eight atoms of oxygen must have been furnished to convert the four equivalents of carbon of every atom of acetic acid into carbonic acid. But these changes which acetic acid undergoes will be made more apparent from the subjoined diagram:

CONVERSION OF ACETIC ACID INTO CARBONIC ACID AND WATER.

It becomes a matter of great interest, then, though unfortunately one of great difficulty also, to ascertain whence this large amount of oxygen is supplied. Any opinion, however, on this point, must, in the present state of our knowledge, be purely conjectural; yet, at the risk of appearing presumptuous, I shall hazard a few speculations on the subject, which, though they may not carry conviction, will, I hope, excite inquiry, elicit discussion, and perhaps conduct to knowledge; for, to use the beautiful language of Bulwer, it should ever be remembered that the agitation of thought is the beginning of truth.

There are, I think, only three sources whence the oxygen can be furnished-from the food, the atmosphere, or the organism, including, by this last term, all the products, normal and abnormal, which exist for the time being in the system. As, for obvious reasons, there was no great likelihood of the oxygen having been derived from the food of those patients whose cases have formed the basis of these observations, I pass at once to the consideration of the second and third named sources. It is the opinion of Liebig, that the salts of the vegetable acids, which are converted in the system into carbonates, derive the supply of oxygen necessary for that purpose during respiration. This, however, is given, if I mistake not, merely as an opinion-certainly not supported by demonstrative evidence, and, if I recollect rightly, not even by a reason why these salts should appropriate oxygen in their passage through the lungs; and, with all deference to so great a master in science, while no proof is afforded in favour of the opinion, there are one or two circumstances which, I think, are entitled to consideration as militating against it. In the first place, the speculation assumes that the decomposition and reconstruction of these salts are effected in the lungs, and leaves out of view the more likely influence of digestion in effecting such changes. Again, this opinion presupposes a greater activity of the respiratory process while such salts are making the transit of the lungs-an event not appreciable, certainly, by any increase in the number of the respirations. And, if more oxygen be not withdrawn from the air, and it be maintained, notwithstanding, that the supply of the gas necessary for converting acetates, &c., into carbonates, is furnished during respiration, then the advocates of that opinion are shut up to the conclusion that, in order to effect the alteration of certain salts, some part or parts of

the organism are deprived of a portion, or, for anything we know to the contrary, of all their oxygen-a procedure scarcely in accordance with the general tendency of nature's operations. A theory at least as plausible, I conceive, as this, and one as much in unison with ascertained facts, can be constructed, by supposing that the necessary oxygen is derived from the organism itself. That the effete portion of the organism is being continually disintegrated and resolved into a variety of new forms in the capillary laboratory of the system, is well known and undeniable; is it too much, therefore, to suppose that, amid these ever-varying transitions, a vegetable acid may be broken up and altered, by being brought within the sphere of nascent oxygen, evolved from compounds yielding to the resistless influence of the secondary destructive assimilation? This, however, is all theory-and, probably, very erroneous and untenable theory —and, therefore, though agreeing with Dr Whewell, that "false theory often proves more advantageous to science than the absence of theory," I shall descend from the airy region of speculation, and leave to others the task of solving this interesting problem in the chemistry of therapeutics.

I have thus submitted evidence, that the acetate of potash is a valuable agent in certain cutaneous diseases; I have also proved that it increases the water of the urine, and its solid constituents likewise; have shown that it is itself converted into a salt, which dissolves and transforms tissues which are but imperfectly organised; and lastly, I have endeavoured to show, that the beneficial effects of the medicine are in some way, yet unknown, connected with the change which is effected in itself. Whatever opinion may be entertained of the theoretical conjectures I have hazarded, I trust my readers will not overlook the practical observations which have been presented likewise; and, in the hope that these will be submitted to the test of experience, I respectfully urge them on their consideration.

ARTICLE IV.-Case of Spontaneous Expulsion of the Child; with Remarks on this Form of Delivery, and on the Treatment of the Placenta under extensive Morbid Adhesions. By ROBERT DYCE, M.D., Lecturer on Midwifery, Marischal College and University, Aberdeen.

(Read at the Medico-Chirurgical Society of Aberdeen.) I was called about midnight on Saturday, 30th December 1848, by a midwife, to visit Mrs C, the wife of a tradesman, living in Castle Street. I was informed that labour had commenced in the evening about six hours before,-that the presentation remained long high, that the membranes ruptured naturally,-that the waters were in great quantity, and that several strong pains had followed after the discharge of the waters, before any part of the child could be felt, a limb was at length reached, which was made out by her

NEW SERIES.-NO. V. MAY 1850.

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to be an arm. When I first saw the patient she had very strong forcing pains, the arm was at the top of the vagina, doubled up, so as to present the elbow. A part of the child, nearly equal in bulk, was felt on either side of the presenting limb,-viz. one part near the pubes, and the other near the sacrum, but so high that, unless I had passed my whole hand into the vagina, which I did not at the time deem essential, the individual parts could not be made out. It was sufficient for my purpose that the arm presented, and that delivery could not be accomplished without turning the child. In order, therefore, to render the operation easier, by quieting the uterine action, which was very powerful, I gave her, as soon as it could be procured, a tea spoonful of laudanum, determining to operate the moment a lull took place. This, however, never happened, for presently the pains forced the elbow lower, the hand came down into the vagina with hardly any assistance, and was ascertained now to be the right one. At this time the proportionate size or bulk of the two parts of the child became remarkably altered. The arm, shoulder, and neck, which formed one part, pressed towards the pubes, and appeared smaller; while the other end of the tumour, which was now distinctly made out to be the back of the child, along with the ribs and spine, which was twisted and bent, now came completely to occupy the hollow of the sacrum. It now became very apparent that nature was to complete the delivery herself, by expelling the child double, or by what is called spontaneous expulsion. At length, after two or three powerful pains, the shoulder was very closely pressed, or jammed rather, against the arch of the pubes, and at length external to the vulva, while the breech pressed out the perinæum, and was expelled by a very long and powerfully-continued pain, the feet following quickly in its wake, the arm never moving from its position under the pubes. The head soon followed, and the delivery was speedily completed. The child (a girl) gasped once or twice, but could not be recovered.

The size of the abdomen indicated the presence of another child, which, on examination per raginam, was confirmed, as the membranes were reached. I also discovered in the examination a circumstance by no means desirable,-viz. that the integuments of the abdomen, limbs, face, and in short the whole body, were extensively oedematous, for lying, as the patient did, with her back towards me, I had no opportunity of discovering this before.

No pain coming on in half-an-hour, the membranes were ruptured. The waters were in very great quantity. An arm again presented, but along with the head. It was attempted to keep up the limb, so as to let the head descend alone; but the pains were so violent, that both head and arm were forced into the pelvis, and expelled together. The breech remained during two or three equally severe pains at the birth, owing to the cord, which was very short, being twisted round one thigh and leg, by which it was tucked up tight upon the infant's abdomen; its removal immediately caused the