Note 27 — Chapter VIII · CARBON AND THE HYDROCARBONS

This is always true for hydrocarbons, but for derivatives of the lower homologues the law is sometimes different; for instance, in the series of saturated alcohols, CnH2n+1(OH), when n = 0, we obtain water, H(OH), which boils at 100°, and whose specific gravity at 15° = 0·9992; when n = 1, wood spirit CH3(OH), which boils at 66°, and at 15° has a specific gravity = 0·7964; when n = 2, ordinary alcohol, C2H5(OH), boiling at 78°, specific gravity at 15° = 0·7936, and with further increase of CH2 the specific gravity increases. For the glycols CnH2n(OH)2 the phenomenon of a similar kind is still more striking; at first the temperature of the boiling point and the density increase, and then for higher (more complex) members of the series diminish. The reason for this phenomenon, it is evident, must be sought for in the influence and properties of water, and that strong affinity which, acting between hydrogen and oxygen, determines many of the exceptional properties of water (Chapter I.).