The French who advocated Substitution Theory had no clue of what determined the archetypal structure of their Types. Here is what Dumas wrote in 1840 (Ann. chim. Phys.,  73, 205):
[Molecules are like] planetary systems held together by a force resembling gravitation, but acting in accord with much more complicated laws.
Not everyone agreed with the French. Here is the advice of Liebig to his Ph.D. student Kekulé, who was about to leave Giessen, population ~9,000 in 1850s, for further studies in Paris, where Dumas held court:
There you will broaden your horizons, there you will learn a new language, there you will learn to know the life of a great city, but there you will not learn chemistry!
The doctrinaire views of the French and German establishments in the 1840s are reminiscent of the following quote from A. N. Whitehead:
Clear-sighted men of the sort who are so clearly wrong now proclaimed that the secrets of the universe were finally disclosed. If only you ignored everything which refused to come into line, your powers of explanation were unlimited.
Chancellor's Address, Bonn 1877
(quoted in K. Haffner, Angew. Chem., Eng. Ed., 18, 644 (1979)
At that time [~1850] a general feeling of
discouragement had just overcome the most influential chemists.
Because whole categories of facts could be reconciled neither with
one another nor with the general theoretical views of the time, it
was believed that all
speculations had to be banned from chemistry and all atomistic
British chemist Alexander William
(1851, he was 27 years old)
(quoted in C. A. Russell, History of Valency, p. 51)
Formulae--may be used as an
image of what we rationally suppose to be the
arrangement of constituent atoms in a compound, as a
is an image of what we conclude to be the arrangement of our