NOTES OF THE MONTH. The Lewisham Board of Works has been reckoning up the cost of the Adulteration Act, and it finds that since 1873 its expenses have been £718; or, in other words, the enormous sum of £100 per annum spent to secure a pure food supply in the district. Naturally an immense outlay like this startled the board, and they thought it most unsatisfactory, especially because during all the seven years they had only caught 67 offenders, and they forthwith proceeded to propose the cutting down of the salary of their unfortunate analyst, because, apparently he could not make good things bad. We do not know whether the board ever dines at the expense of the rates, but if it does so, then £100 a year would be nothing for that purpose, of course, although £100 a year for the protection of the ratepayers is of course dreadful, and ought to be at once put down! Had the board stopped here it would not have been much matter, but they proceeded to decide to trouble the other vestries with their nonsense, and spend money in sending copies of this report to all the Metropolitan Boards, asking them each to count up their costs, and have a conference on the subject, so spending more money, although with what object is not clear. Surely no money is better spent than that expended by the sanitary committees of the various vestries, and even if it ends in comparatively few "cases being obtained, that should be a matter of congratulation, because it shows the food purveyors of the parish to be honest men, desirous of selling an honest article, and that the nuisances and other sources of disease are reduced to a minimum. Money is spent by the vestriesnot to obtain the greatest number of convictions-but to act as a deterrent against fraud, and if that end be obtained, the happiest parish is that in which the fewest "cases can be got, always supposing, of course, that the inspectors of nuisances really do their duty. A most important decision has been recorded in the High Court of Justice, which our readers will find fully printed elsewhere. We hope that the attention of inspectors, and sanitary committees, under whose direction they act, will be given to this case, because one great difficulty is that the inspector may be watched, and the milk watered while he is safe in another part of the parish. If, however, some temporary deputies be employed, taking care to change them each time, no adulterator could ever say he was safe, even for an hour, and milk businesses would not be found to be so lucrative an investment as they are at present, according to the Provisioner, which states that some have been lately fetching the enormous sum of £8,000. We have heard of one district in which an intelligent woman, nicely got up with a neat market basket to hold the bottles, and a jug on her finger, did wonders in one day with the inspector following her, taking the filled bottles and giving her three empty ones after each transaction. Here is an advertiser hoist on his own petard in an amusing manner : Sausages that will keep sweet for some days during the hottest weather can be made with the aid of 's Food Preserver, at a cost of not less than a halfpenny a pound." As will be seen from the reprint on another page, the State of Wisconsin has passed an Act to prevent adulteration, and it is very pleasing to find that it follows so closely the lines laid down by the English Act. BOOKS, &c., RECEIVED. Water Analysis, by Dr. Frankland; Supplement to a Handbook of Chemical Manipulation, by C. Greville Williams; Manual for the Physiological Laboratory, by Harris and Power; The Chemist and Druggist; The Brewers' Guardian; The British Medical Journal; The Medical Press; The Pharmaceutical Journal; The Sanitary Record; The Miller; Journal of Applied Science; The Boston Journal of Chemistry; The Provisioner; The Practitioner; New Remedies; Proceedings of the American Chemical Society; Le Practicien; The Inventors' Record; New York Public Health; The Scientific American; Society of Arts Journal. Owing to the pressure on our space this month, we are obliged to omit several articles already in type, including one by Mr. Carter Bell, "On the Manufacture of Citric Acid." THE ANALYST. JULY, 1880. 123 SOCIETY OF PUBLIC ANALYSTS. A GENERAL MEETING of this Society was held at Burlington House, on Wednesday, 2nd June, the President, Dr. Muter, F.C.S., in the chair. The Scrutineers having examined the voting papers reported that Mr. J. J. Eastick, Analyst to Fieldgate Sugar Refinery, had been elected as a Member. The following gentlemen were proposed for election as Members :— S. A. Goldschmidt, Ph.D., F.C.S., Analyst, of New York. J. Blake White, M.D., Analyst to Health Department, New York. The following papers were then read and discussed: "On Means for Increasing the Certainty of Perception of Colour Change in Various Titrations," by Dr. Dupré. "On the Determination of Organic Carbon in a Water Residue," by F. P. Perkins. "Note on the Analysis of some Samples of Chian Turpentine," and "On the Relation of the Scale of Baume's Hydrometer for Liquids Heavier than Water to the Specific Gravity," by G. W. Wigner. "On Phosphoric Acid in Potable