[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.
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