2 THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALSSTS. MEETING, November, 1883. Mr. WIWER, President, in the Chair. AT the dose of the reading of papers on Milk," the members and visitors present joined in a discussion, of which the following is an abstract :- THE PRESIDENT, in opening the discussion, trusted that no personal matters mould be introduced into it. He indicated the main points i*aised by the papers of Messrs. Estcourt, Dupr6, Hehner and Allen, and asked those following to keep as close to the matters thus brought €orward as possible. He called upon Ur. Voelcker, as. a visitor interested in the subject, to open the discussion. DR. VOELCKER made some preliminary remarks directed to dispel the idea that he was an abettor of adulteration and an enemy to public analysts generally.Hq had not thought it worth while to meet these insinuations before, because he felt convinced that the ideas of all as regards the composition of milk would undergo before long im- portant modification. The question really arose was milk a fluid of such constant com- position as Mr. Wanklyn had originally asserted it to be and did not the feeding of cows upon brewers' grains or immature produce of a succulent nature produce a considerable increase in the per-centage of water ? Taking up first the question of ash, which as a rule might rise as high as '8, but the general average of which mas *75, yet he had found 1.15, both in the morning and the evening milk of the cow, I n this result he had since been corroborated by Dr. Hoffman, who had found an ash of 1.17 in the mixed milk of a herd of Jersey cows.To show the possible variations in the ash he found in the same chemist's report on agricultural chemistry, such numbers as 1.17, 091, -92, and -72. Referring now to the solids %not fat he contended that although not so uncertain as the amount of fat, yet they still varied to a considerable extent in genuine milk. His analyses made in 1863 (with no other object than that of securing good milk for the Professor:'s table at Cirencester) strongly supported this view. He believed with most public analysts that the per-centage of solids not fat in milk approached as a rule very much nearer 9 than 8, but he was at the sawe time bound to assert that you might have most excellent milk and yet having the proportion of solids not fat sunk down to 8.8 or 8.7.Last October he had a fresh case in point where he examined the milk of the cow which had just taken the prize given by the Farmers' Association, both for quality and quantity. The milk gave 14.25 total solids and 5-54 fat, thus leaving 8-71 solids not fat. In sup- port of his general views on this point, he again referred to the latest annual report just issued by the eminent authority on agricultural and dairy chemistry already men- tioned. In this there is the account of experiments on the milk of a herd of 104 CONS, whichwere not specially fed. From January 1st till May 25th, the total solids were 11.8 in morning, and 11.1 in evening milk, while from May 25th to October 29th, they were 12 in morning milk, and from October 29th to December 31st they were 12 in morning and * See ANALYST, for December, 1883.THE ANALYST.3 12.14 in evening. the cows gave as an average :- Taking the whole year, so as not to weary the meeting by details, Morning Evening Total solids . . . . 11-93 . . . . . . 11*97 Fat . . . . . . 3.24 . . . . . . 3.25 Solids not fttt . . . . 8-69 . . . . . . 8.72 while on no single occasion during the whole year did the solids not fat amount to 9. Alluding next to the process of analysis he considered that any mere drying for so many hours was not reliable, but that it was better to actually dry the milk till the weight was const&, irrespective of t h e , and he considered that many of the small discrepancies between analysts had occurred through occasional imperfections in drying.Turning to the subject of the analysis of sour milk be expressed a strong opinion that no analyst was entitled to come to any definite decision as the original compo8ition of decomposed milk. Coming, in eonclusion, to the really practical question of what should be the standard for the judging the quality of milk, he suggested that the limit of the future should simply be that all milk sold must contain II; rnhzinzum of t h ~ p e r cmt. of fat. In his opinion this was all that was required to insure to the consumer an article of fair quality, and at the same time it would not press unduly on the milk producer, and he trusted that public analysts as a body would take this suggestion into serious consider- ation. DR. MUTER reminded the meeting that they were there sot so much to dispute over the past as to concert what was to be done in future.Yaking first the method of analysis, it shouldbe carefully reconsidered un the basis of (1) Drying tBhe residue to a constant weight, and (2) Extracting the fat either by Soxhlet’s method, Bell’s method, or by evaporating upon plaster of Paris, powdering and extracting with ether, which latter was his customary manner of working before the establishment of the Society of Public Analysts. He did not at tho moment express any opinion as to which was best, but they should all be tried, and themost accurate and scientific method should be chosen for future universal use by all public analysts. Coming to the matter of the standard he considered that the whole difficulty had arisen by the slavish method of judging milk by the solids not fat alone.Ete had never pe:mitted himself to be bound by such an idea and had more than once pointed the danger out; in the course of dis- cussions. Eis experience was that whenever he got solids not fat appreciably below 9, then his fat was proportionately high. For want of a better term he had mentally classed such milk as being naturally diluted with- fat. His suggestion for the change in the standard of milk vould be this :- (1) To adhere to the limit of 9 per cent. solids not fat, provided the fat did not exceed 3 per cent., but if the latter were over 3 then he would take the limit of 8.5. So far he had always gone with Mr. Bell. when the milk was excessively rich in fat, but he diverged entirely from him in themethod of calculating the probable dilution, He held that, given a departure from the above limits, the dilution should always be calculated on 9 solids not fat as representing fair average milk and not on the abnormally low limit of 8.5.Referring to theanalysis of decomd posed milk, he