The ore is finely pulverised and roasted, first by itself and then once or twice with charcoal or coke, to remove sulphur, arsenic, and antimony. The residue is then digested for a quarter or half an hour with hot hydrochloric acid, and afterwards well washed with hot water. Iron, manganese, and copper, he states, are more completely removed by fusion with bisulphate of potash, and then treating with hydrochloric acid, and washing with water. Tungstic acid, if present, will now be removed by digesting with caustic potash or ammonia.

The oxide of tin, silica, &c., remaining is now mixed in a crucible with an equal weight of peroxide of copper, and two or three parts of flux, consisting of two parts anhydrous carbonate of soda, one part white flour, and a quarter part borax glass. The whole is then covered with a layer of common salt, upon which a piece of charcoal is laid. The crucible is then heated first to a red and then to a dull white heat for an hour, after which a button containing the whole of the tin and copper reduced will be found at the bottom.

As pure peroxide of copper may not be obtainable, the

author recommends that a portion of every sample should be separately assayed. The weight of the tin will be found by subtracting the weight of the copper from that

of the button.

On the Estimation of Copper and the Assay of Impure Commercial Cyanides of Potassium,

by M. FLAJOLOT.

THIS process is founded on the property possessed by cyanide of potassium of decolourising the ammoniacal solution of oxide of copper. The decolouration takes place with great precision, and as no precipitate is formed in the liquid it is very easy to ascertain the moment at which it is complete. The numerous experiments I have made with previously weighed quantities of copper have always given remarkably precise results, which I was far from expecting in the earlier experiments. In operating on a solution the volume of which did not exceed 200 cube centimetres, the error does not exceed two milligrammes, a degree of precision unattainable even by precipitating oxide of copper by potash. But to render the process applicable there must be in solution with the copper none of the metals forming cyanides soluble in ammonia, especially zinc, cobalt, and nickel.

In assaying complex ores like grey coppers, or those which have blende or nickeliferous pyrites for gangue, the copper must first be separated from the other metals. This is easily done by precipitating copper in the state of sulphide by hyposulphite of soda, as I have indicated in the Annales des Mines, fourth series, vol. iii. p. 641.

* Berg und Hutten, Zeitsch, 3, 1864, and Mining and Smelting Mag.,

April, 1864.

VOL. IX. No. 229.-APRIL 23, 1864,

In this kind of analysis I proceed in the following manner-Let us take grey copper mixed with blende, galena, or all the gangues which may accompany

copper ore.

Attack the finely pulverised ore by a mixture of nitric and sulphuric acids in a porcelain capsule, covered by an inverted funnel to avoid projections, and evaporate until the whole of the nitric acid is expelled; then add water and evaporate if necessary; then pour into the boiling solution hyposulphite of soda until the dark tint which at first occurs disappears. The precipitation is known to be complete when the sulphide of copper collects in flakes, floating in a milky liquid. Collect on a filter the sulphide (which will not contain the least trace of iron, zinc, cobalt, nickel, or even lead, but which may contain a little arsenic and antimony), and wash it very rapidly with hot water to prevent oxidation in the air.

Re-dissolve the sulphide in aqua regia, not heeding the antimony and arsenic it may contain, for they do not affect the following reaction. Supersaturate the liquid with ammonia, and pour into it until the colour goes a standard solution of eyanide of potassium, which gives the quantity of copper. The temperature of the cupric solution should not be too high, for less cyanide is required at the boiling point than when cold; up to 40° C. no inconvenience is experienced. Sufficient cyanide of potassium has been added when the blue colour of the liquid gives place to a very faint rose tint.

I use a solution of 15 grammes of cyanide in 50 grammes of water, and determine the standard by dissolving a given quantity of pure copper, say five decito describe. Since the solution of cyanide of potassium grammes, adding ammonia, and operating as I am about rapidly alters, it should be estimated before each assay.

Ammonide of copper becomes completely decolourisd when there are two equivalents of cyanide of potassium for one of copper, which corresponds to 4:12 grm. of cyanide to one gramme of copper.

of

If, then, on the one hand, we dissolve 1.12 grm, of cyanide of potassium or testing assay in a little water, and, on the other hand, prepare a solution of ammonide copper containing one gramme of metal and filling 100 divisions of a graduated burette, and then pour the second solution into the first, until a blue colour begins to appear, it is evident that the number of divisions necessary to produce this result will give in centièmes the richness of cyanide assayed, for the salts mingled with it exert no decolourising influence on the ammonide of copper.

