Imatges de pàgina
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it into one of those colours that I say it is capable of quenching, it will become black. Now observe. Here in the red ray we have the red very beautiful indeed, but the green is made quite black. Now I move the flowers into the green portion—what are they now? Black. And here, again [moving the flowers into the led light], they are a beautiful bright red. The green light is much more intense to look at than the red light, but this substance is not capable of giving back the green light: it is only capable of giving back the red light. The consequence is, that when the green light falls upon it its colour is destroyed—we have darkness instead of light. Here we have three sticks of sealing-wax, beautifully red. What are they now? [Placing them in the green part of the spectrum.] Look at them now: the light shining on them is very intense, but the sealing-wax is quite black.

Now, with regard to the influence of this coloured light upon the human countenance, I wish I cou'.d get some boy, in all the bloom of rosy youth, to let me try the influence of the light upon his cheeks. You would see how he would look in this green light. I wonder whether any of my pupils will volunteer. Huwever, in the absence of a volunteer, I will take Mr. Anderson; he has a tolerably fair colour, you know. He will stand here, and I will illuminate his face. I dare say I shall succeed in making one cheek appear full of the bloom of youth, and in reducing the other to a state of almost death-like paleness. Let us see if that is not possible. [Mr. Anderson then walked slowly along the coloured rays of the spectrum.] There, you see his face is full of radiant bloom, As he passes along, you will find one side of his face will assume a very cadaverous aspect. He will go back again so as to show you the effect produced: by-andby his whiskers will become quite radient—now he is in the midst of the red ray—there, he is in almost the full splendour of boyhood.

Now, I want to show you some of the spectra produced by the combustion of various kinds of metals. Hitherto, as you have observed, we have been dealing with a spectrum or coloured image, that was quite continuous from beginning to end, commencing with the red, and passing through various gradations to the extreme violet; it was continuous, there was no breach of the spectrum. I want now to show you some spectra where there are the most singular breaches of continuity, and to do this I Operate thus:—You know the energy of this electric current we use for our light; you know its power to render metal white-hot, and even to dissipate it, and to reduce it to a state of vapour. Here I have a small piece of caibon, and on the top of that I have scooped a little hole, anil into that hole I will put a little bit of metal. The metal I take is cadmium, well known to chemists. When I bring this little crucible close to our coal point and send the current through it, the metal will become intensely heated; it will, in fact, be reduced to a state of vapour. In the first place, I want to show you the light produced by this cadmium. I will take away the ordinary coal point which I have used for the light and place in its stead this crucible of carbon. I will then place within it this bit of cadmium, and bring down the upper coal point to meet it. I want you to observe the beautiful coloured light produced by this cadmium. You have already seen the image of the coal points that we have worked with throughout the lectures; I want to show you the distinc tion between this image of the coal points and the image produced when we introduce a metal into the electric current. You see the splendid blue light produced by the combustion of the metal; it is entirely different from the voltaic arc we have been hitherto operating with. Instead of this cadmium I will take a little copper, and then a beautiful green light will be produced, due to the vaporisation,—the reduction of the copper to a state of utter vapour. We may take gold or silver and produce similar effects. The green light issuing from the copper

is most beautifully shown passing along the smoke of the room. Now, I want to examine that light which is thus given out by the copper,—that is, I want to produce a spectrum of that light. And when I do so you will find that this spectrum, instead of being continuous, as in the former case, now consists of a series of brilliant bands of light, and in particular you will notice the very brilliant green bands produced by it. There you see the spectrum produced by the combustion of the copper, and the beautiful green bands we have already noticed, with the dark spaces between. I will now take another metal instead of copper. I will place a bit of zinc upon the crucible, and just be kind enough to bear in mind the kind of ban'ls you saw with the copper; they were chiefly green, while those that you now see produced by the zinc are of a brilliant blue. You see the spectrum covered with these blue bauds. Now, I will take a substance formed by the mixture of zinc and copper, that is, brass, and in the spectrum produced by the combustion of that brass I trust you will be able to see the bands of both the metals of which it is composed. You remember that copper gave a series of green bands, and zinc a series of blue bands, and I hope in the spectrum of the brass, if we are skilful enough to make the experiment aright, we shall see both the green of the copper and the blue of the zinc. In this way, knowing the character of the spectrum, we can tell the metals of which it is composed. Now, I want to show you another very beautiful experiment before we part. In the first place, I will show you the light produced by the combustion of a little sodium. I have hero a portion of this metal, which I can cut with a knife, like cheese. I have here a lamp, giving a strong heat, but very little light, and I will take a portion of this sodium and put it upon a little platinum cup and hold it in tl.e flame of this lamp, and then 1 think you will see that the sodium has the effect of giving a very intense yellow light indeed. Let us see whether we can produce this. At the best of times I have not much colour, but what little I have will certainly disappear if I cause this light to become more intense. That light does not only appear yellow, but it has actually no red in it at all. Look at the red sealing-wax, and at that bottle; that bottle contains iodide of mercury, which is of a brilliant red colour, but you see the red is now completely gone.

