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CHEMICAL NEWS,}
Sept. 25,

Chemical Notices from Foreign Sources.

CORRESPONDENCE.

DETECTION OF NITRATES AND CHLORATES.

To the Editor of the Chemical News. SIR,-The following two new tests for the detection of nitrates in the presence of chlorates, and of nitrates apart from chlorates, will, I opine, be found very simple and effective.

Nitrates in Presence of Chlorates.-Put together in a test-tube KNO3 + KCÍO3 + H2SO4 (dilute) + excess of Cu foil. Place test-tube in a beaker holding saturated solution of NaCl, and heat to boiling. The chlorate being least stable is first decomposed, the liberated chlorine attacking the Cu, and a greenish gas given off. At a higher temperature, KNO, is decomposed and attacks the Cu, with formation of brown fumes. Nitrates Apart from Chlorates.-Put into a test-tube KNO3+Pb foil (shavings) + HCl (strong) and heat; KNO, is decomposed and attacks the Pb foil, with formation of Pb(NO3)2, which is again decomposed by the HCI, with formation of PbC12, and will be found as a white precipitate upon cooling.

One great advantage of this test lies in the fact that a nitrate can be detected in the presence of an iodide or bromide, because it is not dependent upon the formation of brown fumes, but upon that of PbCl2. Thus

Hg'2(NO3)2+NaBr+Pb foil + HCl=

free Br+PbCl2 precipitate on cooling. Again,Hg"I2+KNO3+Pb-foil + HCl =

free I+PbCl2 precipitate on cooling.-I am, &c.,

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165

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Revue Universelle des Mines et de la Metallurgie.

Series 3, June, 1891. Vol. xiv., No. 3. Purification of Industrial Waters and Sewage.A. and P. Buisine.-The authors prepare ferric sulphate from burnt pyrites by moistening them with concentrated sulphuric acid, so as to form a thick paste. If this is kept for some hours at 100-150°, with occasional agitation, the pyrites are covered with a whitish layer of ferric sulphate. It produces a more complete purification than does the addition of milk of lime. Water purified with ferric sulphate is perfectly clear, colourless, inodorous, neutral, or slightly acid. On the contrary, the effluent from the lime treatment is alkaline, coloured, retains an offensive odour, and rapidly becomes the seat of putrid fermentation. (Ferric salts have already been used for the treatment of sewage).

A New Method of Separating Iron from Cobalt and Nickel.-G. A. Le Roy.-In order to determine cobalt or nickel electrolytically, it is necessary first to remove any iron which may be present. The author effects this by bringing the metals into sulphuric solution, adding a very small quantity of a non-volatile organic acid, preferably citric. There is then added a large excess of a concentrated solution of ammonium sulphate, rendered strongly ammoniacal. Under these circumstances ferric hydroxide is not precipitated.

CHEMICAL NOTICES FROM FOREIGN

expressed.

SOURCES.

Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Vol. cxiii., No. 8, August 24, 1891. This issue does not contain any chemical matter.

MISCELLANEOUS.

"A Learned Judge! Mark, Jew, a Learned NOTE. All degrees of temperature are Centigrade unless otherwise Judge."-A case was tried at the Belfast Assizes last week in which the plaintiff complained that his clothes had been destroyed and his flesh burned, by reason of been served to him by the defendant. He had recovered the spilling of a corked bottle of aquafortis which had £3 as damages, but was fool enough to appeal against that amount as being insufficient, the result of which was that he got nothing, and had to pay costs. To those who know anything about aquafortis, it may appear strange that any doubt could arise as to the stupidity of putting up that liquid in a corked bottle, but the evidence went to show that it is a custom of the trade to send it out in such way, and the learned judge was certainly not learned on this subject, for he said that he "never heard of aquafortis affecting corks before."-Medical Press.

