WHAT IS MILK?

New Zealand Mail, Issue 1156, 27 April 1894, Page 7

WHAT IS MILK?

It is strange how little is really known about milk, its chemical composition, and its physical contitution. More, indeed, is known about its sophistications than about the article which ia affecUd by them. Ten years ago our ideas had become fairly crystallised with regard to the fluid product of the farm, and it was then taught that the casein or curd existed in a state of solution in the watery part of the milk, and that the suspended fat globules, though of merely microscopic size, were each surrounded by an envtlope of some nitrogenous material, the rupture of which was an indispensable preliminary to the fusion of the fat globules into butter. Within the period named, however, the French dairy chemist, M. Duclaux, brought forwardstrong experimental evidence to disprove the existence around the fat globule of the thin envelope to which the name of Ascherson's membrane used to be applied. After much unlearning of what had previously been taught, tho doctrine of Duclaux at length gained the ascendency in this country. Tho membrane came to be regarded as mythical, and even its former supposed existence was rarely mentioned. At this stage of our " progress" we are startled by the recantation of Duclaux, who, according to recently published papers, now denies that the fat globules of milk are bare, and alleges that they are enveloped in a membrano of an albuminoid nature. Ho is also now of opinion that casein, as such, does not exist in milk, and ho looks upon milk as a humour rather than an emulsion. Ia these newest

ideas he finds himself in accord with his countryman Bechamp. It may be asked what possible interest such questions as these can possess for anybody besides theorists. The answer is, that when we can hit upon the exact truth regarding the composition and the constitution of the ingredients of milk, we shall occupy a better position than we do in regard to tho management of milk itself, the making of butter, and, in particular, the manufacture of cheese. Jn connection with the last-name' I operation especially there remains still far too much that is empirical. Our future practice will be very largely controlled by the correct answer, which, no doubt, will eventually bo given to the apparently simple question, What is milk 1 The greatest error we can commit at present, perhaps, is to think that we know all about it.—By Br William Freara, F.G.S., F.L.S,