I want, now, to make a very peculiar experiment. I want to show you thot that very yellow light which you saw there is rapable of cutting off the yellow light that emanates from the electric lamp. In order to do that, I must first of all produce a continuous spectrum, such as we had before. I want to get it very exact, for the experiment is an important one and worthy of some labour. The experiment I am going to make is this. You saw that beam issuing from the lamp, and the spectrum produced from that beam upon the screen. I will send that spectrum through the sodium flame, and you will find that that flame will be capable of chiselling or cutting out with the greatest nicety the yellow portion of the spectrum. I want you particularly to observe the action of this piece of sodium upon the flame. I want you to observe the yellow part of that spectrum when I introduce this metal. A certain duskiness will come over the yellow portion there. Do you see how it cuts out the yellow of the spectrum r Here, in the platinum spoon, I have a quantity of soda produced by the combustion of the sodium. I will pour this soda upon one of the coal points, and you will then see that it produces a yellow line exactly where it formerly cut it out. Thus, the sodium flame is capable of absorbing those particular rays of light which its. If can emi .

I do not know that any more time remains to me to make experiments, but I will just carry you, in conclusion, to consider what has been done by experiments of this kind. When we take, instead of the electric light, the light of the sun, there are certain lines always

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observed in its spectrum. These lines have been compared with the utmost exactitude with the band9 produced in the spectra of various terrestrial metals, and have been found exactly to coincide with them. In this way the actual composition of the sun has been proved by a very able man, a Oerman. It is a wonderful thing to see the human mind, as it were, rising up to the sun itself, and being able to tell us, from the very lines that you see in the solar spectrum, the metals that are present in the sun. And not only so, but the experiments have led us to several conclusions regarding the nature of the sun; and we now know, which is very different from the conclusion adopted formerly, that the sun consists of a vast central ■olid or liquid sphere, in a state of high incandescence,— burning hoi. Round this sphere there is a great atmosphere, like a vast flame; the rays of the central solid or liquid portion of the sua have to pasB through this fiery flame, and in that atmosphere certain of the rays are quenched and destroyed, exactly as the flame of the sodium quenches or destroys the yellow band of the electric light. Thus, from the lines in the solar spectrum, wo can infer that iron, magnesium, and a great many other metals which are well known upon the earth are present in the sun.

NOTICES OF PATENTS.

895. Sating or Preparing Paper and Textile Fabrics in order to render them Waterproof, and to increase the strength thereof. R. A. Brooman, Fleet Street, London. A Communication. Dated April 11, 1861, For carrying out the objacts specified in the title, the inventor clnims the use of a mixture of carbonate of soda, lime, alum, and gamboge, which ingredients may either be incorporated with the pulp, or used subsequently to the manufacture of the paper.

The combination of gamboge and alumina is brownish yellow in colour, and must therefore communicate a somewhat dark tinge to the paper stuff.

911. Improvements relating to Ornamental Cotton Fabrict,

having Turkey Red Grounds. G. Graham, Dumbarton,

N.B. Dated April 13, 1861. The mode of proceeding described in the specification, is substantially as follows :—The goods, after dyeing uniformly with turkey red, are subjected to pressure between lead plates, from which the required device is cut out. Thus partially protected, the red portions are bleached by exposure to chloride of lime and sulphuric acid. This having been effected, the material is well washed by a current of pure water passing through it, and then a mordant applied to the bliached surfaces, either wholly or partially, according to whether it is desired to leave some parts of the fabric white. The mordant may be any one of those commonly employed, but the inventor recommends the use of a mixture of acetate of lead and bichromate of potash, of a strength of about two and a-half degrees Twaddell. Logwood liquor, of the same gravity, is finally passed through the goods to prcduce a black dye.

