L.

OERTLING,

MANUFACTURER OF BALANCES.

Assistant Chemist for Cement Works. - The

vacancy advertised in our issue of May 30, "Cement," has been filled, and the Advertisers wish to acknowledge with thanks the applications they have received.

Royal Mint, India and Colonial Offices); the National Physical Labora tory; the Bank of England; Standards Bureau, Washington; &c. Chemical Balance. No. 6 SB,

wanted to assist in Works Investigations. Give full particulars of training. State age and salary required.-Address, O. T., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C.

The Owners of BRITISH PATENT No.

18342 of 1909, entitled "Improved Process of Manufacture of Viscous Spinning Solutions of Cellulose," are desirous of disposing of the Patent or entering into working arrangements, under licence or otherwise, with firms likely to be interested in the same.

A copy of the Patent Specification and full particulars can be obtained from and offers made (for transmission to the owners) to MARKS and CLERK, 57 and 58, Lincoln's Inn Fields, London, W.C.

The Proprietor of the BRITISH PATENT

No. 17263/10, relating to "Process for the Destruction of Hairs, Horsehairs, Finger Nails, and Horny, Gelatinous, and the like Substances contained in Floss and Waste Silk in general," is desirous of entering into arrangements, by way of Licence or otherwise, on reasonable terms, for the purpose of exploiting the same and ensuring its full development in this country.

All communications should be addressed to Mr. SEIGNOL, 32, Rue Servient, Lyons, France.

MANUFACTURING DEHYDRATED ZINC

SULPHIDE.

The Proprietor of PATENT No. 9391 of 1910,

relating to a "Method of Manufacturing Dehydrated Zinc Sulphide," desires to enter into negotiations with one or more firms in Great Britain for the grant of Licences to manufacture under Royalty. Enquiries to be addressed to Messrs. CARPMAEL and CO., 24, Southampton Buildings, London, W.C.

INSTRUCTION IN

PURE CULTIVATION OF YEAST.

Courses for beginners, as well as for Advanced Students in Physiology and Technology of Fermentations. Biological Analysis of Yeast. The Laboratory possesses a numerous collection of Yeasts (Brewers', Distillers', Wine, Disease Yeasts), Moulds, and Bacteria.

Manuals: ALFRED JÖRGENSEN, "Micro-organisms and Fermentaion," 4th edition (Charles Griffin and Co., London), and "The Practical Management of Pure Yeast" (London, "The Brewing Trade Review"). The Laboratory supplies for direct use Pure Cultures of Yeast for Breweries, Distilleries Wine Manufactories, &c., and performs Analyses of Yeasts, &c.

Further particulars on application to the Director-
ALFRED JÖRGENSEN, The Laboratory,
Copenhagen Y., Denmark.

ABSOLUTE ALCOHOL,

THE RECENT DEVELOPMENT OF NEUTRAL

SALT REACTIONS.

By M. FORT.

ALTHOUGH the law of mass action is now of fundamental importance in chemistry, it is frequently neglected or imperfectly appreciated in its bearing on technical and analytical problems, and perhaps is less rarely looked to for an explanation of such than the everyday "commonsense chemical notions which by constant use, as in routine work, often acquire high false values. Thus one readily thinks of caustic soda expelling ammonia from a salt in solution, but to think of ammonia expelling sodium as sodium hydrate from a sodium salt in solution creates some degree of mental confusion, greater or less according to one's actual familiarity with the potency of

mass law.

It became known among chemists (the writer is unaware of the original source) that sodium sulphate and acetic acid, under certain conditions, may react as though free sulphuric acid is actually present. The experiment may be shown with methyl orange as indicator and a hot dilute solution of acetic acid. On adding sodium sulphate a colour change, denoting an increase in acidity, takes place, ascribable to the liberation of a small amount of free sulphuric acid by the action of the weaker acetic acid competing for the base combined in the salt. This reaction was known as the "neutral salt reaction," and was little heard of until recent years. It is a direct outcome of mass law and demands expression by means of a reversible equation :

Na2SO4+2CH3COOH 2NaOOC CH3+H2SO4. The equilibrium is determined mainly thus ←, but it is never completed, hence the necessity for the presence of a small amount of free mineral acid, liberated by the weaker organic acid from the neutral salt in attaining equilibrium. As might be expected there is no need for the amount of free acetic to be large in order to get an appreciable amount of sulphuric acid formed, if the mass of sodium sulphate present be considerable. The reaction is favoured by rise in temperature, as this increases the extent of hydrolytic dissociation of the neutral salt, which dissociation is supposedly necessary before the neutral salt reaction can take place.

