learning." While with Herr Duehring "elevated notions of exact knowledge in mechanics, physics and chemistry" are, as we have seen, the foundations. But that the public may be in a position to decide we shall examine somewhat more closely the example cited by Marx in his note.
Here we have, for example, the homologous series of compounds of carbon of which many are known and each has its own algebraic formula. If we, for example, according to the practice of chemistry, represent an atom of carbon by C, an atom of hydrogen by H, an atom of oxygen by O and the number of atoms contained in each combination of carbon by n, we can express the molecular formula of each one of this series thus,
CnH2n + 2 — Series of normal paraffin.
CnH2n + 2O — Series of primary alcohol.
CnH2nO2 — Series of the monobasic oleic acids.
Let us take, for example, the last of this series and set one after the other n = 1, n = 2, etc., we get the following results omitting the compounds.
CH2O2 — Formic Acid boiling point 100° — melting point 1°.
C2H4O2 — Acetic Acid — boiling point 118° melting point 17°.
C3H6O2 — Propionic Acid — boiling point 140° — melting point —.
C4H8O2 — Butyric Acid — boiling point 162° — melting point —.
C5H10O2 — Valerianic Acid — boiling point 175° — melting point —.
And so on to C30H60O2, Melissic Acid, which melts first at 180°, and which has no boiling point, because it does not evaporate without splitting up.
Here we see therefore a whole series of qualitatively
