THE NEW CHEMISTRY, A DEVELOPMENT OF THE OLD. 113 
loses something when it burns it must weigh less than before 
burning — as a fact it weighs more — therefore it has not lost 
but gained something. 
‘ Nay,’ replied the Phlogistean, ‘ it has lost something, but 
the weight of this something can only be expressed by a 
negative quantity.’ 
* But a something with such properties is an absurdity,’ 
replied the opponent, ‘ therefore it has no existence, and there- 
fore your theory is utterly false.’ 
The anti-Phlogistean triumphed, and the principle of levity 
was banished from chemical science. 
But the principle returned in a modified form. Lavoisier, 
who opposed the Beccherian theory of Phlogiston with signal 
success, himself propounded a theory of the constitution of 
solids, liquids, and gases, in which the ‘ subtle principle ’ 
‘ caloric ’ played an important part. Lavoisier regarded oxy- 
gen, as what he termed ‘ concrete oxygen ’ plus a something — 
caloric ; indeed he appears to have looked on all substances in 
the concrete state as solids, and to have supposed that the 
addition of a certain quantity of caloric to these caused them 
to become liquids, whilst the addition of a further quantity of 
caloric produced gases. 
Thus chemists seemed obliged to imagine a something in 
addition to the gross or ponderable matter of which bodies 
are composed, in order to account for the properties of these 
bodies. As science has advanced she has been able to define 
what this something is, at least, she has defined it more clearly 
than the older workers could do. 
I have said as science has advanced she has defined the 
unknown something; but it should be remembered that that 
wonderful book, which contains — according to the greatest autho- 
rities — the germs of all our modern advances, was written sixty 
years before Lavoisier’s time. Sixty years before the apparent 
overthrow of the theory of Phlogiston, Newton had laid the 
foundations of the science which was to reveal the true linea- 
ments of that Unknown whom the Phlogisteans ignorantly 
worshipped. 
We have learned to extend the meaning of the word thing — 
we speak of ‘ the power of doing work ’ as a measurable and 
definite thing — although not as matter : and we know that 
when a body burns it loses a certain amount of this power of 
doing work, or, as it is more shortly put, of energy. 
As usual it is a question of words. The older workers 
• could not define Phlogiston ; we are able to define energy, and 
therefore, we can see clearly where they saw but darkly. 
Chemistry now acknowledges that the properties of a com- 
pound are not only determined by the composition of the 
NEW SERIES, VOL. IV. NO. XIII. I 