It is manifest that numerous combinations of turkey red, white, yellow, and black may be obtained according to the mode of employing the series of perforated lead plates.

The second part of the invention relates to the production of continuous patterns, by the employment of blocks or rollers.

929. Manufacturing Silicate of Lime, or Hydraulic Cement.

F. M. Eden, Hare Court, Temple, London. Dated

April 16, 1861. (Not proceeded with.) Fob the preparation of a cement, (which is stated to be chemically identical with Portland cement,) the inventor

directs an intimate mixture to be made of chalk and clay. Carbonate of lime, or the same burnt to lime, may be employed indifferently. This mixture is then dried and burnt upon hot tiles or plates, or in suitable ovens or kilns, and the product (called silicate of lime,) ground to an impalpable powder.

Portland cement is usually prepared according to a process very similar to that under consideration, the mud from the river Thames being taken in preference to more compact clays. If chemically identical with the product of ordinary manufacture, the cement must contain a large proportion of alumina, derived from the clay, and would, consequently, be more correctly described by including the two bases in the expression, and calling it a silicate of alumina and lime.

927. Obtaining Light. F. Gye, Wandsworth Road.

Dated April 15, 1861. In the arrangement of apparatus for the production of the lime light, the patentee claims the application of discs or plates of lime, instead ot the usual balls or cylinders, and the imparting rotation to the same by means of a new combination of mechanism.

932. Improvements in the Manufacture of Nitric Acid and Caustic Soda. J. D. Malcolm, Brixton, Surrey. Dated April 16, 1861. (Not proceeded with.) ■

The inventor mixes intimately one part, by weight, of nitrate of soda with three parts of fine clean sea sand, introduces the mixture into an earthen retort, and proceeds to distil as in the ordinary process of preparing nitric acid with the aid of oil of vitriol. The red nitric fumes are absorbed by water contained in a series of stoneware Woulfe's bottles, and the soda is said to remain in the retort partly in combination with silica, but principally in the form of caustic soda, which may now be recovered by washing the residual matter (sand and alkali;, and evaporating the aqueous solution in order to procure caustic soda; the sand left insoluble may be dried and used in a repetition of the process.

A question of greater importance than the economiaati m of the sand has reference to the durability of the retorts themselves under the corrosive action of so powerful an alkali, the destructive influence of which would even be materially assisted by the elevated temperature required for the distillation under these circumstances. The distillation of saltpetre with sand and clay was precisely that process which led to the first discovery of aqua fortis. It has not, however, of late years been resorted to for the manufacture of nitric acid on account of the partial decomposition of the product at the high temperature at which it is liberated. As an illustration of the antiquity of this method, we quote from Bishop Watson's Essays,1 published in 1789,—"It is certain that the nitrous acid may be disengaged without the assistance of the vitriolic acid: thus I remember having many years ago obtained a very strong fuming acid of nitre by distilling nitre with white Band."

Grants of Provisional Protection for Six Months.

2917. Francis Puis, Francis Terrace, Hackney Wick, London, "Improvements in treating fatty and oily matters."—Petition recorded November 20, i86r.

3027. Andre Marie Augustin Pichery and Pierre Louis Danais, Nantes, Loire Inferieure, France, "Improvements in hermetically stoppering or covering jars, pots, vases, and other like articles."—Petition recorded December 3, 1861.

3076. Balthasar Wilhelm Oerland, Newton le-Willows, Lancashire, "Improvements in the manufacture of sulphate of copper and other salts of the same metal."—Petitions recorded December 7, 1861.

1 Chemical Essays. Vol. I. p. 153.

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3142. Eduard Claude Barbotte de Beaulieu, Avallon, Yonne,France, "Improvements in apparatus for extracting gold dust from auriferous sands."

3150. Emile Cajot, St. Servais, Belgium, "Improvements in the treatment of pyrites for the manufacture of iron."—Petitions recorded November 14, 1861.

