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the central claims of his chemical philosophy.
15
Additionally, van Helmont
s
importance in the context of chemical ontology goes further inasmuch as he takes
one of the first steps towards the naturalization of chemical explanations, by
employing the notion of a physical particle as the object of change. Although his
explanations are not entirely physicalistic and naturalistic, van Helmont signifi-
cantly contributes to the naturalization of chemical ontology and of chemical
philosophy and, thus, towards its modernization.
Before we examine the fully mechanistic seventeenth century Epicurean
atomism, it is important to discuss the work of Daniel Sennert (1572-1637), who
serves as a significant transitional figure between the work of van Helmont and that
of the mechanistic atomist, Pierre Gassendi. As early as 1619, Sennert embraces a
theory that mediates between a strictly Aristotelian and a strictly Democritean
conception of matter. Sennert believes, like Democritus, that all things are made
of atoms but he also believes that atoms are endowed with substantial forms.
Thus, although Sennert adopts an atomic theory of matter, he believes that atoms
are not simply mechanical in nature but associates them with “formative forces in a
sense similar to the
archei
of Paracelsus”
16
and of van Helmont. One of the aspects
of Sennert
'
s work that influences the later development of chemistry, however, is
his operational notion of substances as “the limits attained by the analytical
methods of the laboratory.”
17
Sennert appropriates this
'
negative-empirical con-
'
, as Bensaude-Vincent and Stengers have called it,
18
cept
from the tradition of
'
Scholastic alchemy.
This negative-empirical concept acquires particular explanatory significance in
the context of one of Sennert
s most influential experimental procedures, the
reduction to the pristine state. For this experiment, Sennert employs nitric acid to
separate silver from an alloy of silver and gold,
19
and he describes the results of this
procedure as follows: “If gold and silver melt together, they are so roughly mixed
per minima that the gold cannot in any way be detected by sight, but if aqua fortis
is then poured on, the silver is so thoroughly dissolved that no metal can be detected
in the water by sight. But since it is really present, it can emerge thence in
segregated form, and certainly in such a way that both the gold and the silver retain
their own nature.”
20
'
The empirical basis of [Sennert
'
s] atomistic assertion is easily grasped. First, and most
important, the silver has been so thoroughly combined with the gold and then dissolved by
nitric acid that it is no longer perceptible. And yet, despite having been subjected to one of
the most powerful agents of analysis available in the seventeenth century, the metal can be
regained intact by means of precipitation. From the perspective of the
'
negative empirical
'
principle, it is therefore operationally
a
-
tomos
- indivisible - since it has resisted all efforts
at laboratory decomposition into its components. Second, the precipitated silver particles
15
Debus (
1977
), p. 327.
16
Ibid
, p. 192.
17
Newman (
2006
), p. 97.
18
Bensaude-Vincent and Stengers (
1996
), p. 37.
19
Newman, p. 99.
20
Sennert (
1619
), p. 32.