The

Vol. cxiii., No. 10, September 7, 1891. Direct Synthesis of the Primary Alcohols.- Paul Henry. Methyl alcohol, H3COH, is the primordial alcohol. The primary, secondary, or tertiary alcohols are derived from it by the respective substitution of hydrocarbon radicles CnHx for one, two, or three atoms of hydrogen. This general idea lacks experimental confirmation as far as the primary alcohols are concerned. author has supplied this deficiency by the reaction of the organo-zinc compounds upon the simple monoclinic methylic ethers. These, CIH2C-OCH3 and CIH2C-OC2H3, represent methylic alcohol, in which the hydroxyl group is rendered inactive in consequence of the replacement of the hydrogen by a hydrocarbon group, whilst the reactional aptitude of the chlorine is further heightened by the proximity of the oxygen. The monochloric methyl oxide, CH2C-OCH3, and its ethylic analogue react energetically upon the organic zinc compounds. these, enclosed in a flask filled with carbon dioxide and strongly refrigerated, chloric ether is let fall drop by drop. There results a thick mass, a mixture of ZnCl2 and of the ether formed. When the reaction is completed, water is added and the mixture is distilled. The yield of the operation is at least 90 per cent of the theoretical yield.

Into

100

Quantitative Determination of Pyridine Bases in Ammonia.-W. Kinzel (Pharm. Central Halle).-The author's method depends on the fact that pyridine and its alkyl derivatives, which in some respects are very similar to ammonia, form very unstable compounds with mercuric chloride, whilst ammonia forms more permanent basic compounds. The pyridine compounds are decomposed on heating and pass over into the distillate. grms. of ammonia are neutralised with sulphuric acid (1:5) with thorough refrigeration (using tincture of litmus as indicator), mixed with 1 drop of soda-lye, made up to 400 c.c., and distilled down to 2/3 in an hour. The distillate is mixed with 100 mercuric chloride in solution again made up to 400 c.c., and again distilled down to 2/3 in the same time. The solution is again titrated with decinormal hydrochloric acid to a red colour, using dimethyl orange as indicator. As a small quantity of

ammonia always passes over into the distillate, corresponding under the above conditions to o'8 c.c. of decinormal hydrochloric acid, this quantity must be deducted from the acid consumed. I c.c. decinormal acid corresponds to o'0079 grm. pyridine.

On a-Naphthol-Benzeïn as Indicator.-R. Zaloziecki (Chemiker Zeitung).-The author obtains this compound in the following manner:-2 mols. a-naphthol and I mol. benzotrichloride are diluted in a flask with a suitable quantity of benzol, so as to reduce the violence of the reaction which commences at ordinary temperatures and to yield a much purer product. After standing for 24 hours the reaction is completed by heating to 30-40°, and benzol and the excess of benzotrichloride are driven off by a current of steam. The mass thus obtained is purified by dissolving in dilute soda-lye and fractionated precipitation with hydrochloric acid. This is repeated several times, and finally the colouring-matter is thoroughly washed, and appears as a red-brown powder. Traces of alkalies dissolve a-naphthol-benzeïn with an intense green colour, which is turned to a reddish-yellow by dilute acids. This reaction is occasioned also by car. bonic acid, to which this indicator is extremely sensitive. Woollen tissue dyed green with this colouring matter is turned orange on exposure to the air or on rinsing with spring water. a Naphthol-benzeïn dissolves in alcohol with a reddish-brown colour. A I per cent alcoholic In solution is very well suited for volumetric purposes. its entire behaviour a-naphthol-benzeïn completely resembles phenolphthalein, the only difference being with carbonic acid, since on the addition of an acid to a car. bonate the change of colour takes place before the acid salt is formed.

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CHEMICAL NEWS, Oct. 2, 1891.

Didymium from Different Sources.

THE

VOL. LXIV., No. 1662.

167

ences, but they are certainly not such as I was led to CHEMICAL NEWS. expect from Krüss's papers, and they would require either quantitative measurements or direct comparison of the spectra to establish. I hope shortly to make a more careful comparison than I have as yet had time to undertake.

I am of course aware that no amount of negative results are of any value as against well-established posi

ON DIDYMIUM FROM DIFFERENT SOURCES.* tive ones, but I feel that some independent confirmation

By Professor C. M. THOMPSON.