3195. Vasco D'Almeida, Nottinpham-street, Marylebone, London, "An improved mode of obtaining colouring matter applicable to dyeing skins, silk, wool, and other fibrous materials."—A. communication from Edward Smith, Place Cruzquebrada, Lisbon.

3115. Francois Laurent acd John Casthelaz, Rue St. Croix de la Bretonnerie, Paris, "Improvements in the manufacture of colouring matters."

3232. Joseph Schloss, Cannon Street, London, "Improvements in envelopes for containing photographic portraits and pictures."—A communication from Simeon Schloss, Paris.

3257. William Edward Newton, Chancery Lane, London, "Improvements in the manufacture of cube sugar."—A communication from Gustavus Finken, Brooklyn, King's County, New York, U.S.

3259. Alexandre Isaac Austen, Millwall, Middlesex, "Improvements in the manufacture of night-lights."— Petitions recorded December 30, 1861.

CORRESPONDENCE.

Manufacture of While Lead.
To the Editor of the Chemical News.

Sib,—If your correspondent " Subscriber," in your last Number, will favour us with his address, we shall be happy to supply him with white lead (the pure carbonate), either in a dry state or ground in linseed oil, perfectly fine and free from the defects he mentions.

AVe are, &c. W. AV. And R. Johnson And Sons. Wbito Load Works, Limehouso, London.

MISCELLANEOUS.

Chemical Society.—The next Meeting of this Society will take place on Thursday, the 6th inst., when the following Papers will be read :—Mr. Adie, " On Ground Ice." Dr. Bence Jones, "On Crystalline Xanlhin in Human Urine." Mr. A. H. Church, " On Silica." Professor Bloxam, " On Arsc*nic in Sulphuric Acid."

Itoyal institution.—The following Lectures will be delivered in the ensuing week :—Monday, February 3, at two o'clock, General Monthly Meeting. Tuesdav, February 4, at three o'clock, John Marshall, Esq., '• On the Physiology of the Senses." Thursday, February 6, at three o'clock, Professor Tyndall, "On Heat." Friday, February 7, at eight o'clock, T. H. Huxley, Esq., " On Fossil Remains of Man." Saturday, February 8, at three o'clock, Rev. A. J. D'Orsey, " On the English Language."

Adulteration of Food—Dr. Lethcby, the Medical Officer to the City Commission of Sewers, states in his quarterly repoit that no application has been made to him during the quarter for the analysis of food or dri k, and he adds that " it is to be feared, from the experience of the last six months, that the Adulteration of Food Act will become a dead letter."

Science a Civlliter—Dr. J. Bullar at a recent meeting of the Southampton Microscopical Society, said :— "The social aspect ol our Society commends it. It is a pleasant way of spending an evening where there is a scientific object of natural interest, and, at the sama time,

a social gathering of many haying the same tastes and objects, and, therefore, the same sympathies. The anatoniy of an insect, too, is a more harmless occupation than the minute dissection of a neighbours natural history. Tea and coffee, pleasant chat with those of like tastes, and then the table covered with microscopes and specimens explained by one and passed round for each to examine, calling out animated talk on subjects worth discussing, or a short paper read and discussed on the subject illustrated, are civilizing. For science is a civilizer. It refines the tastes and elevates the thoughts, as it is the search after truth for truth's own sake. And in this age, when the progress of the nation and of the world iB estimated by the moneyvalue of exports and imports (and in this aspect the world's progress is piodigious and annually increasing), the danger must lie in estimating all things in reference to money rather than to truth. Now, science is a counteracting force. It neither brings wealth to its true cultivators, nor can wealth buy scientific tastes or scientific fame. Itbelongs to a higher region than 'the diggings.' It must breathe ' a purer ether, a diviner air.' And those who are engrossed in commerce would often do well, for their own content and happiness, by seeking in the recreations of science a complete change of action, thought, and feeling. Obviously the eye service which the microscope requires, trains the eye to minute and discriminative observation, and the hand to delicate accuracy. It leads on, if used scientificallv. to the improvement of the scientific powers. Thememory, the investigation of causes, the estimation of evidence, the power of distinguishing and of generalizing may be called into activity. But the mind has other and deeper needs than these. The senses lead to the awakening and culture of deeper powers inherent in the soul itself, and the microscope may excite and cultivate, not only the sense of the true, but of the beautiful. Constable, the landBcapepaiuler, said that, pictorially, nothing in nature was ugly; and surely we may say the same microscopically. The higher the magnifying powers, the more minutely extensive the investigations, the more beauty do we see. Even in the unhealthy secretions—in what look to the unscientific eye like repulsive fluids, in the very disorganisations which slowly ruin this goodly human frame, the microscope discover* forms of the highest geometrical accuracy, as well as of the most delicate beauty. And this beauty and consummate finish are (verywhere, and are found (art! cr and deeper as our powers increase of observing them. Here, too, at every step we find the limitation of our own powers, and the illimitable field of nature ; the infinite contrasting with the finite, teaching us 'the moral lesson of science—humility.'"