A further observation was made by L. L. Lloyd (Fourn. Soc. Chem. Indus., 1910, p. 1361), namely, that in a neutral salt reaction between formic acid and sodium sulphate, the presence of wool greatly increases the amount of sulphuric acid formed, in fact from a mere trace to a distinctly appreciable amount. Lloyd obtained some

of the free acid from the wool by extraction with water. This is the first indication of the recognition of the important influence exerted by neutral salt reactions in technical chemistry.

Quite apart apparently from this work is an observation of Arndt's (Zeit. Anorg. Chem., xxviii., 365), that by heating a strong solution of sodium sulphate with litmus an alkaline reaction is obtained. This was confirmed by Kraus (Farb. Zeit., 1911, p. 333), and applied by him to explain certain phenomena connected with the dyeing of wool, e.g., the deterioration of the wool fibre dyed in socalled neutral dye-baths with sodium sulphate as assistant. He could not, however, obtain similar alkalinity with sodium chloride, and Dreaper (Journ. Soc. Dyers and Co., 1911, p. 293) suggested that the difference lay in the inability of sodium chloride to react in a similar way to the following: Na2SO4 + H2O NaOH+NaHSO4. Later work has explained these observations in a more satisfactory way.

It appeared to the author that the known neutral salt reaction if correctly understood must have a counterpart in the reactions of weak bases with salts of stronger bases, and considerable evidence was acquired of such being the case (Fort, Fourn. Soc. Dyers, 1912, p. 314). In the first place Arndt's observation was confirmed, using also alizarin as indicator, and a series of salts classified on the basis of alkalinity or the absence of an alkaline reaction at the boil. Later it was shown by the author, after extending his knowledge of neutral salt reactions, that the supposed alkalinity of sodium sulphate at the boil is not due to special conditions of ionisation determined by rise in temperature, as was tentatively suggested by Procter (Fourn. Soc. Dyers, 1913, p. 40), but is part of a neutral salt reaction with the acidic indicator, e.g., in the case of alizarin a small quantity of coloured sodium alizarate is formed, and a similar explanation covers the reaction with litmus. On cooling the colour disappears, due to a reversal of the reaction. Since sodium chloride is the salt of a stronger acid than sodium sulphate it is not so readily hydrolysed and decomposed by alizarin, and hence shows no colour reaction at the boil. However, by using a more strongly acid indicator, for example di-nitro-anthrachrysonedi-sulphonic acid, a distinct alkaline colour reaction was obtained with sodium chloride at the boil. Further, it was shown that by using as indicator a drop or two of a dilute solution of rosaniline base carefully decolorised with very dilute caustic soda, on heating with a solution of sodium chloride or sulphate a pronounced magenta colour appeared, i.e., an acid reaction was given. In fact there is no evidence of the supposed alkalinity of sodium sulphate solution at the boil, apart from a neutral sait re.

action with the indicator used, which agrees with the apparently surprising fact that the same sample of sodium sulphate may be made to show either an acid or an alkaline colour reaction in hot solution according to whether the indicator be respectively basic or acid in character. In this type of reaction the presence of water is regarded as essential to give hydrolytic dissociation of the salt which is increased greatly as temperature rises, with the result that the free weak acid or base can compete for base or acid respectively as the case may be, formed from the salt by hydrolysis, thereby causing the formation of more or less of the free strong acid or base from the salt. The former phase of the reaction is seen in the colour indications obtained from sodium sulphate as described above. The latter phase of the neutral salt reaction, i.e., the liberation of varying small quantities of strong acids or bases by the interaction of solutions of their salts with weaker acids or bases, is of great technical interest.

A new neutral salt reaction was described by the author (1912, loc. cit.), who found that on adding sodium sulphate or chloride to a boiling aqueous solution of aniline in a platinum dish, containing alizarin as indicator, an alkaline colour reaction was obtained at once. This is assumed to be due to two reactions :

(i.) NaCl+H20NaOH + HCl.

Similar reactions were obtained with a variety of organic bases, and also one found it possible to show even the ability of ammonia to release caustic soda in a solution of a neutral sodium salt. Phenolphthalein was used as indicator, and as is well known it reacts feebly and incompletely with ammonia in dilute solution; in fact the pink colour obtained in the cold fades on warming, due presumably to increased hydrolysis of the rather unstable coloured compound as temperature rises. The same influence, however, promotes the neutral salt reaction, as was explained previously. If, then, a dilute solution of ammonia be taken of such a strength as to give a faint pink colour with phenolphthalein at the boil, on adding sodium sulphate or sodium chloride to the hot solution a much deeper pink is at once shown. The experiment may be varied by starting with two portions of cold dilute ammonia just strong enough to give a colour with phenolphthalein, to one portion sodium chloride being added before gently heating. The portion containing the neutral salt may be shown to remain pink up to the boil, while the other fades on warming through a few degrees. On cooling a similar shade is regained in each case.