IN the Berichte of date July 11th, 1887, Krüss and Nilson published observations on the rare earths producing absorption spectra, according to which almost every band observed was found to vary in strength in an independent manner, from which they drew the conclusion that the number of recognised elements must be very largely increased. These observations were continued by Kiesenwetter and Krüss, and the results previously obtained were confirmed.

The interest of these observations is chiefly in the fact that it is very difficult to fit such a number of elements into Mendeleef's system of classification.

It appeared to me important that the purely experimental part of this work should be confirmed or corrected, and as I was in possession of several of the minerals from which the earths may be obtained, I have tried to repeat the observations.

I naturally selected for investigation those minerals from which the most striking results had been obtained, and in order to make my remarks more definite I will confine myself to the consideration of what may be called the didymium fraction. With respect to this fraction, perhaps the most striking results were those obtained by Kiesenwetter and Krüss with the minerals yttrotitanite and gadolinite.

According to them the solution of the earths from yttrotitanite showed only three bands due to didymium, two of them falling together in the broad band in the yellow; the other in the green. Now these are the strongest bands seen with an ordinary didymium solution, and they would of course be seen alone with a very weak solution. I found it impossible to use directly a very strong solution of the crude earths for the examination of the didymium fraction-the bands due to other fractions are so overpowering. The didymium was, therefore, precipitated in the usual way with potassium sulphate. On examining the solution of the nitrates of the earths thus precipitated, I saw, much to my disappointment, what I should describe simply as an ordinary didymium spectrum. There remains the supposition that the mineral used by me was not the same as that used by Kiesenwetter and Krüss. I can only say that my mineral, like theirs, came from Arendal, and that it agrees in appearance with their published description. There are, however, two differences. The oxides of the earths got by me were of the usual fairly deep yellow colour; they describe their oxides as whitish grey with a tinge of yellow. Secondly, the number of bands not due to didymium, shown by a concentrated solution of my earths, is much greater than that mentioned by them, so that the whole spectrum is quite as complex as that shown by gadolinite earths.

According to Kiesenwetter and Krüss the earths from gadolinite from Hitterö show eight bands due to didymium. Separating the didymium fraction by potassium sulphate as before, I again obtained simply an ordinary spectrum. My gadolinite was from Hitterö.

I have further examined didymium from orthite and from monazite, and have been unable to observe any differences as compared with didymium from cerite which would justify me in concluding that the different bands varied in an independent manner.

I do not wish to deny that there may be slight differ*Abstract of a paper read before the British Association, Cardiff Meeting, 1891, Section B.

1

of Krüss's results is needed, and I can only hope that other chemists will be more fortunate in their material than I have been.

Notwithstanding the above remarks I am inclined to believe that the various bands which used to be ascribed to the one element didymium do vary in an independent

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DEAR PROF. TAIT,-I write to put on paper an account of the observation I mentioned to you to-night, in case you should think it worth communicating to the Royal Society of Edinburgh.

In the course of last summer I was led, in connection with some questions about lighthouses, to pass a beam of sunlight, condensed by a lens, through the flame of a candle. I noticed that where the cone of rays cut the luminous envelope, there were two patches of light brighter than the general flame, which were evidently due to sunlight scattered by matter in the envelope which was in a state of suspension. The patches corresponded in area to the intersection of the double cone by the envelope, and their thickness was, I may say, insensibly small. Within the envelope, as well as outside, there was none of this scattering. The patches were made more conspicuous by viewing the whole through a cell with an ammoniacal solution of a salt of copper, or through a blue glass coloured by cobalt. In the former case the light from the flame was more weakened than the scattered light, which was richer in rays of high refrangibility; in the latter case the patches were distinguished by a difference of colour, the patches being blue, while the flame (with a suitable thickness of blue glass) was purplish. The light of the patches exhibited the polarisation of light scattered by fine particles-that is to say, when viewed in a direction perpendicular to the incident light, it was polarised in a plane passing through the beam and the line of sight.

