116 !EiX ANALPIST. NOTES ON 8OME OLD PROOES8ES OF MILE ANALYSIS AND ON A RA!i!IONBL VIEW OF MILL( STANDAJ3DS. BY JOHN MUTER, PILD., F.I.O., 6tc. W ~ L E we are all awaiting mxioudy the report of the Milk Committee of om Society on the best method for milk analysis and the standards for the same, it may not be out of place (in the present dearth of €reah matter in the food analysis line) to put before the members some old reminiscences and a few additional arguments in ftzvour of the 'I sliding scale '' standard, advocatod by several analysts, who sham my views on this point. In my whole experience of milk (extending to a period conaiderably prior even to the pm&g of the old Adulteration Act, of 1872), I. have in my books no record of any unimpeachably pure milk in which the m m of the Ron-fatty constituents fell markedly below the present ordinarily accepted limit, d g s s whgre the fat was considerably above the amount u ~ u d y expected, and in this matter my experience is fihmed by several andyste who have had the opportunity of examining large quantities of genuine milk. Before the formation of the Society of Public Analysts, and the &cial adoption by it of Mi!- Wdyn'a then recently publishedmpid pivcess (but not of his standard, which was reduced €ram 9-3 to 91, those few persons who were training themelves to specia1 experience in food, and a&ng as pioneers of the large body of andfiioal OheInists now devoted to its examination, used to make first a preliminary test of the milk by taking tihe speoif~o gravity of %he ndk and of its 8wum after coagulation, and then afterwards mnhn the results by a full analyaia.This analysis was conducted always by one of two processes, and although I aftem& gave them up in deference to the Bociety, and adopted Wdyn's procesq and the 9 standard, I have 'never been at d sure that it vm an improvement in red acouracy. As it is possible that aome of our younger mem- bers may not know what wa15 done before the passing of the Acts, tho foUoming account may be interesting :-By the first process, a funnel, furnished with four high but narrow ribs, was Wed with a filter paper, and then filled, two-thirds of its height, with sand (which had been purified by washing in dilute hydrochloric acid and igniting), This wa8 then placed in the air-drying oven at 220" Fdw.€or some time, cooled €or ten minutes in a dessicator, and weighed. Enough milk was dropped q o n it aa as to nemly saturate fhe sand turithozct wotti4tg tltapqm, and the whole again weighed and thon dried in the oven until pracdidy conatant, always using the ~ame dessicator fozTHE ANALYEiT. 217 a similar timo at each weighing. Tho funnel and its contents were then thoroughly pemlated with boiling ether, by placing it in a tin jacket into which warm water was put, and then pouring on the othor, and finally it was removed from the jsoket and again dried in the oven, and the loss was fat. The residue was then treated with water, faintly acidulated, or with vory woak spirit, to removo tho soluble portion, which was looked upon QS omdomilk sugar, and then again dried, an4 the balance was looked upon as orudo casein.The ash was takon on a separate sample. By the seconif process a portion of the milk was evapomted in a flat dish, and tihe residue taken when driod at 220Q Fah. to pmotid conahmy, and then this residuo was also used for ash determination. Another portion was evaporated with ph~ter of Pmis, being well stirred during the evaporation, and the iiryrosidue havingbeenreduced topomilorinaglaasmortar, was extracted absolutely with boiling ether. Tho ether was received through a filter into a weighed flat-bottomcd flask, and having beeu distilled off, the reaidual fat mas dried at 220° I?. and weighed. The plaster remainder in tho baain and filter were now fxeatetl with water, and the bdmce between the fat and augar and the tots1 was casein.I am not now putting forward the amounts of so-oalled milk sugar and casein as specimens of first-rate aepma- Gion, but I still hold, and havo always done so, that either of these processes are better in regard to the fat sepmation than W d l y d s , although, of come, not