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ANSWERS TO CORRESPONDENTS.

*,* All Editorial Communication! are to be addressed to the Eoitok • and AdvertitcmenU and Business Communication* to the Publish m at the Office, 1, Wine Office Court, Fleet Street, London, K C

Vol. IV. of the. CumiCAL News, containing a copious Indox is now ready, prico us., by post, lis. 8d., handsomely bound in cloth goldlettered. Tbo cases lor binding may be obtained at our Office' price is. 6d. Subscribers may have their copies bound for 2s. if sent to our Office, or, if accompanied by a cloth case, lor 6d. A few conies of Vols I. II. and III. can still be had. Vol. V. commenced on Januarv 4, isoz, and will bo complete in 16 numbers.

American Journal of Pharmacy -We have regularly forwarded our exchange copy and much regret that it lias not arrived Enquiries shall at once be made en tho subject Far from declining to cxe lanire there are few peiiodicals which wo receive with so much pleasure a* our Transatlantic contemporary.

F. (T. Joy.— The matter has been referred to our publisher, who will Attend to it.

J. Hartley. —The controversy had bettor ceaso.

Subscriber.—Wo believe the process to bo impracticable. If not it would, however, be terribly expensive.'

Erratum.— Pago 52, lino 7, from bottom,/or "chloroform" read "chlonue.

THE CHEMICAL NEWS.

Vol. V. No. 114.—February 8, 1862.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

On the Nascent Oxygen Tests for Aniline, by H. Letheby, M.B., M.A., Ph.D., SfC, Professor of Chemistry and Toxicology in the London Hospital College.

In the course of the last twelve months I have had to investigate, on hehalf of the Coroner, two cases of accidental poisoning by nitro-benzole; and finding that this compound was changed in the animal body into aniline, my attention was directed to the most delicate means for discovering the presence of that alkali. At a future time 1 will seek an opportunity of describing the process for extracting the aniline from the stomach, tissues, and urine; but having procured it, I found that nascent oxygen, from whatever source it was obtained, gave to aniline a rich blue, violet, or red colour, according to the proportion of oxygen acting and the strength of the acid solution containing the alkali. The best means of applying the test is by the agenoy of the galvanic battery. If a single drop, or even half a drop, of a solution of 1 part of aniline in iooo of dilute sulphuric acid (1 of acid to 7 of water) is placed on a clean piece of platinum, and touched with the negative pole of the galvanic battery (a single cell of Groves'arrangement) while the positive pole is in contact with the platinum, the liquid acquires a bluish, then a violet, and finally a pink colour. If the sulphatic solution of aniline is stronger, or the drop is concentrated on the platinum foil by evaporation, the colour is of a deeper blue, and by using the T^th of a grain of aniline with a drop of dilute sulphuric acid, consisting of equal ports of acid and water, the galvanic test gives a rich blue or purple blue reaction of considerable intensity.

This result is very much like that which I have described as tho galvanic test for strychnia,1 but the two alkaloids are distinguished, not merely by the volatility of aniline and its appearing in a medico-legal inquiry in the distillate from the suspected matters, but also by the circumstance that while strychnia requires the concentrated acid to show its violet colouration on platinum, aniline is best seen with the dilute acid.

Other sources of nascent oxygen may likewise be made available as a means of discovering the presence of aniline, but they are not all equally sensitive. The nL"1 °f a grain of aniline in half a drop of dilute sulphuric acid (1 to 1) on a white plate will gradually become blue if it be treated with a little peroxide of lead or red prussiato of potash; but it requires twice this quantity of aniline to show the tint with peroxide of manganese or bichromate of potash, and still more is required to produce a marked and decisive blue or purple reaction with peroxide of hydrogen, or peroxide of

1 m law*, June *8, i8j6, p, 708, iw4 Chmvitf. X(wi, vol. tt., p. j.

barium and sulphuric acid, or a solution of chlorine or chloride of lime.