When a

When the beam was passed through the blue base of the flame there was no scattered light. A luminous gas flame showed the patches indicating scattered light like the flame of a candle, but less copiously. They were not seen in a Bunsen flame or in the flame of alcohol, but were well seen in the luminous flame of ether. glass jar was inverted over burning ether, the blue part, which does not show scattered light, extended higher till, just before the flame went out, the luminous part disappeared altogether. A Bunsen flame, fed with chloride of sodium, did not show the phenomenon, though the flame was fairly luminous.

Proceedings of the Royal Society of Edinburgh.

The phenomenon shows very prettily the separation of carbon (associated, it may be, with some hydrogen) in the flame, and at the same time the extreme thinness of the layer which this forms. It shows, too, the mode of separation of the carbon, namely, that it is due to the action of heat on the volatile hydrocarbon or vapour of ether, as the case may be. At the base, where there is a plentiful supply of oxygen, the molecules are burned at once. Higher up the heated products of combustion have time to decompose the combustible vapour before it gets oxygen enough to burn it, In the ether just going out for want of fresh air, the previous decomposition does not take place, probably because the heat arising from the combustion is divided between a large quantity of inert gas (nitrogen and products of combustion) and the combustible vapour, so that the portion which goes to the latter is not sufficient to decompose it prior to combustion.

In the Bunsen flame fed with chloride of sodium, the absence of scattered light tallies with the testimony of the prism, that the sodium is in the state of vapour, though I would not insist on this proof, as it is possible that the test of scattering sunlight is not sufficiently delicate to show the presence of so small a quantity of matter in a solid or liquid state.-Yours sincerely,

G. G. STOKES.

P.S.-I fancy the thinness of the stratum of glowing carbon is due to its being attacked on both sides-on the outside by oxygen, on the inside by carbonic acid, which with the glowing carbon would form carbonic oxide.

PROF. LIPPMANN'S HELIOCHROMY.* By F. E. IVES.

AT the March meeting of this Section I made some comments upon the alleged solution of the problem of photography in natural colours by Prof. Lippmann, of Paris, expressing some doubt as to the possibility of obtaining such alternate zones of "light and darkness" in proximity to the mercury mirror as are called for by Prof. Lippmann's theory, and also as to the possibility of reproducing the compound colours by means of interference lamina. I afterwards communicated my doubt to Prof. Himes, of Dickinson College, and asked for an expression of his opinion. He kindly wrote me a long letter, from which I quote as follows:

"As far as I have been able to follow Prof. Lippmann I am more hopeful than you perhaps are in the direction of compound colours, and more nearly satisfied with the theoretical explanation, although, of course, at this early stage it must be regarded, of course, only as provisional, and there are many questions that both of us would like to ask, some of which Prof. Lippmann might possibly be able to answer by this time, and others I am just as certain he could not. I will just note hastily the points upon which I have less difficulty and doubt than you seem to have, premising first that you concede the fact that Prof. Lippmann has succeeded in getting a photographic impression of the spectrum in which can be recognised at least the colours in their order,-some say brilliant and perfect, but I think Prof. Lippmann's account is more moderate and modest. But this is not the greatest feature of Prof. Lippmann's publication. This has been done long ago and by many, and possibly better than he has accomplished it, but he has succeeded in fixing it, and that by the ordinary photographic method, and his whole process, withal, is so simple and complete that it invites and encourages experiment with it, which I have great hope will lead to practical results.

"As to his theory we may think what we please. With

A communication to the Chemical Section of the Franklin Institute, April 21, 1891.

me it has this in its favour, that the appearance of all previously obtained heliochromic results by Becquerel and others, whether flowing from systematic investigation or from accident, as in many cases, conforms to that of Prof. Lippmann's results, and can be best described as that of interference colours. There are even those who intimate that after all Prof. Lippmann adopted a theory and line of investigation already outlined.

