In order to distinguish genuine butter from so-called oleomargarine, Hager, we read, saturates a cotton-wick with the melted sample, lights, and allows it to burn for two minutes, and judges its quality by the smell. Artificial butter gives the well-known offensive odour of an extinguished tallow candle.— Provisioner.

A public laboratory for the analyis of anything sold as food has been established in Paris by the Prefect of the Seine, the fees being limited to from five to twenty francs, according to the difficulty of the operations.—Provisioner.

Dr. Ebenezer Evans has been appointed Public Analyst for the county of Anglesey, at one guinea per analysis, vice Owen, resigned.

Mr. James Napier, F.C.S., has been appointed Public Analyst for the borough of Sudbury, at five guineas per annum and fees.

Mr. A. W. Stokes, F.C.S., has been appointed Public Analyst for the parish of St. Matthew, Bethnal Green, vice Tidy, resigned.

RECENT CHEMICAL PATIENTS.

The following specifications have been recently published, and can be obtained from the Great Seal Office, Cursitor Street, Chancery Lane, London.

2902 B. H. Remmers & J. Williamson Refining or Purifying Sugar, &c.

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; Sanitary Engineer of New York; The Cowkeeper and Dairyman's Journal; The Chemists' Journal; Oil and Drug News; The Textile Record of America; Sugar Cane; Practical Chemistry, by Hurst & Madan.

A GENERAL MEETING of this Society was held at Burlington House, on Wednesday, the 16th March, the President, Mr. Heisch, in the chair.

The President announced that in accordance with the resolution passed at the Extraordinary Meeting, held on the 16th February, the Council had elected Mr. F. Maxwell Lyte, as the second secretary of the Society for the remainder of the current year. Mr. Lyte was too well known for it to be necessary for him to say one word, except that it was a very good thing for the Society to have obtained his services.

A letter from Monsr. E. Chevreul, accepting the Honorary Membership, was read and ordered to be entered on the minutes, and that letter and those from Dr. Hofmann and Professor Fresenius, which were read at the previous meeting, were, if possible, also to be published.

Dr. Bartlett and Mr. B. Dyer, having been appointed as Scrutineers to open the ballot papers, announced that the following gentlemen had been elected :-As MembersJohn Parry, Public Analyst for Penryn; W. D. Sykes, M.D., Public Analyst for Portsmouth; H. Liepmann, Ph.D., F.C.S., Analytical Chemist, of Leadenhall Street, London. As Associates-W. Fox, Assistant to Mr. J. Baynes, of Leeds; D. A. Sutherland, Assistant to Dr. Drinkwater, of Edinburgh.

The following gentlemen were proposed for election as Members, and will be balloted for at the next Meeting:-W. L. Emmerson, M.D., &c., Public Analyst for the County of Leicester, &c.; H. Meadows, M.B., Public Analyst for the Borough of Leicester; R. Oxland, F.C.S., Public Analyst for Plymouth and Devonport; W. F. K. Stock, Public Analyst for Durham.

The following papers were then read and discussed: the Sale of Poisons," by C. Heisch, F.C.S., F.I.C.

"The Swedish Acts for regulating

"Some Analyses of Milk," by Bernard Dyer, F.C.S., F.I.C.

"On Samples of Milk which have fallen below the Society's Standard," by J. Carter Bell, F.C.S., F.I.C.

"On a New Method for the Estimation of Nitrates in Potable Water," by J. WestKnights, F.C.S.

"Nitrates in River Waters," by F. P. Perkins, F.C.S.

The following are the letters from the recently elected Honorary Members referred to above :

MUSEUM D'HISTOIRE NATURELLE, PARIS, 18 de Février, 1881. CHER MONSIEUR,-Après avoir lu votre lettre, et pris connaissance du groupe des Savants auxquels le Conseil de la Société a bien voulu associer mon nom, on ne peut croire, quel que fut l'opinion que l'ou ent de la valeur de ses propres travaux, qu'on se trouva pas honoré d'appartenir au groupe des honoraires

de la Société nouvelle. Veuillez donc, Monsieur, donner connaissance de cette lettre,-en réponse à celle que vous m'avez adressée, au Conseil de la Société, afin qu'il sache, de moi-même, que celui qui s'honore du titre de doyen des étudiants de France, ne peut que s'honorer du titre de membre honoraire de votre Société. Si ma vie scientifique a été heureuse, c'est d'avoir eu de la nation Anglaise, qui a été si grande, a mon sens, dans toutes les branches des connaissances humaines, des titres de son estime, pour des travaux dont le but, en toutes choses, a été la verité. Que le Conseil sache donc, combien je en’honore d'être le doyen des associés étrangers de la Société Royale de Londres, comme je la suis de l'Académie des Sciences de l'Institut de France, et quelle m'ait jugé digne de lui appartenir.

