[Footnote: Read at an evening meeting of the Pharmaceutical Society of Great Britain, November 7, 1883.]

By Professor REDWOOD.

I have read with much, interest the paper on "Ointment Bases," communicated by Mr. Willmott to the Pharmaceutical Conference at its recent meeting, but the part of the subject which has more particularly attracted my attention is that which relates to prepared lard. Reference is made by Mr. Willmott to lard prepared in different ways, and it appears from the results of his experiments that when made according to the process of the British Pharmacopoeia it does not keep free from rancidity for so long a time as some of the samples do which have been otherwise prepared. The general tendency of the discussion, as far as related to this part of the subject, seems to have been also in the same direction; but neither in the paper nor in the discussion was the question of the best mode of preparing lard for use in pharmacy so specially referred to or fully discussed as I think it deserves to be.

When, in 1860, Mr. Hills, at a meeting of the Pharmaceutical Society, suggested a process for the preparation of lard, which consisted in removing from the "flare" all matter soluble in water, by first thoroughly washing it in a stream of cold water after breaking up the tissues and afterward melting and straining the fat at a moderate heat, this method of operating seemed to be generally approved. It was adopted by men largely engaged in "rendering" fatty substances for use in pharmacy and for other purposes for which the fat was required to be as free as possible from flavor and not unduly subject to become rancid. It became the process of the British Pharmacopoeia in 1868. In 1869 it formed the basis of a process, which was patented in Paris and this country by Hippolite Mege, for the production of a fat free from taste and odor, and suitable for dietetic use as a substitute for butter. Mege's process consists in passing the fat between revolving rollers, together with a stream of water, and then melting at "animal heat." This process has been used abroad in the production of the fatty substance called oleomargarine.

But while there have been advocates for this process, of whom I have been one, opinions have been now and then expressed to the effect that the washing of the flare before melting the fat was rather hurtful than beneficial. I have reason to believe that this opinion has been gaining ground among those who have carefully inquired into the properties of the products obtained by the various methods which have been suggested for obtaining animal fat in its greatest state of purity.

I have had occasion during the last two or three years to make many experiments on the rendering and purification of animal fat, and at the same time have been brought into communication with manufacturers of oleomargarine on the large scale; the result of which experience has been that I have lost faith in the efficacy of the Pharmacopeia process. I have found that in the method now generally adopted by manufacturers of oleomargarine, which is produced in immense quantities, the use of water, for washing the fat before melting it, is not only omitted but specially avoided. The parts of the process to which most importance is attached are: First, the selection of fresh and perfectly sweet natural fat, which is hung up and freely exposed to air and light. It thus becomes dried and freed from an odor which is present in the freshly slaughtered carcass. It is then carefully examined, and adhering portions of flesh or membrane as far as possible removed; after which it is cut up and passed through a machine in which it is mashed so as to completely break up the membraneous vesicles in which the fat is inclosed.

The magma thus produced is put into a deep jacketed pan heated by warm water, and the fat is melted at a temperature not exceeding 130°F.

If the flare has been very effectually mashed, the fat may be easily melted away from the membraneous matter at 120°F., or even below that, and no further continuance of the heat is required beyond what is necessary for effecting a separation of the melted fat from the membraneous or other suspended matter. Complete separation of all suspended matter is obviously important, and therefore nitration seems desirable, where practicable; which however is not on the large scale.

My experiments tend to indicate that the process just described is that best adapted for the preparation of lard for use in pharmacy. There is, however, a point connected with this or any other method of preparing lard which is deserving of more attention than it has, I believe, usually received, and that is, the source from which the flare has been derived. Everybody knows how greatly the quality of pork depends upon the manner in which the pig has been fed, and this applies to the fat as well as other parts of the animal. Some time ago I had some pork submitted to me for the expression of opinion upon it, which had a decided fishy flavor, both in taste and smell. This flavor was present in every part, fat and lean, and it is obvious that lard prepared from that fat would not be fit for use in pharmacy. The pig had been prescribed a fish diet. Barley meal would, no doubt, have produced a better variety of lard.