"I have no difficulty in regard to the interference of direct and reflected waves so as to produce so-called stationary waves of definite length and frequency. The ocular demonstration of such waves, usually employed in lectures, by means of a stretched spiral cord or gum tube, attached at one end to a hook, and held at the other end by the hand, on which regularly timed impulses by the hand produce interfering direct and reflected waves, is very satisfactory at this point. The completed analogue in case of sound is to me conclusive of the plausibility of the theory of Prof. Lippmann. Savort, in the early part of the century, and more recently Lord Rayleigh (in 1888), by a series of classical experiments, demonstrated the presence of stationary sound waves, with their spaces of sound and silence, by the interference of direct waves with those reflected from a board, using a sensitive flame to explore the space. A double reflecting surface may be necessary to present interference colours to the eye, as you state, as the rays should both be moving toward the eye; but to produce the stationary luminous undulations, or zones of maximum movement or maximum energy and zones of rest or of minimum movement, of the ether particles, the interference of an incident and reflected ray from one surface will be sufficient condition. These are hardly to be called zones of light and darkness. A ray of light is invisible as such; it produces visible effects, so here the zones of differing energy in the ether particles produce varying effects upon the film in which they are formed-effects which we recognise as photographic.

"These effects are not the production of pigment colours, as up to this time seems to have been the expectation in heliochromy, but they are rather in nature of change of structure, laminated deposits of silver, so

to say.

"As to the rendering of compound colours, I have not seen much claimed as accomplished in this direction. There is a well-grounded hope, I believe, but the rendering of the spectrum and the perfect fixing of it are the chief claims of Prof. Lippmann, as I understand it. I would not draw, or allow the theory to draw, the line of the impossible too near to the present achievement to prevent investigation and experiment with compound colours. The whole doctrine of perception of compound colours would not permit us to deny such possibility. Prof. Lippmann has certainly started scientific thought and investigation, as far as heliochromy is concerned, in a new direction, by results that command our admiration and a theory that is not only possible, but a most excellent working hypothesis."

Capt. Abney, who recently visited Prof. Lippmann, also appears to endorse his theories, but does not regard his process as a step in the direction of practical photography in colours. The following report of Captain Abney's remarks upon this subject, at the recent Camera Club Conference, is from the Photographic News of April 10th:

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Photography in natural colours was the next question to which the President turned his hearers' attention. The acccomplished fact,' as some of the newspapers led their readers to suppose, is as old as photography, for the discovery of photography in colours has been made, according to some people, over and over again. Being in Paris a week ago he had the opportunity of visiting M. Lippmann. He found that gentleman to be a true man of science, with all the modesty of a real investigator. The colour plates about which we have heard so much are due to interference, and not to pigments, and their effect varies according to the angle at which the plate on which they

CHEMICAL NEWS, Oct. 2, 1891.

"}

Action of Different Metals on India-rubber.

appear is held. Capt. Abney then proceeded to describe how these colours are obtained, by use of a mercury trough, as already detailed in our pages. He pointed out that, to obtain the colours, exposure to a bright spectrum was necessary, and that development must be brought about by alkaline carbonates, and the image intensified with silver. Both exposure and development must be exactly correct, or no colours are apparent, and the best results are gained with dry plates prepared with albumen and collodion. He looks upon the results of M. Lippmann's experiments merely as a verification of Newton's law, and not as a discovery of photography in colour. M. Lippmann has certainly succeeded in fixing interference colours, but the process is clearly one of extreme difficulty. It is a misfortune both for M. Lippmann and his prede. cessor, Dr. Koch, that their experiments should have been dealt with by the ordinary reporters, because these reports have led the general public to expect far more than the experiments in either case justified."

UNIVERSAL MICROSCOPIC EXHIBITION AT ANTWERP.