Veuillez, Monsieur le Secrétaire Honoràire, agréer l'expression de mes sentiments de haute et profonde estime. E. CHEVREUL.

10, Dorothein Strasse, Berlin.

DEAR SIR,—I hasten to acknowledge the letter informing me of the great distinction the Society of Public Analysts have conferred upon me by electing me their Honorary Member. I deem it indeed a great honour to belong to so important and useful an association as the Society of Public Analysts has rapidly become, and this honour in my eyes is doubled by its coming from dear old England, so long the country of my adoption, and of which as long as I live I shall always bear a most grateful recollection.

Will you be so good as to convey the expression of heartfelt thanks to my new colleagues for the honour they have done me.

G. W. Wigner, Esq., Hon. Sec. Society Public Analysts.

A. W. HOFMANN.

And believe me, dear Sir, ever yours very sincerely,

Wiesbaden, 10th February, 1881.

DEAR SIR,-In receipt of yours of the 5th inst., I shall be glad to accept the election as an Honorary Member of your esteemed Society, by which you pay a great compliment to my researches in analytic chemistry.

Accept my best thanks on behalf of yourself and your Society for the honour you confer on me. With compliments, I am, yours truly,

G. W. Wigner, 79, Great Tower Street, London, E.C.

C. R. FRESENIUS.

The next Meeting of the Society of Public Analysts will be held at Burlington House, on Wednesday, the 13th April.

ON A NEW METHOD FOR THE ESTIMATION OF NITRATES IN POTABLE

WATER.

By J. WEST-KNIGHTS, F.I.C., F.C.S.

THE most delicate test we have for nitric acid is undoubtedly the brucine test, and perhaps it is one of the most delicate tests in the whole range of analytical chemistry, for the red colour produced by it from one part of nitrogen as nitrate, is distinctly perceptible when diluted with ten million parts of water and yet, so far as I am aware, this test has never been made a quantitative one.

4

This may, perhaps, be accounted for in the fact that in using this test in the ordinary way, with excess of HNO, (as in testing for brucine), or with excess of H2SO, (as in testing for nitrates), the red colour is destroyed almost as soon as produced, the result being an orange or brown colour, the intensity of which is diminished, or the colouration altogether disappears.

But if certain precautions be taken the blood-red colour is perfectly permanent.

If oxalic acid be employed instead of sulphuric, in applying the test to nitrates, and provided that the nitrate is not present in greater proportion than one molecule of NO, to

one of brucine the red colour is produced permanently, not only from nitrates of the alkaline earths but also from nitrates of the alkalies.

To apply this to the estimation of nitrates in water, it is merely necessary to evaporate a measured quantity of water to dryness, moisten the residue with solutions of brucine and oxalic acid, again evaporate to dryness, dissolve the red residue in water, filter and compare the colour with a standard red colour, produced in the same way from a weighed quantity of nitrate of potash. The solutions required are:

Nitrate of Potash Solution.-721 grm. of pure nitrate of potash are dissolved in one litre of distilled water; one c.c. of this solution contains ⚫0001 grm. of nitrogen as nitrate. Brucine Solution.-Dissolve one grm. of brucine in 100 c.c. of alcohol; each c.c. contains 01 grm. brucine.

Oxalic Acid Solution.-A cold saturated solution.

Standard Red Solution.-Evaporate 10 c.c. of nitrate of potash solution to dryness in a platinum dish over a beaker of boiling water, moisten the residue with 3 c.c. of brucine solution and about 6 drops of oxalic acid solution, and again evaporate gently to complete dryness, moisten the red residue with a few drops of distilled water and once more evaporate to complete dryness, dissolve the residue in a little distilled water on the water-bath, wash the solution into a hundred c.c. flask and fill up to the mark with distilled water. This solution should have a bright red colour, with no appearance of orange or brown even when considerably diluted; 1 c.c. is equal to 00001 grm. of nitrogen as nitrate (the same strength as the dilute ammonia used in nesslerizing).