But the operation is easier, the reaction more distinct, by proceeding inversely. For instance, dissolve one gramme of copper in a little nitric acid and add excess of ammonia. Dissolve 8:24 gr. of the cyanide to be tested, so as to have a volume of 200 cubic centimetres, then add this liquid to the first until the colour disappears. It is evident if 22 cubic centimetres are required, the richness of the cyanide is 100. Now that so much cyanide of potassium is manufactured for commercial purposes, so simple and easy a process may prove useful.-Moniteur Scientifique, v., p. 78.

American Adulteration.—A parcel of opium, some of which consisted of cakes evidently unbroken, was lately delivered to a laboratory in Philadelphia; one of the cakes, previous to being prepared for drying, was broken, and found to contain sixteen leaden bullets, weighing 74 oz., evidently incorporated for increasing the weight.

TECHNICAL CHEMISTRY.

On a Means of Obtaining Bismuth, by M. BALARD. THE high price of bismuth for some years past has induced M. Balard to undertake the search for this metal in old type materials. When it was cheaper, bismuth entered into the composition of the alloy for printing purposes. M. Balard proposes to effect this industrial analysis in the following way :

1. Dissolve the material in nitric acid, so as to transform all the tin into metastannic acid, which isolate by filtration from the acid solution of nitrates of lead and bismuth; wash with acidulated water, dry and reduce by charcoal.

2. Into the liquid, neutralised as much as possible, plunge plates of lead, which precipitate all the bismuth in a metallic state; dry and melt with a reducing agent. 3. Precipitate the lead from the last liquid by carbonate of soda; separate, wash, dry and reduce with charcoal.

This way of operating gives the three metals in a metallic state; it may undergo several modifications for isolating the metals under another form according to the arrangement of the products. To obtain extremely pure subnitrate of bismuth, says M. Balard, it is necessary only to neutralise the liquid containing the soluble nitrates, and dilute with a large quantity of water naturally free from carbonates, chlorides, or sulphates. After again neutralising and diluting with water and repeating the operations several times, the greater part of this metal becomes isolated in the state of white bismuth.-Journal de Pharmacie et de Chemie, xlv. 160.

Extraction of Auriferous' Silver from its Ores,
by M. J. NICKLES.

THOUGH the treatment of argentiferous ores is easy, and that of auriferous ores not very complicated, it is other wise when the two metals are associated, for then the properties of the one prevent the manifestation of the properties of the other. If, for instance, auriferous silver is treated by chlorine water, the core immediately becomes covered with a coating of chloride of silver, which protects the rest from the action of the solvent. If this is attacked by salt water, ammonia, or hyposulphite of soda, the core becomes unmanageable, the chloride of silver dissolves, it is true, but leaves behind it a layer of metallic gold which in its turn resists the action of the solvents of chloride of silver.

After many tentative trials the simple plan occurred to the author of associating the two solvents, chlorine and chloride of sodium. He took salt water concentrated and saturated with chlorine, and digested the auriferous alloy in it. By burning an ore of this kind and then washing it with the above solvent, the chlorine attacks the metallic particles, and then transforms them into chloride, which is dissolved by the sea salt.

It is thought that this solvent may serve for the treatment of ores so poor in metals as to be discarded for the ordinary extracting processes.-Polyt. Notizblatt, vol. xviii. p. 286.

Royal_Institution.-Tuesday, April 26, at three, Professor Blackie, "On Homer." Thursday, April 28, at three, Professor Blackie, "On Homer." Friday, April 29, at eight, Professor Williamson, "On the Existence of Atoms." Saturday, April 30, at three, Professor Frankland, "On the Metallic Elements."

PHYSICAL SCIENCE.

Spectrum Analysis.-New Researches, by MM. MITSCHERLICH, BOETTGER, PLUCKER, and HITTORF. A resumé of the many interesting researches on spectrum analysis made since its discovery may now be of interest. While examining a substance containing baryta, M. Mitscherlich observed two brilliant green rays, seeming to indicate the presence of a new metal. When he introduced into the flame a drop of a solution of chloride of barium mixed with sal ammoniac, he found that these rays appeared either singly or accompanied by those of barium. These same rays took the place of the ordinary barium spectrum, when, above the supporter of a salt of baryta, he placed a bundle of platinum wire impregnated with hydrochloric acid. M. Mitscherlich obtained invariable spectra during several hours by a particular arrangement pointed out in his memoir.

