Chemistry Reference
In-Depth Information
14.2 Prerequisites for Chemical Activities
14.2.1 Operations, Relations, and Relata
A chemical body is defined by means of the attributes that it can display in a precise
context and also by means of the operations involved to individuate it. Let us just
illustrate this with Peirce
s definition of lithium:
If you look into a textbook of chemistry for a definition of
lithium
,youmaybetoldthatitis
that element whose atomic weight is 7 very nearly. But if the author has a more logical mind
he will tell you that if you search among minerals that are vitreous, translucent, gray or white,
very hard, brittle, and insoluble, for one which imparts a crimson tinge to an unluminous
flame, this mineral being triturated with lime or witherite rats-bane, and then fused, can be
partly dissolved in muriatic acid; and if this solution be evaporated, and the residue be
extracted with sulphuric acid, and duly purified, it can be converted by ordinary methods
into a chloride, which being obtained in the solid state, fused, and electrolyzed with half a
dozen powerful cells, will yield a globule of a pinkish silvery metal that will float on gasolene;
[then] the material of
that
is a specimen of lithium. (Perice, 1931-1958, CP 2.330)
1
'
Peirce confidently endorses the idea that lithium can be defined as a set of
instructions aimed at permitting not only the identification but also the production
of a specimen of lithium. This definition is clearly provisional and open-ended so
that the word
'
lithium
'
will acquire new meanings as we learn more about the thing
or stuff to which it refers. For Peirce reality appears to us under the form of a
continuum within which there are no absolute individuals (Peirce, CP 6.170).
The
indeterminacy
of operationally defined individuals such as specimens of
lithium should be related, according to Peirce, to
a principle of contextuality
:
Any discourse about an object cannot exhaust the potentially infinite, determina-
tions of that object. Peirce remarked:
The peculiarity of this definition is that it tells
you what the word
lithium
denotes by prescribing what you are to
do
in order to gain
a perceptive acquaintance with the object of the word
'
(Peirce, CP 2.330).
Operations and instruments were essential parts of the definition of substances
in eighteenth-century chemistry. The French chemist and apothecary, Guillaume
Fran¸ois Rouelle, asserted that
[c]hemistry is a physical art which, by means of certain operations and instruments, teaches
us to separate the various substances which enter into the composition of bodies, and to
recombine these again, either to reproduce the former bodies, or to form new ones from
them. (Eklund
1975
,p.2)
'
s description of reactions in his “Table des rapports” the relational
character of the phenomena is clearly presented.
One applies mercury to a silver dissolution in nitrous acid; this substance having more
relation with this acid, than this acid has with silver, it unites to it and precipitates silver.
If one decants the liquor one will have separated silver, and on the other side mercury
dissolution in nitrous acid, if one adds a lead blade to this mercury dissolution, lead has
In Venel
'
1
Peirce
s use of italics.
'