Waters," by O. Hehner. NOTE ON A SIMPLE MEANS FOR INCREASING CERTAINTY OF PERCEPTION OF COLOUR CHANGE IN VARIOUS TITRATIONS. By A. DUPRÉ, Ph.D., F.R.S. Read before the Society of Public Analysts, on 2nd June, 1880. As is well known, the change from pale yellow to red, in the titration of chlorides by means of nitrate silver with neutral chromate as indicator, is more distinctly perceived by gaslight than by daylight. No doubt eyes differ in regard to their power of perceiving slight variation of colour tint, and in my case I have always found it advisable, in the analysis of potable waters, containing from one to two grains of chlorine per gallon, considerably to concentrate by evaporation previous to titration, or else to perform the tritation by gaslight. The adoption of the following simple plan enables us, however, to perceive the change of colour as sharply and with as great a certainty by daylight as by gaslight. The water is placed into a white porcelain dish (100 c.c. are a useful quantity), a moderate amount of neutral chromate is added (sufficient to impart a marked yellow colour to the water), but instead of looking at the water directly a flat glass cell containing some of the neutral chromate solution is interposed between the eye and the dish. The effect of this is to neutralize the yellow tint of the water, or, in other words, if the concentration of the solution in the cell is even moderately fairly adjusted to the depth of tint imparted to the water, the appearance of the latter, looked at through the cell, is the same as if the dish were filled with pure water. If now the standard silver solution is run in, still looking through the cell, the first faint appearance of a red colouration becomes strikingly manifest, and what is more, when once the correct point has been reached the eye is never left in doubt however long we may be looking at the water. A check experiment in which the water with just a slight deficiency of silver, or excess of chloride, is used for comparison is therefore unnecessary. The plan is useful chiefly with very dilute solutions, one or two grains of chlorine per gallon, and since I have adopted it I have entirely given up the concentration of the water prior to titration formerly practised. A similar plan will, I think, be found useful in other titrations. Thus, in the case of turmeric, the change from yellow to brown is perceived more sharply and with greater certainty when looking through a flat cell containing tincture of turmeric of suitable concentration than with the naked eye. The liquid to be titrated should, as in the former case, be placed into a white porcelain dish. Again, in estimating the amount of carbonate of lime in a water by means of decinormal sulphuric acid and cochineal, the exact point of neutrality can be more sharply fixed by looking through the cell filled with a cochineal solution. In this case, the following is the plan I have found to answer best. The water to be tested-about 250 c.c.-is placed into a flat porcelain evaporating dish, part of which is covered over with a white porcelain plate. The water is now tinted with cochineal as usual, and the sulphuric acid run in, the operator looking at the dish through the cell containing the neutral cochineal solution. At first, the tint of the water and the tint in which the porcelain plate is seen are widely different; as, however, the carbonate becomes gradually neutralized, the two tints approach each other more and more, and when neutrality is reached they appear identical; assuming that the strength of the cochineal solution in the cell, and the amount of this solution added to the water, have been fairly well matched. Working in this manner I have found no difficulty (taking litre of water) to come within 0.1 c.c. of decinormal acid in two successive experiments, and the difference need never exceed 0.2 c.c. In the cell I employ, the two glass plates are a little less than half-an-inch apart. A somewhat similar plan may be found useful in other titrations, or in fact in many operations depending on the perceptions of colour change. ON THE DETERMINATION OF ORGANIC CARBON IN A WATER RESIDUE. BY FRANK P. PERKINS. Read before the Society of Public Analysts, on 2nd June, 1880. IN the Chemical News, for April 23rd, the second part of a paper by Mr. W. H. Perkin appeared, "On the Analysis of Organic Bodies containing Nitrogen," and as we read it, it occurred to us that the means there proposed may very readily be applied, and with some advantage, to the determination of organic carbon in a water residue, rendering what is now a somewhat tedious operation less troublesome. The determination of organic carbon by Dr. Frankland's method, undoubtedly elegant though it be, requires costly and easily deranged apparatus. That devised by Professor Dittmar an account of which is to be found in the Chemical News, for July 20, 1877, and * For the first part, see Chemical News, Dec. 26th, 1879. has also in Frankland's Water Analysis—while it does not require a special gas apparatus, rather a complex arrangement of tubes, and scrupulous attention must be paid to every detail in order to obtain uniform results. It is to this process we turn and endeavour to lessen the attendant difficulties. As it now stands, the process is essentially this-the residue is burnt in a current of purified atmospheric air, in a tube containing cupric oxide and a copper or silver coil. Of the gases evolved during combustion those not broken up and absorbed in the tube pass on through— 1. A small V tube, containing chromic and sulphuric acids. 