Chlorides of strontium and calcium give spectra very different from those of strontium and calcium, although these new spectra are rarely unaccompanied by those of the metals.

Chlorides of earthy alkaline metals give spectra very unlike the spectra of the metals themselves. The iodides, sulphides, and fluorides of these metals yield no spectra, or, rather, they give those of the metals which are reduced by the carbon and hydrogen of the flame. The spectra of metallic copper, of chloride, and iodide of copper present essential differences. Sulphide of copper gives no spectrum.

Chloride of potassium mixed with sal ammoniac gives no spectrum. Chloride of sodium, under the same circumstances, shows only the yellow sodium ray. On introducing a bundle of platinum wires, steeped in hydrochloric acid, into a flame giving potassium rays, these rays immediately disappear.

Chlorides of potassium and sodium have no proper spectrum. The result of these experiments is, that metals do not, as is usually supposed, always give the same spectrum, whatever may be the combinations in which they are found.

M. Mitscherlich has proved by the following experiment that it is the metal itself reduced in the flame which produces the spectrum. He introduced some caustic soda into a porcelain tube, heated it to redness, and on examining by the spectroscope the light traversed by the vapours and that emitted by them, found that neither of them showed the sodium line; but on examining the vapours of metallic sodium, under the same conditions, found a brilliant sodium ray.

M. Boettger observed† that selenium and selenide of mercury gave a spectrum, in which he remarked, from yellow to extreme violet, a great many equidistant dark

rays.

Col gas, after passing through a flask containing chloroform, burns with a green flame, which, analysed by the spectrometric apparatus, shows two blue rays close together, three large green rays comprised between Fraunhofer's rays D and C, and a large blue ray situated between the rays F and G.

Borax gives three or four green rays; protochloride of manganese, four green, and one large orange ray; chloride of bismuth gives numerous brilliant red and blue rays, which rapidly disappear; and chloride of lead gives a number of rays distributed over the entire spectrum.

*Bulletin de la Société Chimique. Bulletin de la Société Chimique.

M. Erdmann remarked that lime showed a blue ray close to the ray 8 of rubidium, which might prove a source of error to chemists. According to Dr. Gladstone, didymium may be known by two black rays, one near the ray D, the other between E and C. If the solution of didymium is from eight to ten centimetres thick, seven black rays of various sizes will be visible. MM. Plucker and Hittorf, I in recent experiments. proved that certain bodies, such as nitrogen and sulphur, do not give a unique spectrum, but, according to the temperature to which the incandescent vapour is submitted, two very different spectra. To ascertain this, they passed through the tubes, containing gas or vapour at a pressure of a few centimetres, first the ordinary current of Ruhmkorff's induction coil, then the same current with its calorific action increased by the interposition of a Leyden jar. By varying the surface of the jar, and thus gradually raising the temperature of the gaseous body, they found that the transition from one spectrum to another was suddenly accomplished. Thus an essential modification must evidently have taken place in the molecular constitution of the body; but with the lowering of the temperature the difference disappeared.

The spectrum corresponding to the lowest temperature, and which MM. Plucker and Hittorf name the first spectrum, is formed of large bands more or less regular, oftener presenting the appearance of channelled spaces cut by black rays. The second spectrum, corresponding to the higher temperature, has brilliant rays on a more or less luminous ground. The brightness changes from one ray to another, quite irregularly.

Sulphur furnishes a striking experiment, showing the abrupt passage from one of the two rays to the other. At the moment the first spectrum attains its maximum of brightness, it suddenly disappears, and gives place to the second spectrum, the richest in brilliant rays which the authors have ever seen. On lowering the temperature the second spectrum disappears and the first reappears.

Oxygen, chlorine, bromine, iodine, &c., have one spectrum only.

To render more precise this entirely new fact, of two absolutely distinct spectra belonging to one simple body, MM. Plucker and Hittorf have studied the spectra of compound gaseous bodies. They have ascertained by spectrum analysis that none of the bodies examined by them resist decomposition by means of the heat from an induction current. Dissociation always took place; the tubes and the molecules of the various simple substances which constitute the compound gaseous body remain under conditions the most favourable to recomposition, as soon as the extreme elevation of the temperature no longer opposes it. It may then be affirmed that there is no such thing as a spectrum of a compound body. Thus, oxide of carbon, carbonic acid, olefiant gas, &c., decompose, and give the spectrum of carbon vapour, one of the most beautiful and curious to behold.

