9 SO 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[Jane 3,187L 
tlic fallen weight is lifted up, provided with energy, and 
enabled to fall again ; that the potential chemical energy 
of metallic lead did not originate in the lead, hut is 
energy or phlogiston transferred thereto from the char¬ 
coal by which it was smelted; and, lastly, that the che¬ 
mical energy of the charcoal itself, its capability of 
burning, its power of doing work,—in one word, its 
phlogiston is merely a portion of energy appropriated 
directly from the solar rays F 
If this be a correct interpretation of the phlogistic 
doctrine, it is evident that the Stahlians, though igno¬ 
rant of much that has since become known, were never¬ 
theless cognizant of much that became afterwards for¬ 
gotten. For most of what has since become known, 
mankind are indebted to the surpassing genius of La¬ 
voisier ; but the truth which he established, alike with 
that which ho subverted, is now recognizable as a partial 
truth only; and the merit of his generalization is now 
perceived to consist in its addition to—its demerit to 
consist in its supersession of—the not less grand gene¬ 
ralization established by his scarcely remembered prede¬ 
cessors. This being so, the relationship to one another 
of the Stahlian and Lavoisierian theories of combustion 
furnishes an apt illustration of the general truth set 
forth by a great modern writer, that “in the human 
mind one-sidedness has always been the rule, and many- 
sidedness the exception. Hence, even in revolutions of 
opinion, one part of. the truth usually sets while another 
rises. Even progress, which ought to superadd, for the 
most part only substitutes one partial and incomplete 
truth for another; improvement consisting chiefly in 
this, that the new fragment of truth is more wanted, 
more adapted to the needs of the time, than that which 
it displaces.” 
The partial truth contributed by Lavoisier was indeed 
more wanted, more adapted to the needs of the time, 
than the partial truth which it displaced. To him che¬ 
mists are indebted for their present conception of mate¬ 
rial elements ; and especially for their knowledge of the 
part played by the air in the phenomena of combustion, 
whereby oxygenated compounds are produced. The phlo- 
gistians, indeed, were not unaware of the necessity of 
air to combustion, but, being ignorant of the nature of 
air, were necessarily ignorant of the function which it 
fulfilled. To burn and to throw off phlogiston being 
with them synonymous expressions, the air was con¬ 
ceived to act by somehow or other enabling the combus¬ 
tible to throw its phlogiston oft’; and a current of air 
was conceived to promote combustion by enabling the 
combustible to throw its phlogiston off more easily. 
Moreover, contact of air was not essential to combustion, 
provided there was present instead some substance, such 
as nitre, which equally with, or even more effectively 
than air, could enable the combustible to discharge itseif 
of phlogiston. But while the phlogistians, on the one 
hand, were unaware that the burnt product differed from 
the original combustible otherwise than as ice differs from 
water, by loss of energy; Lavoisier, on the other hand, 
disregarded the notion of energy, and showed that the 
burnt product included not only the stuff of the combus¬ 
tible, but also the stuff of the oxygen it had absorbed in 
the burning. But, as well observed by Dr. Crum- 
Brown, we now know “that no compound contains the 
substances from which it was 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 seventeenth cen¬ 
tury meant when they spoke of phlogiston.” 
Accordingly, the phlogistic and antiphlogistic views 
are in reality complementary, and not, as suggested by 
their names and usually maintained, antagonistic to one 
another. It has been said, for example, that, according 
to Stahl, the product of combustion is simple, and the 
combustible a compound of the product with imaginary 
phlogiston, which is false; whereas, according to La¬ 
voisier, the combustible is simple, and the product a 
compound of the combustible with actual oxygen, which 
is true. But in this case, as in so many others, every¬ 
thing turns upon the use of the same word in a different 
sense at different periods of time. When Lavoisier 
spoke of red lead as being metallic lead combined with 
oxygen, ho meant that the matter or stuff of the red load 
consisted of the matter or stuff' of lead plus the matter or 
stuff of oxygen. But when the Stahlians spoke of me¬ 
tallic lead being burnt load combined with phlogiston, 
they had the same sort of idea of combination in this 
instance as others have expressed by saying that the- 
weight of a body is compounded of its matter and its 
gravity; or that steam is a compound of water and 
heat; or, to use a yet more Lavoisierian expression, that 
oxygen gas itself is a compound of the basis of oxygen 
with caloric. It is not, then, that the one statement, 
Stahlian or Lavoisierian, is false and the other true, but 
that both of them are distorted, because incomplete. 
Chemists nowadays are both Stahlian and Lavoisierian 
in their notions; or have regard both to energy and 
matter. But Lavoisierian ideas still interfere very little 
with our use of the Stahlian language. While we ac¬ 
knowledge that in the act of burning the combustible and 
the oxygen take equal part, just as in the act of falling- 
the weight and the earth take equal part, yet in our 
common language we alike disregard the abundant 
atmosphere and abundant earth as being necessarily 
understood, and speak only of the energy of the com¬ 
bustible and of the weight, which burn and fall respec¬ 
tively. Whatever may be the fault of language, how¬ 
ever, chemists do not omit to superpose the Lavoisierian 
on the Stahlian notion. They recognize fully that it is- 
by the union of the combustible with oxygen that phlo¬ 
giston is dissipated in the form of heat; and further, 
that phlogiston can only be restored to the burnt com¬ 
bustible on condition of separating the combustible from 
the oxygen with which it has united; just as energy of 
position can only be restored to a fallen weight on con¬ 
dition of separating it to a distance from the surface on. 
which it lias fallen. 
That Stahl and his followers regarded phlogiston as a 
material substance, if they did so regard it, should inter¬ 
fere no more with our recognition of the merit due to* 
their doctrine, than the circumstance of Black and La¬ 
voisier regarding caloric as a material substance, if they 
did so regard it, should interfere with our recognition of 
the merit due to the doctrine of latent heat. But though 
defining phlogiston as the principle or matter of fire, it 
is not at all clear that the phlogistians considered this- 
matter of fire as constituting a real body or ponderable 
substance ; but rather that they thought and spoke of it 
as many philosophers nowadays think and speak of the 
electric fluid and luminiferous ether. The nondescript 
character, properly ascribable to phlogiston, is indicated 
by the following quotation taken from Macquer’s ‘Ele¬ 
ment de Chymie Theorique,’ 1749. It must not, of 
course, be forgotten that the popular impression as te 
phlogiston having been conceived by its advocates as a. 
material substance having a negative weight or levity, is 
erroneous; and is based on an innovation that was intro¬ 
duced during the struggling decadence of the phlogistic 
theory, and advocated more particularly by Lavoisier’s 
subsequent colleague, Guyton de Morveau, in his ‘ Dis¬ 
sertation sur le Phlogistique, considere comme Corps 
grave, et par rapport aux changemens de pesanteur qu’il 
produit dans les corps auxquels il est uni,’ 1762. Mac- 
quer writes as follows :—■ 
“ La matiere du soleil, ou de la lumiere, le phlogis¬ 
tique, le feu, le soufre principe, la matiere inflammable, 
sont tous les norns par lcsquels on a coutumo de designer 
1’clement du Feu. Mais il paroit qu’on n’a pas fait une 
distinction assez exacte . . . . du nom qu’il merite. ven- 
tablement lorsqu’il entre effectivement comme principe- 
dans la composition d’un corps, ou bicn lorsqu’il est seul 
et dans son etat naturel. Si on 1’envisage sous ccttc 