so rapid. When we used these processes, the ddation from solids not fat was unknown, and we judged by a general consideration of d the figures obtained. There ia no doubt the discoverg of &. Waiiklyn, re solib not fat, was a distinct advance, but in my opinion the great error whi& has all dong boen made, consists in a too blind adherence to &at standard, and a too rigorous judging of milk upon non-fatty aolids done, without &o tahg into consideintion tho mount o€ fat.There can, undoubtedly, o m , bothin nature and ’by bad mnpling, cases of what 1 have before ~ a J l ~ d (‘ natnra[l dilution with fat,” and the non-fatty solids do not then show what they ought fa do. To make this plain, let me take from my books by C~WOQ an old case, where a sample of milk, very nearly at the Society’s limit, had been standing in a dish, and the sample had been dipped out by a sweep of tho measure, which did not go nearly to the bottom. I?&* e . b e .. .. 4.61 Non-fdty solids I . w . ., 8*80 - -- - -- TOM I. a b a . 13-81 and yet? on pfoperly mixing that veq same milk, we get :- Bat .. .. . I .. 3‘49 Non-fatty rJolidrJ . . .. .. 9-02 - Total ,, D , .* 12.61 - On the other hand, lot UFJ glance at the effect of akhmhg.Taking tihe of a good COW, usod for my ova f a d y ? 1 found:- Fat b e - 6 6 . .. 4% Eon-fatty ROE& a b . .. 9-66 Total b . O D I n l4*27 -- -118 THE ANALYS!I!. NOW placing the milk in separators, and exaslining the bottom layer, we have (I), after about an hour- Fat I* .. a . .. 3.08 Non-fatty diih . . .. 9.79 - Total .. . a .. 12.87 (2) After about two hours- Fat .. .. .. .. 1-43 Non-fsftysolids .. .. .. 10-04 Total .. .. .. 11.47 (3) After four houm- Fat I. .. .. I . *36 N~a-bWrrOlids .. .. ,. 10.65 TOM .. .. .. 10-90 - Thug, it ia evident that, taking the low standards adopted by Mr. Bell, o€ 2.5 fat and 8.5 noa-fatty solids, without any modification on the sliding male principle, a milk- man, by taking away one-hdlf of his cream nearly, might then add almost; fifteen por cent. of water, and laugh at the inspector.It is a simple fact that, at least in the Metro- polis, the knowing ones of the trade systematically skim down to about 2.5, and thus, not only sell the cream, but are enabled to add, without fear, an average ten per cent. of water. I do not here make any suggestion as to the exact mannor inwhiehasliding s d e of solids not fat, based UPOR the fat found, should be applied, as that is a matter for the mmmittee, &odd such an idea find favour in their eyes, but I do put it atrongly as a 8hp1e matter of common seme, that there should not be the same standard for whole milk and for even partially skimmed milk. Given first an agreement to some fixed process which obtains a raidue dried to fair constanoy, and then regularly geta out the whole of the fat (ae both the old proceases I have referred to undoubtedly do) then whatever limit may be adopted for non-fatty solids should only hold good provided the amount of fat be ndt undH 8 certain amount, and if it be so then I hold that for every half per mnt.of fat under the limit an addition ahould be made to the standard of wEda not fat nntil sbsohtely skimmed milk was reached, of which, by-the-bye, I have never met with an undoubtedly unwatered specimen under 9.8, Any new standard which may be proposed by our committee would bo in the present state of the law practidy useless unless approved of by Mr. Bell and his colleagues, and I, therefore, trust that (as both their and our only object is coming amem the truth as possible) they will see fit to give ~ome consideration and experiment towards the approval or otherwise What is really wanted, both on behalf of the dealers and the public, is an mend- ment of the law similar to that shown in the New Zealand Food Act (recently printed in the AXALYST), wherein a schedule of standards is given, such sobedde to be subject of the “&ding scale” system.THE ANALY8!I!. 119 to periodicd additions and revisions by order in Uounci.l OR the recommendation of a specid Boaxd of Experts, and d porsons interested in the purity of food should d t e in akivlng to attain this consummation 130 devoutIy to be wished.