An alkali—for instance, NaHO—gives with acetic acid a salt, C2H3NaO2, which on decomposition retains carbonic anhydride, forming a carbonate, Na2CO3, and marsh gas is given off:
C2H3NaO2 + NaHO = Na2CO3 + CH4
Marsh gas is difficult to liquefy; it is almost insoluble in water, and is without taste or smell. The most important point in connection with its chemical reactions is that it does not combine directly with anything, whilst the other hydrocarbons which contain less hydrogen than expressed by the formula CnH2n + 2 are capable of combining with hydrogen, chlorine, certain acids, &c.
If the law of substitution gives a very simple explanation of the formation of hydrogen peroxide as a compound containing two aqueous residues (OH)(OH), then on the basis of this law all hydrocarbons ought to be derived from methane, CH 4 , as being the simplest hydrocarbon. The increase in complexity of a