considered, and had proved many times, that any attempt to lay down a true allowance was impossible. Many years ago he had tried his hand at such allow-4 THE ANALYST. ance and had then come to one which sometimes held pod, and which was similar to that afterwards worked out by Mr. Bell, but subsequent experience had shown the absolute futility of such attempts. I n some few cases he had found avery close agree- ment between himself on the fresh milk and Mr.B d on the stale; but again only last week a case occurre& where the analyst on the fresh milk, using the 8.5 standard, found ~ o t less than 5 per cent. watep, while Xr. Bell, using his allowance and the same standard, found not less than 14 per cent. I t was to be remembered that the legisla- ture, in compelling the Somerset House chemists to give an opinion on what they them- selves must admit to be very uncertain grounds, had placed them in a most invidious position, and he questioned whether some amendment of the Act wasnot necessary to enable them to state (as the public analyst would be entitled to do) that the article they received was not really in a fit state for analysis, and thus to decline to give an opinion in doubtful cases.MR. HEISCH, after some preliminary remarks on the methods of analysis, commented unfarourably upon Dr. Voelcker’s suggested standard. The relative values of fat and of non-fatty solids depended entirely upon what the milk was intended to be used for. In the case of young children, for example, the solids not fat mere of much higher importance than the fat ; and in fixing a standard this important consideration should not be lost sight of. When milk was put into coffee, the fat was the important factor ; but when actually taken as nourishment then the solids not fat were the desirable constituents. In addition, the judging of adulteration on fat would be a matter of decimal fractions only-that was always undesirable. He strongly urged, in conclusion, that no allowance for decomposition could ever be fairly applied to any sample of stale milk, a8 no such thing as a constant factor could be obtained. Mn.AXGELL, after pointing out the undesirability of taking fat a8 a Btandard, and giving the reasons for his opinion, took up the consideration of the effect of feeding on milk. He agreed with Dr. Voelcker that by special feeding the quantity of fat in milk might be materially increased ; but hQ entirely questioned the influence of feeding in the other direction. MR. DYEB, referring to certain analyses of his which were brought forward in the Manchester case, said that it was true they Rhowed averages of 8-77’ and 8.74 solids not fat ; but then, on the other hand, there was respectively 3.33 and 3-51 of fat, an amount far exceeding the SocietF’s limit’; and this mas a point which had been entirely lost sight of.DR. BOSTOUK HILL strongly supported the present standard. During the last 18 months he had analysed 360 samples, all mixed milk of dairies of over 10 cows, and the averltgs was--soZids saotjkt 9.3, and fat 32. They should be very careful in consenting to lower the limit, because he was firmly of opinion that genuine healthy milk never gave less than 9 per cent, non-fatty solids. After supporting his contention by several experimental facts, he turned to the question of the analysis of aour milk, which he showed vas perfectly unreliable, and that no analysis, however corroctecl by allowancerJ 9 could ever be satiafactory ; and he detailed experiments he had made in support of this contention.THE ANALYST.5 - - - --- MR. BAYNES supported the Society’s limit, and denied that the British milk standard mas to be judged by the continental cows. He knew from practical experience that a quantity of Dutch milk was proposed to be sold in this country, and samples were submitted to him for his opinion. He found that in only one case did the solids, not fat, reach 9, while the €at very seldom came up to 3. Re had cerfified that he would not allow such milk to come into his district. MR. 8. HARVEY, in the course o€ his remarks, also in €avow of sustaining the present h i t , stated incidentally that he never met with a really genuine milk under 9 solids not fat. 3% would for every reason totally decline to ever certify upon the fat alone, as the difference between purity and adulteration would be far too narrow in figures to be safe.Ma. JOHNSTONE made some personal remarks upon the processes of milk analysis, calling attention ider ctlicr; to the fact that some analyses of his, based upon a system of prolonged drying, had been received doubtfully at first by those who now appeared to be coming round to his way of thinking. MR. HEIINER also followed with similar remarks, in which he commented upon observations by Mr. Johnstone and Dr. Nuter. MR. ALLEN, in the course of his reply, said he considered they had reason to com- plain of the form of the Somerset House certificates, which did not state the probable amount of water which had been added to the original milk. He also thought it wrong that they did not state all the data upon which they based the opinion given.With regard to the fat in milk, he was inclined to consider that its average amount was much higher than some analysts seemed to think, being more like 3.5 than any lower number. Dn. DUPRE, in replying on the discussion, remarked that it was an unfortunate fact that although the public benefited by the Act, it never assisted the public analysts, The only proper solution of the difficulty would be to cause all milk sold at a certain price to have a corresponding strength. As to the figures he had brought forward in his paper, although based upon four very carefully couducted analyses, he did not considor them final, and they were possibly destined to be modified to some extent. THE PRESIDENT, in summing up the discussion, made some remarks showing the entire unrelinbility of tho analysis of stale milk. He was then elaborating an extensive series of experiments on the subject which he hoped soon to make public. I t was unanimously resolved that a committee be appointed to consider the whole queatiou. AN ORDINARY GENERAL MEETING of the Society was held at Burlington House on Papers were read by Wednesday, December 19th, 1583, the President, Mi. Wiper, in the chair, Mr. ICingzott 011 ‘* Rape Oil, Beef Fat, and Mutton Dripping ; ’’ and by Mi*. Hehncr on “Honey.” Theso papers will be published in our February number. CONCLUSION OP THE ~OUIETY’S PROCEEDIXGS.