THE following particulars are obtained from the Chemiker Zeitung:

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The Exposition de Microscopie Générale, de Produits Végétaux et d'Horticulture" has just come to an end. It was projected by Dr. Henri van Heurck, Director of the Antwerp Botanical Garden, a microscopist of reputation. The plan of the promoters allowed of a strange mixture of products. Thus, along with brewed drinks, "schnaps " of all kinds (i.e., inferior liqueurs), were to be found pianos, mineral oils, guano and other manures. J. D. Möller, of Wedel, in Holstein, exhibited a collection of Diatoms, including not fewer than 4026 distinct forms. Not alone photographs of these species were on view, but the original specimens could be examined under a number of microscopes.

The firm Lumière and Cöller, of Lyon, exhibited coloured transparent figures of microbia, just as they appear to the eye under the microscope.

Along with microscopes there were exhibited stoves for the cultivation of bacteria, apparatus for sterilising, &c. Among the exhibitors of instruments a prominent place belongs to the establishment of Carl Zeiss, of Jena. Their display included a selection of microscopes, from the simplest to the most complex, combined with appliances for photographic projection, a set showing all the single parts of which a perfect microscope is composed, and a collection illustrating the production of lenses from the crude glass through every stage of grinding.

Watson and Sons, of Holborn, exhibited a large selec tion of microscopes for various purposes, especially an instrument made according to the indications of Dr. van Heurck, adapted for delicate researches and for photomicrography.

M. Nachet, of Paris, displayed instruments for research, general, scientific, and technical.

Powell and Lealand, of London, exhibit a large microscope, said to be the most perfect as regards its stand. Hartnack, of Potsdam, had microscopes and objectglasses with photo-micrographic fittings. J. Deby, of London, displayed a collection of instruments by various modern makers with manifold appliances for illumina tion, arrangements for obtaining monochromatic light, as also a rich and interesting collection of preparations. Adnet, and also Wainsegg, of Paris, and Siebert, of Vienna, exhibited a variety of bacteriological apparatus.

It strikes us as remarkable that no spectroscopic apparatus seems to have been exhibited.

The Chemiker Zeitung remarks, with perfect justice, that it is impossible for an expert to pronounce on the value of any instrument so long as it can only be seen in a glass case.

ON THE

169

ACTION OF DIFFERENT METALS, METALLIC SALTS, ACIDS, AND OXIDISING AGENTS ON INDIA-RUBBER.*

By WILLIAM THOMSON, F.R.S.Ed., &c., and
FREDERICK LEWIS.

A FEW years ago one of us studied the influence of different oily and greasy matters on india rubber. (Journal of the Society of Chemical Industry, 29th December, 1885), and at the meeting of the British Association in Leeds we called attention to the distinctive effect which both metallic copper and all the salts of copper exercised on india-rubber. In the present paper we have carried these experiments further, with a view of obtaining more accurate information as to the effect of copper and its salts, and also that of other metals and their salts, and other agents, on india-rubber.

The method we adopted was to take a fine sheet of india rubber spread on paper and vulcanised by the cold process with a mixture of chloride of sulphur dissolved in bisulphide of carbon. By this arrangement it was easy to tell the effect of different substances on the rubber on breaking the paper between the fingers, the fine sheet of caoutchouc being left free so that it could be stretched, and a fair idea obtained as to whether its elastic properties had been damaged.

Action of Metals on Rubber.

The first series of experiments was made with different metals reduced by means of a file to a fine state of division, the file employed being first thoroughly cleansed, and then washed with ether, to remove any oily or greasy matters from it. Small pieces of 3 inches square were cut from a large piece of the above-mentioned fine sheet pure Para rubber, and thin layers of the filings of the different metals were spread over about 1 inches square of the centre. These were then placed together in an incubator, kept constantly at a temperature of 140° F. by means of a thermostat, night and day, on glass shelves, and every day the positions of the pieces so treated were altered, so that those in the middle were placed nearer the sides, which we thought might possibly communicate more heat than might be received in the middle. ten days the rubber on each square was tested in the manner above indicated. This series of experiments was repeated, and the following results were obtained:-

After

One of the metals had a destructive effect on rubber far beyond any of the others, and that was copper. As compared with copper the following metals had a comparatively slight effect, although they exercised an injurious influence. They are given in the order of the injurious influ ence they exercised:

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