WHY DOES THE BUTTER COME?

Globe, Volume XXIV, Issue 2668, 25 October 1882, Page 3

WHY DOES THE BUTTER COME?

It is known that the fat in tho milk is is the form of minute ipbcrioal globules, z-ud that these being ligkt*r than the enrrtnr.ding liquid, or tbe milk serum, as it it nanveniently called, collect mostly at tbe surface when the milk ia allowed to stand qaiotiy for a time, and that when either cream or the milk is violently agitated to as to throw those globules against o.*e Another, they Btiok together in larger and l&rgsr numbers until finally visible olumpe of better appear. All this we knew full wi>;i| but wise men of Bcianoe and of prac;iec have sought for many years for an explanation of thesa familiar phenomena, without hring able as yet to find one that is in all r.-spcote •o satisfactory as to meet with universal aocoitanoe, ,

I The oldest theory of any importance, a: 'I J one that is familiar to many, is that eacb I little globule of fat is enclosed in an er,vtlops- ! or be o of albuminous matter, and that es !o?V ; bo theae sacs are vholo the globulus of f r.% niil not stick together any mare th*n will two pats of butter r.iosly wrapped up in cloth, or two sausages iu their ikios j but these sscs are supposed to be very thin and tender, and to be weakened by acid*, and tSut wfcen they are knocked together, especially in the acid oream, their envelopes soon get worn through or torn, and tho fat escapes and naturally collsots together, while tho remains of the delicate saca in the buttermilk make it turbid. This explanation is generally attributed to a F/enohman, who announced it in 1812 ; it looks plausible, for it appears to explain many of the phenomena satisfactorily • but the one most serious difficulty with it is that so many eminent microtcspi&a have searohod for these sacs or parts of tric-n without being able to identify them. When we find all who havo the necessary experience to enable them to understand oorreetiy what they see with it, uniting in the declarative that according to the best of their knowledge the fat globules are not encased in membranous sacs, we can safely affirm thai the* theory lacks its most essential foundation stone, and that the question, why &'jch t.hc butter come, mutt be answered in tome other way.

A second theory is that the fat globules, though entirely bare, are nevertheless at closely surrounded in the milk, and < specially in the cream, with a cart cf thickened milk serum, that they are kept apart until. by being thrown forcibly together in thechurn or in any other way, the slimy layer u momentarily squeezed out from, between them, and they adhere. Soxhlct, to whom we owe many valuable contribution* to our knowledge of milk, explaini why the butter comes, that has many strong points in ite favor, Butter fat melts at about SOieg. Fahrenheit j but he takes the petition, to begin with ; that even in cold ores.cn the fat is still in liquid form, as it was iu tt« warm milk just from the udder—that each «,lobu!e is a globule of a liquid, and no* of a solid, asmight naturally be expected at low temperatures. That a substance may retain its liquid form at a temperature much below that at which it remains solid when once solidified, is a well-known physical law, and he illustrates it for this particular case by interesting examples which I oan but very briefly notioe. Water, if allowed to stand iu perfect quiet in a oold room may fall to several Negroes below its natural fretsing point without freesing | but as soon as the glass containing this under-cooled liquid is moved so as to agitate its contents, psrbape ever so little, fieeaing follows mstattly. Many of our readers may have themselvesobserved this phenomenon. When tho liquid is divided into very fine particles it is sdli easier to carry it to very low temperatures without freezing j and this subdivision may be pushed so far that the smallest globules will require violent shaking up as well as ft . low temperature for their solidification. Again, it is a well known physical phenomenon that when a liquid is thus divided up- . into very small globules, wbichare suspended in the midst of another liquid with whiei ' they do not mix,, in the same manner £3 oil . will remain entirely unmixed with water, these globules do not run together as they . would naturally be supposed to do; on the contrary, they resist at>y attempt to make them unite, and are more likely to subdivide still further if pleased together. It is quits possible, then, for the globule* . of fat in the milk to retain their liquid form,, even when the milk is very cold ; and in remaining apart, they only do what any liquid globules would do under the same circumstances. Now when this mass of liquid fatglobules ia the cream, cooled down below the temperature at whioh the fat of which they are composed is solid, is shaken up in the churn, tbe same results should follow as when the tumbler of underoooled water is shaken j the globules solidify suddenly, and then they adhere when thrown against each other ; this is Soxhlet's answer to the question Why does the butter oome t If this is the correct answer, then freezing tbe milk so thoroughly that even the fat solidifies should ct least i» part take the place of churning, since the first labor of the churning is spent m getting the globules into the solid form so that they ■ will adhere. Such a result was obtained la. one experiment by Soxhlet. A quantity of milk was divided into two equs' part;, one which was ktpt at about 68deg Fahrenheit, while the other half was oamplcteiy frcaen, and then thawed out by putting the vessel in water at 68 deg; both portions cf milk were then churned as nearly as passible in., the same manner in small glass churns, end that one which had boon frczon was brought in two minutes to the conditicn in which the butter was just ready to come, while the, other portion required eleven minutes to rsacb. the same condition.

But even this theory, which appears to be' so fully in accordance with fchs laws that' govern the behavior of liquids, end which does not seem to assume anything opposed to' the facts, and was consequently v ry widely approved, is not allowed to have undisputed possession of the field. Stcrclr, an eminent Danish investigator of milt, docs cot find that the question put at the head of this' article is satisfactorily answered. His answer, however, as well as perhaps an attempt to answer that other question which sometimes presents itself to the practical dairyman—Why doesn't the butter come t—must be deferred for consideration until another time.