The author has been led to believe also in another type of reaction, i.e., the double neutral salt reaction which must take place in solution, between any two neutral salts obtained from different acids and bases, resulting in the establishment of an equilibrium in which all four possible salts of these acids and bases are concerned. For example, it is found that neither calcium sulphate nor sodium chloride give a colour reaction when a solution is boiled with alizarin as indicator, the contrary being the case with sodium sulphate, as was mentioned. However, by adding sodium chloride to a boiling solution of calcium sulphate in a platinum dish, the crimson alkaline reaction with alizarin is obtained. This is explained as due to an equilibrium involving the formation of appreciable quantities of calcium chloride and sodium sulphate, sufficient to give the above colour reaction.

Technical and other Applications.

There has been rapid application of the knowledge of these reactions to industrial problems. Procter has applied it to the pickling of hides (Collegium, 1912, No. 512, p. 687), and has shown that N/10 formic acid along with common salt can fix in gelatin an amount of hydrochloric acid equal to that taken up from N/10 hydrochloric acid itself. L. L. Lloyd has also adequately

explained the formation and avoidance of salt stains on hides by means of neutral salt reactions (Collegium, 1913, No. 517, p. 188), and also the occurrence of tendered cotton threads in half wool unions after dyeing in a bath containing as assistants formic acid and Glauber's salt. This latter instance may be used to show how the knowledge recently acquired may solve very troublesome technical difficulties. It was well established and accepted that formic acid does not tender cotton, and it found favour with dyers largely on account of this great advantage which it possesses over sulphuric acid. It is a matter of equal faith that sodium sulphate alone causes no deterioration of the cotton fibre, and apparently no one saw any reason why danger should be apprehended when these assistants were used together; indeed, although occasional tendering of batches of goods occurred where it was most difficult to avoid the correct or something approaching the right conclusion, the "common-sense" view of the impossibility of a weak acid like formic setting free sulphuric acid, seems to have prevented its being reached. Lloyd showed that not only is sulphuric acid produced, but being absorbed by the wool present the reaction is much more considerable, and free sulphuric acid can be extracted from the fabric with water in appreciable amount. By a thorough rinsing after dyeing, troubles from this cause may be largely obviated.

The author has shown that wool itself can to some extent decompose even such stable salts as sodium sulphate in boiling baths, both the strongly basic and apparently weaker acid properties of the amphoteric fibresubstance being involved (Journ. Soc. Dyers, 1913, p. 80). The basic properties of wool are no doubt mainly responsible by causing the transference of sulphuric acid to the fibre, while the prevailing acidity of a portion of the wool or its hydrolysis products causes a part of the fibre to be dissolved away by the alkali constituent of the salt. This is the reason for the injury done to the lustre of wool when dyed in hot neutral baths containing Glauber's salt. which may be largely avoided by addition of glue to the dye bath. As may be well understood from what has been said, common salt is injurious to a less degree and is often preferred, e.g., by garment dyers, on that account. Further, it was shown that a certain degree of tendering of cotton in a half-wool union fabric may be caused by a hot bath of sodium sulphate in the following way:-The wool combines with sulphuric acid obtained from the salt, as already explained, and retains a portion firmly in spite of washing with water, which on drying and storing is partly set free, in which state it tenders the cotton fibres present (Journ. Soc. Dyers, 1913, p. 120).

Very recently Lloyd has explained to the Society of Dyers and Colourists (London Section) the causes of certain defects in silk fabrics. Silk is found to decompose to some extent mineral halides in solution, forming halogen compounds with the silk fibre, from which later the free halogen may be liberated and give rise to oxidation and deterioration of the fibre on keeping.

The recent legislation against filthy flock for upholstery purposes has set up a minimum chlorine content as a standard of purity, which, however, it is found may be approached by fresh clean wool (Fourn. Soc. Chem. Ind., 1913, p. 402), a discovery which, in the light of what has been said, may be accounted for by conditions on the live sheep, i.e., the presence of organic acids and mineral chlorides from perspiration. The ordinary perspiration test applied to dyed fabrics is a treatment with weak acetic acid, and has proved to be quite inadequate for practical conclusions to be drawn. The author has for some time replaced this test in his own laboratory by a test employing common salt in conjunction with acetic acid, and may now recommend it for use where the ideal one of actual wear is inapplicable. A similar modification for the purposes of an alkaline perspiration test might be arranged, e.g., for horse cloths.