The sample of water is now prepared in a similar manner: 10 c.c. are evaporated to dryness, and brucine solution added to the residue in sufficient quantity, from 0.5 c.c. to 2 c.c. according to the quantity of nitrate present. It is advisable not to have a large excess of brucine, but it is absolutely necessary for the production of a full red colour that there should be a slight excess, or at least an equivalent. As a first trial 1 c.c. may be used, which will generally be found sufficient, but if the colour produced is a decided brown and not comparable with the standard red, a fresh quantity of the water must be taken and more brucine solution used until the result is satisfactory; if on the contrary, a very slight pink colour is produced, indicating 1 or 2-10ths of a grain of nitrogen as nitrates per gallon, a smaller quantity should be used. Three or four drops of oxalic acid should be added and the whole gently evaporated to complete dryness, moisten the residue, which, if enough brucine has been used will be perfectly red, with a few drops of water and again evaporate; now dissolve the residue on the water-bath in a little water and filter into a white glass cylinder marked at 50 c.c. and fill up to the mark with water; now imitate the colour exactly in another cylinder by using from 1 c.c. to 10 c.c. of the standard red made up to 50 c.c. with water. If the colour produced by the 10 c.c. of water is deeper than that produced by 10 c.c. of the standard red, it must be diluted with one or two volumes of water and 50 c.c. used as before; if it is lighter than 1 c.c. of the standard, then 20 c.c. or 30 c.c. of the water must be evaporated instead of 10 c.c.

When 10 c.c. of water are used, the number of c.c. of standard red required to produce a similar tint multiplied by 7 and divided by 100 equals grains per gallon of nitrogen as nitrates.

Although so small a quantity of water as 10 c.c. is employed for the estimation of nitrates by this method, and in fact 1 c.c. may be used in some cases, it is fully as accurate

as the aluminium method, for although in that method a much larger quantity of water is taken initially, the actual estimation takes place in the same amount as in the brucine method, and not only is the red colour more striking to the eye than the yellowish-brown colour in nesslerizing, but it is also permanent and does not change on standing.

I give below estimations of nitrates in two samples of water both by the brucine and aluminium methods, the samples were selected as giving a fairly low and a very high proportion of nitrates respectively.

I regret I have not had time to bring forward a larger number of analyses to support the accuracy of this process, but the whole operation is so simple and speedy that I am led to hope that some of the members of this Society, especially those that are connected with the water scheme, will give it a fair trial and communicate the results to the Society.

ON THE ESTIMATION OF NITRATES IN RIVER WATER.
BY FRANK P. PERKINS.

Read before the Society of Public Analysts on 16th March, 1881.

MANY are the processes that have been devised for the estimation of nitrates; nevertheless, the method here described may, perhaps, be found worthy of your consideration: not the less so from its constancy and extreme simplicity. I have observed that if 100 c.c. of the water to be examined are put into a perfectly bright and freshly ignited platinum dish, together with a very small portion of sodium chloride (the commercial salt may be used if previously ignited to get rid of any trace of organic matter it may contain), on introducing into the saline liquid a coil of magnesium (made from a piece of ribbon about three feet in length by simply coiling it round a glass rod, and subsequently cleansing it from oxide by immersing it in dilute hydrochloric acid and washing with water), immediately that contact between the platinum and magnesium is gained, electrical action ensues and the water is decomposed. At first the action is somewhat slow, but in a very few minutes a torrent of minute gas bubbles ascends through the liquid. Should the water contain nitrates these are reduced-through the action of the nascent hydrogen-and converted into

A slight elevation of temperature considerably hastens the decomposition, but in practice nothing is gained by this. During the experiment the platinum dish is covered with a clock glass, then placed on a plate of ground glass, and for further security a small bell jar, the mouth of which is also ground, is inverted over it, contact with the air being thus in a great measure prevented. Thus it rests during the night, or until the whole of the magnesium is dissolved. The convex surface of the clock glass is then rinsed with pure