According to MM. Plucker and Hittorf, nitrogen has three spectra, or three different molecular conditions. In the two first conditions nitrogen gives two distinct first spectra, one of a yellow colour, corresponding to the less degree of incandescence; the other, to a higher degree of incandescence, of a blue colour. In the third molecular state, produced by a much more intense state of incandescence, the second spectrum appears.-Journal de Pharmacie et de Chemie, xliii., 442.

Les Mondes.

PHOTOGRAPHY.

Preparation of Alkaline Bromides, by M. KLEIN. BROMIDES of metals of the first section being most used in photography, the author has endeavoured to find a way of preparing them more expeditious than those generally adopted, and it occurred to him to apply a process M. Liebig employs for producing alkaline iodides.

Bromide of Calcium.-Mix one part of finely powdered amorphous phosphorus with thirty or forty parts of water in a capsule placed under the basketfunnel, and gradually add 12'5 parts of bromine. The mixture is effected with disengagement of light, and the liquid becomes heated; then shake it and add the bromine until the mixture begins to decolourise. When all the bromine has been used, heat in a sand bath; and when all the colour has disappeared, add sufficient bromated water to impart a yellow tinge to the solution. Then decant immediately, and neutralise by a slight excess of lime. Filter, wash, and evaporate. The excess of lime carbonates in the meanwhile, which necessitates a second filtration, after which evaporation in a water bath completes the operation.

With 16 grains of amorphous phosphorus, 200 grains of bromine, and about 75 grains of quicklime, the author obtained 230 grains of bromide of calcium. Bromides of barium and strontium may be prepared in the same way.

Bromide of Magnesium.—Neutralise with magnesia the acid liquid obtained by attacking part of phosphorus by 125 parts of bromine in presence of water. After filtering, evaporate in a water bath and dry over sulphuric acid.

To Obtain Bromide of Lithium.

Decompose bromide of calcium by carbonate of lithia used at first in insufficient quantities. Leave to digest for twentyfour hours, after which finish the precipitation by carbonate of lithia.

Bromides of potassium and sodium the author obtains by a process previously described for iodides (Journal de Pharmacie et de Chemie, xli. 520), that is to say, by the decomposition of bromide of calcium by means of sulphate of potash or soda.-Journal de Pharmacie et de Chemie,

xlv. 111. 64.

PROCEEDINGS OF SOCIETIES.

ROYAL INSTITUTION OF GREAT BRITAIN. WEEKLY EVENING MEETING.

Friday, February 12, 1864.

at high temperatures they combine, it is true, but yield comparatively very few compounds.

It was long after chemists had effected the analysis of organic bodies before they learnt how to effect the synthesis of even one of them, and hence the belief sprung up that organic products, such as those on our tray, were intrinsically different from mineral products. Whilst stones,

President, in the Chair.

On the Synthesis of Organic Bodies.

By J. ALFRED WANKLYN, Esq., Professor of Chemistry, London Institution.

On this tray you will see a collection of well-known sub. stances.* Compare these substances with one another, and you will be struck with their dissimilarities. Some are solids and crystalline and brittle; others are liquids which are more fluid than water. Some are without colours; others are highly coloured, and are used for dyeing. Some are sweet, others are bitter; some have delightful perfumes, others have dreadful smells; some are wholesome food, others the most powerful poisons

known to man.

In spite of this wonderful diversity in their properties, all the specimens on this tray are compounds of carbon, with a very few elements. Carbon, hydrogen, oxygen, and nitrogen are the only elements which occur in this collection of substances. Some of these substances contain carbon and hydrogen; some contain carbon, hydrogen, and oxygen; some carbon, hydrogen, and nitrogen; and some again contain carbon, hydrogen, oxygen, and nitrogen. But not one of the specimens on this tray contains anything besides these four elements.

There is no difficulty in resolving any one of these substances into its ultimate elements. This sugar,† for example, on being heated to redness in a tube, leaves a black deposit, which is carbon, whilst a liquid, which is water, distils over. If we were to electrolyse this liquid, we should obtain hydrogen and oxygen, and so we should exhibit carbon, hydrogen, and oxygen obtained from sugar. Again, instead of heating this sugar in the tube without allowing the air free access to it, we might burn it in excess of oxygen. If we were to do so, we should obtain carbonic acid and water, and, moreover, all the carbon in the sugar would assume the form of carbonic acid, and all the hydrogen the form of water. So we can obtain carbon and hydrogen, either in the free state, or in the very common and well-known forms of combination as carbon acid and water. Nitrogen, when it is present, can be made to assume the form of free nitrogen. For that purpose, all that is requisite is to heat the substance to redness with excess of oxygen, and to adopt certain precautions to avoid the production of oxide of nitrogen.

