The acids which have been described as existing in opium are meconic, sulphuric, lactic, and acetic acids. It is not certain that the two latter are always present. In any case they exist in small amount, and are of little importance. For many years after its discovery in 1805 by Sertüurner, meconic acid was regarded not only as the peculiar acid of opium, but as that with which the morphine and some of the other bases are wholly combined. In later years it has become known that the morphine exists partly as sulphate, but I do not find that any analyses have been made, showing to what extent this is the case. The subject has indeed received but little attention, as is evident from the fact that in many of the most recent publications it is assumed that the morphine exists naturally entirely as meconate.