The physiological interest attached to the neutral salt reactions is necessarily great, but at the present one may

CHEMICAL NEWS, July 4, 1913

not dogmatise much. However, it is clear à priori, for example, that organic acids of the stomach or fruit acids in presence of common salt or mineral chlorides taken with food, will set up an equilibrium in which free hydrochloric acid will play a part, and in which albuminoids also present can favour the production of this mineral acid (compare the effect of hide, wool, and silk substance in this connection), which being required for digestion of these same albuminoids, will be produced as required in complete accordance with beneficent natural law. In regard to the known secretion of hydrochloric acid from special glands, as distinct from its formation by reactions among the contents of the stomach, the amount of sodium chloride in the blood forming a permanent reserve may be looked to as the starting material, and a neutral salt reaction as the most likely chemical means to be employed. The author has not been afforded opportunity of an experimental justification of this view, as was originally intended, owing to a greater personal interest in the rapidly developing textile applications of the knowledge of neutral salt reactions. This knowledge has suggested an explanation of a root difficulty in the acceptance of the chemical theory of dyeing, namely, as to how a free colour acid, the dyeing of which on wool is greatly promoted by a previous treatment of the fibre with sulphuric acid, can effect combination with wool already combined with a strong acid. In the author's opinion the first part of the answer to this is that the partial hydrolysis of the wool by the acid causes a great increase in the available basic parts of wool, and secondly, that local conditions in or on the fibre favour a reaction offering great analogy with neutral salt reactions, for it is found that wool, after treatment with sulphuric acid and then with water till no more acid is removed by extraction, will readily absorb free colour acids, e.g., picric acid and certain azo-sulphonic acids, at the same time liberating an appreciable amount of free sulphuric acid, not necessarily equivalent in amount but at any rate somewhat similar. Fuller evidence acquired in this matter will be published at an early date. These are the main features of the development of the knowledge of neutral salt reactions, and of its ready application to a diversity of subjects, and in the latter connec tion considerable progress may still be looked for. Technical College, Bradford.

3

68. Platinium 69. Gold.. 70. Mercury 71. Thallium 72. Lead.. 73. Bismuth

74. Radium

Copenhagen, Valdemarsgade 3.

75. Thorium

76. Uranium ..

I

June 23, 1913.

7

4. Glucinium

5. Boron

6. Carbon

7. Nitrogen

8. Oxygen 9. Fluorine 10. Neon

II. Sodium 12. Magnesium 13. Aluminium 14. Phosphorus 15. Sulphur

THE SCIENTIFIC WEEK.

(From Our Paris Correspondent).

NEW METHOD TO FORETELL THE WEATHER: THE GUILBERT METHOD (Hitherto Unpublished). FOR the last few years a new method for forecasting the weather, the Guilbert method, has daily been enregistering new successes. Scientific men, such as Prof. Bernard Brunher, formerly Director of the Puy-de-Dôme Observa tory, M. Violle, the learned physician, member of the French Institute, and the late Tersserenc de Bort, already very justly appreciated the meteorologist Gabriel Guilbert. Violently controverted by the Control Meteorological Bureau of France, M. Guilbert has, however, received numerous encouragements from abroad. At Hamburg, at Valencia in Spain, at Belt in Holland, and also in Portugal, the meteorological observatories use his method of foretelling the weather.

In what does this method consist? M. Guilbert himself thus explains it to us :-The method of foretelling the weather at short spaces of time, known under the name of the Guilbert weather, is simply based on observation. M. Guilbert believes that the wind on the surface of the globe is the cause, at least apparent, of barometrical variations at twenty-four hours distance. So then, according to him, there is a relation of cause and effect between the speed and the direction of superficial winds and the consecutive variation of the pressure. Hence it is easy to conceive all the importance of this relation, if we consider that weather, in the widest sense of the word, depends, theoretically, on barometric pressure, and especially on the respective disposition of the centres of high and low

pressure.

The essential aim of the method is precisely the prevision of forecast of these oscillations of pressure, to arrive at which it employs a certain number of rules. The method is, however, extremely simple, in this sense, that it requires only one single observation, that of the wind, the easiest of all, but over vast extents as over a large part of Europe for example. This method eliminates all other indications; it does not take into consideration the thermometrical or hygrometrical variations, the zones of rain or of fine weather; it leaves aside the winds of mountains and high regions as well as the atmospherical calorific or magnetic observations. Of all the elements generally considered in daily forecasts of the weather this method utilises only the wind and the variation of

pressure.