Thus, the pulling to pieces of these substances on the tray is a matter of very little difficulty: more than fifty years ago chemists could do that; but how to put the pieces together again is a much more difficult task.

Sugar consists of seventy-two parts by weight of carbon, eleven parts of hydrogen, and eighty-eight parts of oxygen. We may bring together carbon, hydrogen, and oxygen in these proportione, and shake them up together, or heat them or cool them, and yet we shall never get them to combine so as to form sugar. Alcohol consists of twentyfour parts of carbon, six parts of hydrogen, and sixteen parts of oxygen, but no alcohol ever results from making such a mixture. Neither sugar nor alcohol can exist at the temperature to which it is requisite to raise our mixture of carbon, hydrogen, and oxygen, in order to get chemical action to set in. At ordinary temperature the organic elements will not enter into combination, whilst

* A tray, with a number of organic bodies lying upon it, was before the speaker.

↑ Cue sugar was heated to redness in a tube.

particles held together by mere dead forces, sugar, alcohol, &c., were regarded as being held together by vital forces, as being, in short, in some subordinate way, alive.

Now, no more positive refutation of this notion can be imagined than the artificial construction of substances, in every respect, like those obtained from the animal and vegetable kingdoms; and hence some of the philosophical interest attached to the problem which forms the subject of this discourse.

The first definite example of the construction of an organic body from inorganic materials was given by Wöhler in 1828, when he made the organic base urea from cyanate of ammonia.

Let us trace the steps of this process. Cyanide of potassium-a body which can exist at a red heat (some cyanide of potassium was exhibited in the form of tabular masses which had been fused), and which can, moreover, be formed directly from its constituents (carbon, nitrogen, and potassium)-was oxydised by means of peroxide of manganese at a low red heat, and so cyanate of potash was obtained. The cyanate of potash was next converted into cyanate of ammonia by double decomposition with sulphate of ammonia. Thus cyanate of ammonia was produced from its elements by a process which, although indirect, still did not involve the action of either a plant or an animal. Cyanate of ammonia becomes urea when its solution in water is simply evaporated to dryness.

structed should have been a nitrogenous compound. It was curious that the first organic body to be con

In 1831, three years after this important discovery of Wöhler's, formic acid-the first term of the fatty acid series-was obtained from inorganic materials by Pelouze. The process was this:-Hydrocyanic acid, a body capable of being obtained from inorganic materials, was heated either with strong alkalis or acids, and was so made to react upon the elements of water as follows:Hydrocyanic Acid. Formic Acid.

CNH+2H,O=NH ̧+CH2O2

and yielded formic acid.

It does not appear that this research of Pelouze's attracted that attention which it deserved. This we must attribute to the circumstance that at this period the position of formic acid in the organic series was not recognised.

The next step of importance in organic synthesis was taken by Kolbe in 1845. It was the synthesis of acetic acid, the second term of the fatty series. Kolbe's process was this:-Sulphide of carbon, obtained by the direct combination of carbon with sulphur at a red heat, was submitted to the action of chlorine at a red heat, by which means certain compounds of carbon and chlorine were obtained. One of the compounds, C2Cl, was then acted upon by chlorine in the presence of water, and tri-chloracetic acid resulted.

Having thus got tri-chlor-acetic acid by thoroughly inorganic means, Kolbe availed himself of the observation

which had been made of Melsens, that treatment of trichlor-acetic acid with potassium-amalgam and water converted it into acetic acid.

Kolbe was fully sensible of the scope and importance of his discovery. The following passage occurs in his paper, published in Liebig's Annalen for 1845:-" From the foregoing observations we deduce the interesting fact that acetic acid, hitherto known only as a product of the oxidation of organic materials, can be built up by almost

direct synthesis from its elements. Sulphide of carbon, chloride of carbon, and chlorine are the agents which, along with water, accomplish the transformation of carbon into acetic acid. If we could only transform acetic acid into alcohol, and out of the latter could obtain sugar and starch, then we should be enabled to build up these common vegetable principles by the so-called artificial method from their most ultimate elements." Thus it appears that Kolbe looked forward to the building up of organic bodies in general, and that he was quite alive to the fact that the synthesis of acetic acid completed the synthesis of the derivations of acetic acid.