This, however, is the general fact, that nascent oxygen from any source may be made the means of discovering the presence of aniline by the blue or violet colour which it imparts to the alkali, and that of all these sources of oxygen that from the positive pole of a galvanic battery is the most sensitive and the most manageable.

Finally, I may observe that these results from galvanic oxygen indicate the rationale of the action of many of the substances which have lately been patented for the production of aniline blues, purples, and reds; and by operating on a salt of aniline in dilute sulphuric acid in a porous cell, so as to prevent the nascent hydrogen from the negative pole of the battery influencing the effeot produced by the oxygen at the positive pole jvery brilliant effects may be obtained.

On the Analysis of Mixtures of Potash and Soda in Neutral and Alkaline Solutions, by M. Mohr.

This method is based upon the conversion of the potash into cream of tartar, and the estimation of the cream of tartar by a standard alkaline solution.

When the potash is in the state of carbonate, the operation is as follows:—The weighed potash is dissolved and saturated with powdered tartaric acid taken from a vessel which has been weighed beforehand. When the solution is saturated, there is added ro it as much more tartaric acid as has been used: a slight excess of tartaric acid is of no consequence, the solubility of bitartrate of potash in tartaric acid not being very great. This solution is evaporated to dryness on a water-bath, and the residue extracted with a saturated alcoholic solution of cream of tartar. This is thrown upon a filter, washed with the same alcoholic solution, and then estimated.

When the potash is in the form of a neutral salt, tartaric acid cannot be used, since this acid sets the mineral acids at liberty in which the bitartrate is partially dissolved; it must, therefore, be contrived that the mineral acids remain combined. All neutral salts of potassium ore changed on contact with bitartrate of soda into bitartrate of potash and a soluble soda salt. The solution is concentrated and evaporated to dryness; the residue extracted with alcohol saturated with bitartrate of potash placed upon a filter, and washed as before.

The difficulty consists in seizing the exact moment when there is sufficient bitartrate of soda added to decompose the potash salts. It is, however, easy to arrive at this in the following manner: —Standardize 10 o.e. of the alcoholic solution of cream of tartar; these 10 c.c. ordinarily require from 5 to 7 drops of normal soda solution. As the bitartrate of soda is soluble in tho alcoholic liquid, a sufficient quantity of this salt should be added so long as the acidity of the liquid increases, that is to say, so long as it requires to saturate the 10 c.c.

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of alcoholic liquid, more of the normal soda solution than would previously have been required before the employment of the alcoholic liquid. When the Io c.c. require 20 to 30 drops of normal soda solution, it may be filtered, washed, and estimated as before, taking care to continue tho washings until the strength of the alcoholic solution has returned to its original standard.

As in all methods of analysis by standard solutions, a certain amount of skill is required to arrive at accurate results.; but this plan seems to be capable of extreme accuracy, as the following experiments will show :—

One gramme of chloride of potassium was dissolved and treated with bitartrate of soda:

Potash found . . . 0-6312 grammes. Potash calculated . . 0-6320 „ In two grammes of the same substance there were obtained:

Potash found . . . 1-2625 grammes. Potash calculated -. . 1-2640 „ One gramme of sulphate of potash treated in tho same manner gave a result of l-olo grammes.

It is true that a portion of the alcoholic solution remains in the filter-paper; but, according to an experiment of the author's, on a paper of 115 millimetres, he found that it retained at most only one-sixth of solution.

This method may also bo applied to the estimation of potash by weighing. It is only necessary to precipitate the potash with chloride of platinum, and to weigh the resulting chloroplatinatc as in the ordinary process. There is an advantage in this pian, in being able to precipitate the potash by chloride of platinum, not only when it is in the state of chlorate, but also when it is present in the form of sulphate.

To estimate the potash in acid solutions, recourse must be had to the formation of alum, or to the following method recently proposed by M. Maumene.—Annalen tier Chemie und Pharmacie, cxix, I23.