8. A small weighed soda lime tube, where the carbonic anhydride formed during the combustion of the residue is absorbed. The preparation of the combustion tube takes some time, from the necessity, if copper be employed, of igniting the coil in hydrogen when first used. But we now have a mixture which will do double work and enable us to dispense with the copper or silver coil inside the tube, as well as the chromic acid tube outside. The author of the paper referred to has found that a mixture of potassic chromate and dichromate, together with cupric or manganic oxide (precip.), will break up the nitrogen oxides, and at a lower temperature will also absorb sulphurous anhydride. Directions for preparing the mixture are given by Mr. Perkin. In working, we have used both manganic and cupric oxide, and the cupric oxide has given the best results. Charge then a combustion tube of rather small bore and drawn out at one end, with the mixture, leaving room for the insertion of a platinum boat at its posterior extremity; let this end of the tube be connected with a bulb apparatus or a Woulffe's bottle, containing potash solution, and let its drawn-out portion be attached to the following arrangement : 1. AU tube filled with calcic chloride, the outlet of which is bent downwards at a right angle. 2. A straight tube filled with calcic chloride, the inlet of which is bent downwards at a right angle. 3. A small U tube filled with soda lime, and made in the following way : A piece of glass tubing, about 4 inch internal diameter, is drawn out at one end to a small neck. A loose plug of recently ignited asbestos is now inserted, pushing it up nearly close to where the tube begins to decrease in diameter. The tube is then bent into the U form, and after filling it with soda lime another asbestos plug is put in, and this end also drawn out. A short piece of caoutchouc tubing is slipped over each termination, and two stoppers of glass rod are fitted into the tubing. The U tube is now ready to be weighed. The one we use weighs about 16 grammes. The place it is destined to occupy is between the two calcic chloride tubes, but before attaching it the purity of the combustion tube must be proved. This is done by connecting the two calcic chloride tubes by a piece of caoutchouc tubing and the further one with an aspirator, and then drawing a stream of air, purified by passing through the potash solution, through the apparatus, the combustion tube being heated the while. When the air has passed for a time the rubber tubing is taken off, and a U tube, containing a little clear baryta water substituted in its place; if it is not rendered turbid, the tube is ready to receive the residue. All that now remains to be done is to turn off the gas from the furnace, to replace the tube containing baryta water, by the weighed soda lime tube, to introduce the platinum boat containing the residue into the combustion tube, to connect it again with the vessel containing the potash solution, and conduct the analysis in a stream of air in the usual way, taking care, however, not to heat strongly the front part of the combustion tube. When the combustion is over, the soda lime tube is disconnected, the little glass stoppers are again inserted, and it is weighed; the increase in weight gives the amount of CO, in the residue. In a few minutes the combustion tube is ready for another experiment, and may be used many times without further trouble. The following determinations will show the degree of accuracy attainable. A blank experiment gave an increase of 0.0005. In 1870, the same water analysed by Dr. Frankland gave, when— 0.218) 0.272 per 100,000. 0.164) REPORT ON THE ANALYSIS OF VARIOUS TINNED FOOD PRODUCTS. Second Paper. By G. W. WIGNER, F.C.S. The THE interest taken in my last paper induces me to publish some further results. subject grows rapidly in importance, for year by year the food producing power of England becomes less as compared with its food consuming power, while the rapid decrease in cost of transport by sea and land enables produce to be brought over distances of thousands of miles at a cost which is but small compared with the value of the commodity. In my last paper* I reported on one brand of tinned roast beef and one of boiled beef, and five other articles. I will commence again with meat. 8. Corned Beef (St. Louis Beef Canning Company). These tins are of a peculiar truncated pyramidal shape, which seemed at first calculated merely to increase the labour of tin making, but when a tin is opened it is found that the shape is advantageous, as the meat readily leaves the tin as if from a mould. The tins are very full, more so indeed than any other I have opened, and this should assist in keeping the meat. |