Among these derivations may be enumerated acetone, the product of the destructive distillation of acetates; marsh gas obtained by distilling an acetate with a caustic alkali; ethylene, obtained by Bunsen by heating kakodyl, which itself results by the action of arsenious acid upon an acetate. The electrolysis of acetic acid, which Kolbe accomplished a few years afterwards, yielded methyl and oxide of methyl, which latter in its turn could be transformed into any other methylic compound.

Marsh gas was, moreover, prepared by Regnault by treating CC, with nascent hydrogen; and the common methylic compounds appear to have been produced by Dumas from marsh gas, the chloride of methyl having been obtained by Dumas, by the action of chlorine upon marsh gas.

Before 1854, all the foregoing synthesis were fully completed, i.e., there was no step missing between the elements themselves and the most complex compound reached; but, in addition to these complete and definite syntheses, there had also been a good deal of building up of an incomplete or of a less definite character before 1854.

It was known, in a general way, that organic bodies of tolerably simple composition sometimes gave complex products on destructive distillation. Thus, alcohol was known to give naphthaline, benzol, and carbonic acid when it was pressed through a red-hot tube. Formiates were also known to yield hydro-carbons when they were subjected to destructive distillation. The precise dates of these different observations I cannot give, but hand-books of chemistry published before 1854 contain a statement of

the facts.

A few years after 1820, before Wöhler's celebrated Synthesis of Urea, a very remarkable instance of passage from a simpler to a more complex compound was given by Faraday and Hennell. This example is placed along with the indefinite syntheses because it was generally disbelieved in by chemists, and only within the last few years, when it was confirmed by Berthelot, received the general assent. Faraday and Hennel found that olefiant gas was absorbed by sulphuric acid and gave sulpho-vinic acid, from which, of course, alcohol and the ethers might be procured. Liebig denied what Faraday and Hennell had asserted, and the latter did not insist upon the correctness of their work, and did not take the necessary steps for ensuring the reception of their results.

Shortly before 1854 a most capital addition to the art of organic synthesis was borrowed from the doctrine of the homologous series. I will endeavour to explain it.

Organic bodies repeat themselves: thus common alcohol has a whole series of representatives, differing from it in formula by n (CH), but resembling it very closely in chemical functions. Alcohol and these its representatives constitute a homologous series. Every one of these representatives (homologues) of alcohol possesses a set of ethers and other derivatives, just as common alcohol possesses its ethers and derivatives. With certain limitations, it is true that whatever reaction can be accomplished with one alcohol can be accomplished with any other alcohol of the

The effect of the alkali is to cause decomposition of water by means of the cyanide, and the reaction very closely resembles Pelouze's, of which mention has already been made.

By means of this synthesis, which is general to the whole series, chemists acquired a method of ascending from any given alcohol to the acid belonging to next higher alcohol. It will be evident, however, that this step, important though it was, did not suffice to enable chemists to march regularly up the ladder. The step from acetic acid to alcohol-from an acid to an alcohol of the same carbon-condensation-was wanting.

This synthesis by series was an incomplete synthesis; there was a gap requiring to be filled up, in order that the regular march might be made up the vinic series.

From the foregoing, it will be seen that by the year 1854 very considerable progress had been made in the building-up of organic bodies from their ultimate elements. We now pass on to the consideration of the period comprising the last ten years, from 1854 up to the present time.

During this period we have had new methods of accomplishing some of the syntheses which had been effected previously. Thus, formic acid, which, as we have seen, had been formed from inorganic materials so long ago as 1831, was built up by Berthelot by means of carbonic oxide and caustic potash,-

CO+ KHO = CHKO2 and again by Kolbe, by using carbonic acid, moisture, and sodium (the moisture and sodium giving nascent hydrogen), CO2+H+Na = CHNAO2.

Again, also, the passage from an alcohol to the next higher acid was repeated. Carbonic acid and a compound of an alcohol radicle with an alkali metal coalesced, and formed a salt of a fatty acid, thus:

:

Sodium-ethyl. Propionate of Soda. CO2+ NaC2H ̧ CH,NaO2.‡

=

Still these reactions, however interesting they might be, were not new syntheses; they were only new methods of effecting old syntheses.

The great problem, how to step from one alcohol to that next above it, has received a general solution from Mendius. Mendius used cyanogen compounds, those hydrocyanic ethers which had already done such good service to organic synthesis, and exposed them to the

took place on bringing carbonic acid into contact with sodium-etbyl The experiment was shown, and the great evolution of heat which was apparent.