On the Analysis of Mixtures of Potash and Soda, by M. Maumene. TrtE estimation of potash in tho presence of soda is effected by means of a salt of alumina; the alum is collected, and from the weight of this the amount of potash is calculated. Analyses made by this means give an approximate result which generally suffice for industrial operations. M. Balard has largely used it for his work on the constitution of the saline mother-liquors.

According to M. Maumene, the double sulphate of potash and copper

CuO.S03,KO.SO.,,6HO can be used, like alum, to condense the potashin an alkaline mixture.

The bases are converted into neutral sulphates, the mixed salts dissolved, the sulphate of copper is added, and the mixture left to evaporate spontaneously. Fifteen days arc required for the crystalline deposit to be complete; it is then washed, dried in the air, and weighed.

M. Barreswil remarks upon this [Repertoire de Chimie, i86t,p. 367) that this enormous time might undoubtedly be considerably abridged by precipitating the salt with alcohol, by effecting its crystallisation in concentrated liquids, or by many other plans.

On some Niiphthalic Derivatives, by M. L. DuSART. Some years ago I showed how potash-lime might be employed as au oxidising ageut when the object is to

fix oxygen on an organic matter without greatly altering the molecule. Thus I have been able, by theaction of this reagent, to produce phenoie acid (Itunge's rosolic acid) at will, by heating phenic acid in contact with the air, and at a fixed temperature.

P»y applying this process, on this occasion not to a body having a certain chemical affinity, l>ut to an agent entirely dissimilar—nitronaphthalinc,—I have obtained a new product, which appears to mo from its composition to be as interesting from its derivatives as from tho uses to which it may be susceptible. Monouitrated naphthaline, like naphthaline, offers great resistance to ordinary oxidising agents. Under the influence of such reagents, a portion of the substance is generally destroyed, without the formation of any new product; sometimes the molecular group is altered by the elimination of a certain quantity of carbon, and the naphthalic type disappears. Direct oxidation, simply fixing the oxygon, has not yet been effected. However, it may easily be produced, at not very high temperature, by the above-mentioned reagents, the energy of which is relatively very feeble.

To this end I mix one part of nitronaphthalinc, one part of caustic potass, dissolved in as little water as possible, and two parts of slaked lime; if too much water has not been added to tho potass, the mass is pulverulent. I introduce it into a tubulated retort heated in an oil-bath to a mean temperature of 1400, and pass into it a slow current of oxygen or of atmospheric air. The gas is slowly absorbed, the mixture takes a yellow colour, which deepens as the operation proceeds. In about ten or twelve hours the oxidation is complete, and almost all the nitronaphthnline oxidised.

I am persuaded that the presence of air or oxygen is indispensable to the reaction. 1 have failed to produce oxidation by replacing the potash with soda; the lime also appears to be of especial service, for an inert matter, sand, for instance, cannot be substituted for it.

Taken from the retort, the mixture yields to water a salt of potash of a reddish yellow colour, possessing considerable colouring power. Acids added in slight excess to the solution change it into a thick magma formed of a beautiful yellow body, which, on being washed in distilled water, becomes almost perfectly pure.

This new body, which I will call nitroxynaphthalic acid, preserves, when dry, all its brightness. Its taste, at first fresh, becomes bitter; it is inodorous, but in a pulverulent state it excites the nasal mucous membrane. It melts towards 100, and is not volatile; it dissolves in ordinary water, alcohol, pyroligneous acid, and acetic acid. In the latter it crystallises, by cooling, into beautiful golden-yellow needles.

It acts as a fceblo acid, and, with alkalies, forms deeply-coloured, very soluble, and crystallisable salts, which yield, by double decomposition with metallic salts, variously coloured prccipitatcj. Combined with bisulphite ofsoda.it forms a colourless salt, crystallising in fine needles; nitric acid attacks it with energy, forms oxalic acid, and at the same time a reddish resin, which by prolonged action is transformed into phthalic acid.

Contact with sulphuric acid heats it, developing sulphurous acid.

Energetic reducing agents transform it into a new substance, oxinaphthylamine.

The analysis of nitroxynaphthuline acid purified by cr3"sta11isation, and the estimation of its salts of baryta, lead, and copper, have led mo to represent it hy'the following formula: —

C,0H: (NOJ O.NO,

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