The study of the organic acids appears scarcely to have advanced of late years pari passu with the other branches of organic chemistry. It seems, indeed, as if the development of each of the different departments of the science had been, to a certain extent, periodical; each engrossing the labours of investigators to the temporary exclusion of the others, themselves to be renewed when some new experiments should reawaken an interest in them.

However this may be, the subject of the natural and artificial bases has proved so productive of interesting results as to have recently become the chosen and almost exclusive field of inquiry, notwithstanding several investigations which have thrown much light on one class of organic acids, namely, that represented by the general formula Cn Hn O4. With the exception of this section, the history of the organic acids remains very imperfect, and in many cases we have but a meagre account of a few of their salts.