
3. 4to . — From the Society, 
Journal of the Linnean Society, London. Vol. VIII. No. 31 
(Botany). 8vo . — From the Society, 
List of the Linnean Society, London. 1864. 8vo . — From the 
Society, 
Proceedings of the Royal Society of London. Vol. XIII. No. 
69. 8vo . — From the Society. 
