3f2 THE ANALYST. CORRESPO NDErVCE. [The Editors are not responsible for the opinions of their Correspondente.1 CANE STTGAR I N MILK. To THE EDITOR OF ‘( THE ANALYST.” SIR,-In the current number of THE ANALYST Mi-. J. H. Collins has given an interesting account of a case of adulteration of milk with cane sugar. I ask him, in the interests of all public analysts, to publish f u l l details of his methods of analysis, for I confess that I am puzzled by Mr.Collins’ figures, and do not see how he has made out that the milk he speaks of was adulterated with 20 per cent. of a solution of cans sugar having the same specific gravity as ordimtry milk. A solution of cane sugar of the specific gravity of ordinary milk (Le., 1.030) contains 7-44 per cent. sugar (7.65 grammes i n 100 c.c.).If a milk containing 3.2 per cent. fat, 9.3 per cent. eolids not fat, and 12.5 per cent. total solids, were mixed with a solution of cane sugar of specific gravity 1.030, in the proportion of 80 gallons of milk to 20 gallons of the sugar solution, we should get the following fignres, which I compare with Mr. Collins’ milk. Fat ... . . . . . . . . . 2-40 . . . . . .3-00 Solids not fa;“ . . . . . . . . . 9.03 . . . . . . 9.37 Total solids . . . . . . . . . . . . 11-43 . . . . . . 12.37 Sugared milk. Mr. Collins’ milk. Mr. Collins’ figures lead to the following composition of the original milk, on the assumption that 80 gallons of milk were mixed with 20 gallons solution of cane sugar :- Fat . . . . . . . . . . . . . . . . . . . . . . . . 3-75 Solids not fat .. . . . . . . . . . . . . . . . . . . . 7.84 Total solids . . . . . . . . . . . . . . . . . . . . . 11.59 It appears l o me that the sophistication of milk with a Eolution of cane sugar presents considerable difficulties : the use of a solution of the density of inilk would materially diminish the amount of total solids in the milk; whilst the use of a solution of sugar contehing the same percentage of solids as milk would materially raise the specific gravity of this fluid.I t is difficult to reconcile Mr. Collins’ analysis with his conclusions. I also demur entirely to his stitement that the whey of a milk sophisticated with syrup may be easily tested for cane sugar by dividing a measured quantity into two parts, inverting the sugar in oue half by sulphuric acid, and titrating both with Fehling’s solution.Fehling has stated (Ann. Pharm. 104, 79) that it is impossible to estimate milk sugar accurntely by his solution without first converting the lactin into dextrose, and the widely discrepant statements published respecting the quantity of copper that a molecule of milk sugar reduces bear out this statement. Doubtless Mr.Collins bas better evidence to advance than that already published of the pophistication of the milk in question, but he will serve the interests of public analysts by publishing that evidence. Yours, &c , Guy’s Hospital, January Stla, 1879. THOS. STEVENSON. ALUM IN FLOUR. TO THE EDITOR OF “THE ANALYST.” SIB,--SO much has been written about the detection of alum in flour, by the logwood test, that I feel somewhat reluctant to add to the bulk of matter.When I tried the value of the test for niy own edifica- tion, I carried out some experiments, which at the time, I thought scarce worth rccording. As the results throw some additional light upon the risk of failure in the use of the logwood test for alum in flour, and the reason of such failure is not exactly rendered apparent, I will ask space to make the following observations.One would have thought that since the publication of the note, “On the Detection of AIum in Flour,” by blr. Carter Bell, in the Analyst,* (which seems to be ignored by recent observers) no more would be heard of the fallacious character of the logwood test, Under the impression that the baking of the bread rendered the alumina insoluble, and that this was necessary to ensure the success of the test, I took some flour purposely alumnised, and moistened it with baryta water, and, on adding an ammoniacal solution of logwood, obtained no indication of alum.I afterwarda tried lime water, a solution of chloride of barium, and chloride of calcium with similar results but on mixing the alumnised flour with water (by mistake), and then adding baryta water, the logwood solution alone, or the ammoniacal solution produced the blue colour.I subsequently found that the addition of the chemical compounds enumerated did not interfere with the production of the blue colour, which was produced when the flour wasmoistened with water. The results obtained, were, however, not always the same, and I noticed that the stronger the alcoholic Eolution of logwood wag, the more risk of failure, and when absoluta alcohol mas employed, eren if the flour h i 1 been mixed into a stiff phste with water, no * Yol.2, p, 28.THE ANALYST. 33 blue colour appeared, I found that this was due to the insolubility of alum in alcohol, hence the failure of the experiment.I then tried an aqueous solution of logwood, and noticed that it was infinitely preferable to the alcoholic solution for detecting alum in $our, and it has never failed to indicate the presence of alum throughout my experience. I take a small quantity of flour and rub it up well in a glass mortar with a dilute aqueous solution of logwood, to which a few drops of carbonate of ammonia solution have been added.The solution of logwood should only be slightly darker in colour than a saturated solution of bichromate of potash, and it should be added in sufficient quantity to convert the flour into a very thin paste. I am, &c,, CARDIFF, January 151h9 1879. J. R‘. THOMAS. To THE EDITOR OF “THE ANALYST.” SIR,-The interest still felt respecting the question of alum in flour has, I observe, again, brought the subject to the surface; and I take the opportunity of bringing to the notice of your readers a mattm which may have some influence on the views of some persons, who look on the subject in a somewhat exaggerated way.Twenty-five or twentp-six years ago the practice of adding alum to flour by the corn millers waw very common, at least I may say it was so in this district.Several prosecutions were instituted in which I was professionally concerned. Under an old Act of Parliament search, under a Magistrate’s Warrant., cau be made by a constable, and this authority was exercised in some of the cases I allude to. It wm then discovered that those who practised this art, had special machinery for doing it, namely, a kind of r r d l axed in the top part of the building, which ground the alum at a certain rate, and distributed it by means of spouts or conductors into the hopper or other receptacle of the wheat, and was ground with it by the stones.This method, I apprehend, is still pursued whenever the adulteration is practised by the miller. The idea that the alum could be distributed with sufficient regularity by the hand of a workman in a large mill is untenable. Another erroneous notion that appears to haye taken posseasion of 60me minds, is that small doses of 3 or 4 grains of alum to a pound of flour would be of any use, or that it would be worth anybody’s trouble putting such small quantities in. appears in print there is a deal to unlearn on this subject. Judging from what now and then F. M. RIMMINGTON. BRADFORD, Janrtary 14th, 1879.