But if the fundamental basis of the method is thus very simple, the application of the rules is more complicated and requires a veritable study. At the outset it is neces sary to discern the different relative or absolute speeds of the surface winds, so as to discover the winds that the

method designates as normal and abnormal, as convergent and divergent.

According to classical teaching, the wind is proportional to the gradient, that is to say, to the atmospherical slope, to the declivity of the air, so to say, compared with the declivity of the ground. The greater the importance of the slope, that is to say of the gradient, so much the more does the wind acquire speed. Now, M. Guilbert has remarked that on many days this notion was inexact. With a steep gradient, the wind remained weak, and inversely blew with force when the gradient was but weak.

It is from this observation M. Guilbert has deduced the fundamental principle of his method: the principle of normal wind. Normal wind is merely wind proportional to the gradient; abnormal wind will be so by excess if the wind is stronger than the gradient allows for theoretically, they will be abnormal by default if they are too weak. Now, winds abnormal by excess determine a barometrical rise, generally proportional to the abnormality observed in the twenty-four hours. Inversely the winds abnormal by default determine a fall of the barometer. Now a determining of these mere movements of barometric pressure

allows the forecast of the future of squalls, and also makes it possible to know if such or such depression will be filled up or hollowed out, and if consequently the wind is going to increase or decrease. In certain circumstances, when the abnormal winds by excess surround a centre of depression, this centre is completely destroyed: tempestuous winds sometimes-and thus the method foretells-are followed by a perfect calm in a delay of twenty-four hours, sometimes even in twelve hours. It is the phenomenon called in the Guilbert method by the name of “Compression of the Cyclone."

The distinction of the winds designated as convergent and divergent is not less important. The former have a tendency to contract the depression, to push it back, they constitute a resistance of the invading march of the cyclone or tend to destroy it; the latter, on the contrary, are attractive winds; they constitute centres of attraction of less resistance: they determine the fall of the barometer ard sometimes even create a hurricane.

Wind, both generator of tempests and calms; wind considered as the only regulator of atmospheric pressure tending ceaselessly to level if it is possible to thus express the idea—the aerial layers, such is the directing hypothesis of the Guilbert method.

The large proportion of successes obtained in the fore casts of the weather according to the above related principles shows incontestably that this point is the result of mechanical effects due to the mere action of the surface winds.

A DISEASE OF METALS.

The first contagious disease of metals was discovered several years ago, by some chemists, on tin. The disease of tin is now well known. Prof. Hanriot, Director of the Metal Tests at the French Mint, has just recently discovered a new disease with which alloys may be afflicted. The alloy (copper-aluminium), containing 97 per cent of aluminium and 3 per cent of copper, which hardens the former of the two metals, is employed especially in the manufacture of helmets and other military objects and utensils. Now, in the Government stores and depôts, especially at Orleans, it has just lately been observed that thousands of copper-aluminium utensils are afflicted with another, corroding the metal and making holes in it. As this epidemic disease, which spreads from one object to the French War Department possesses about 25 to 30 millions worth of francs of objects manufactured with this alloy, measures have been taken to discover the origin of the evil. MM. Hanriot and Le Chatelier, the learned chemist of the Academy of Sciences, have been asked to elucidate the problem.

According to M. Chatelier the origin of the disease is due to a defect in the cold-hammering, but this opinion did not resist the experiments of M. Hanriot, who noticed conditions a veritable migration of the copper takes place. that the copper-aluminium alloy was not stable. In certain The copper emigrates to form, with the aluminium, a bronze of aluminium (50 per cent of aluminium and 50 per cent of copper), which is a stable alloy. But by this emigration there are formed on the surface of the metal holes with sides sometimes as long as 2 centimetres.

This disease spreads by contact, and the metal suffering from it looks as if it were attacked by eczema. A light then be considered as lost and done for, as up till the grey spot appears at irregular intervals. The object may present time no remedy is known for this singular affection.

A NEW STEREOSCOPE.

When you look into an ordinary stereoscope there is a dissociation between the convergence which is preserved and the accommodation which is suppressed, by reason of the presence of the eye-glasses. Moreover, these latter and their mountings are a little joined to the effect produced, and the eyes cannot manage to get entirely free from them. Then, again, stereoscopic images are always small, and it is only, thanks to the enlargement by the