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172

Chemical Notices from Foreign Sources.

space-filling power of one stere, though there occur, e.g., in water of hydration = HO, certain condensations or expansions of individual elements which, as will subsequently appear, are characteristic of organic nuclei. A second very remarkable fact is the extraordinary constancy of the voluminar constitution with which certain elements and their compounds are contained in the most different groups. A third very important fact is the simplicity of the volume-molecules of all salts. Their volume-molecules are almost always monatomic, or at most di-atomic, the latter being the case only in iron spar, calcareous spar, and sodic nitrate.

Die Chemische Industrie.
No. 1, Jan., 1879.
Manufacture of Potassium Iodide.-E. Schering.-

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CHEMICAL NEWS,
April 18, 1879.

pressed, and sublimed. (2.) The mother-liquors are treated with sodium sulphite or bisulphite till the precipitated iodine is converted into hydriodic acid, which is then precipitated as cuprous iodide by a solution of copper sulphate and sodium sulphite. (3.) The iodine in the mother-liquors is concentrated by fractionated evaporation and crystallisation, and the iodine, mixed with a proportionate quantity of sodium sulphite or bisulphite, is recovered by distillation from the acidified liquid.

Efficacy of Compounds Employed as "Antichlore."-Dr. G. Lunge.-The author has submitted the modus operandi of some of these agents to a critical examination. The hyposulphite of soda (now thiosulphate) was said by Fordos and Gélis to undergo a direct conversion into sulphate. Its reaction with chlorine, as well not at once washed out, attacks the iron of the machinery, as that of the sulphites, gives rise to free acid, which, if forming injurious salts which render the paper brittle, Alkali-yellow, or spotty. There is no sufficient proof that the use of hyposulphite leads to the deposition of sulphur and the formation of acids by its gradual oxidation if the half-stuff has been properly washed. The efficacy of hyposulphite is much less than has been assu ned. Ammonia as an antichlore appears to act only at an elevated temperature with the emission of an unbearable odour.

Process for the Extraction of Sulphur from waste, Gypsum, Heavy Spar, and Sulphurous Acid, and recovery of the Earths previously Combined with Sulphur in the State of Carbonates.-Max Schaffner and W. Helbig.-This process cannot be fully described without the accessory plates. It is based upon the decomposition of calcium sulphide and magnesium chloride, which latter salt has no action upon calcium carbonate. The residue from this reaction, after the expulsion of the sulphuretted hydrogen and which contains magnesia and calcium chloride, is exposed to the action of carbonic acid, when magnesium chloride is reproduced and calcium carbonate formed.

No. 2, February, 1879.

Report on the Stassfurt Industry.-Dr. B. Bernhardi. -The improvements recently introduced aim chiefly at effecting economy in the consumption of carnallite and of fuel. It is proposed to evaporate the various liquors in closed boilers under a slight pressure. Continuous evaporation is likewise suggested, the difficulty being the removal of the salts from the heated surfaces as deposited. The conversion of potassium chloride into sulphate by double decomposition with Epsom salts is advantageously effected under Dr. Borsche's patent. The mixed salts are successively lixiviated with quantities of water insufficient for complete solution. The bulk of the magnesium chloride is removed in the first liquors. Many practical men, however, still prefer to treat the potassium chloride with sulphuric acid in a Jones salt-cake furnace.

Action of Magnesium Chloride upon Steam Boilers with reference to the Magnesia Process of Purifying Feed-water.-E. Boblig.-The author concludes from his experiments that magnesium chloride has no corrosive action as long as a slight excess of magnesium carbonate is present.

No. 3, March, 1879. Meeting of the Association for Promoting the Interests of German Chemical Industry. In a petition to the Reichstag concerning the use of alleged poisonous colours, the Association point out that certain dyes, such as red corallin and aurantia, denounced as poisons, have subsequently been proved perfectly innocent. They pray that no colour may be prohibited till it has been formally pronounced dangerous to public health by a commission of specially qualified chemists and physiologists after a due scientific examination. At the sessions of February 23, 24, and 25 a long debate ensued on the protective duties to be imposed on foreign chemicals, and a tariff was agreed upon to be submitted to the Reichstag.

South American Production of Iodine.-Dr. G. Langbein. The processes in use for separating iodine from the mother-liquors of the nitre refineries may be divided into three classes. (1.) The liquors, without previous concentration, are mixed with a quantity of sodium sulphite corresponding to the iodine present, the iodine separated out is filtered through linen bags, washed,

Chemiker Zeitung.

No. 12, 1879.

Adulteration of Wax.-Dr. Max.- Bee's-wax is often sophisticated to the extent of 33 to 50 per cent with ceresin, a mixture of refined earth-wax and caranaubawax. Pure bee's-wax has a higher specific gravity (0°94 to o'97) than these ingredients or than the mixtures, which range from 0.876 to 0.937. Prof. v. Wagner recommends the sample to be placed in dilute alcohol of sp. gr. '945, and rejected as impure unless it floats.-Dingler Polyt. Journal.

Detection of Starch in Milk.-Dr. Vulpius coagulates the sample with a few drops of acetic acid, heats to a boil, filters, and adds to the clear whey an aqueous solution of iodine, which at once produces a blue cloud if starch be present; 5 milligrms. were thus distinctly recognised in 5 c.c. of milk.-Pharm. Zeitung.

Chloride of magnesium is recommended as a fluid for filling wet gas-meters.

No. 13, March 27, 1879.

Distillation of Coal-tar.-The author gives an account of the distinctions between the products obtained by the dry distillation of wood, peat, lignite, and coal, and shows that according to the recent experiments of Letny, Liebermann, and others, wood-tar and petroleum-tar, &c., if passed through ignited tubes, yield the same products as coal-tar, which he considers may be of great importance for the production of the aniline and alizarin colours. He then gives an account of the distillation of coal-tar with especial reference to anthracen.

At Dortmund, on March 22, Dr. Schridde delivered a lecture on "Chemistry as a Trade, an Art, and a Science." In Switzerland the factory inspectors receive a yearly salary of 6000 francs, with an addition of 7 francs daily for their expenses when travelling on official business and 5 francs more if detained over night.

Moniteur Scientifique, Quesneville.
February, 1879.

This issue is almost entirely taken up with a transla. tion of Sir B. C. Brodie's well-known "Chemical Calculus," a continuation of the discussion between MM. Berthelot and Pasteur, a notice of foreign chemical researches consisting entirely of extracts from the Berichte

NEWS

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Royal Institution of Great Britain.-The following are the arrangements for the Lectures after Easter :

Ernst Pauer.-Three Lectures on Schubert, Mendelssohn, and Schumann (with Musical Illustrations); on Tuesdays, Aprill 22 to May 6.

Professor Dewar, M.A., F.R.S.- Fives Lectures on "Dissociation;" on Thursdays, April 24 to May 29.

H. H. Statham.-Four Lectures on the Leading Styles of Architecture Historically and Esthetically Considered; on Saturdays, April 26 to May 17.

Professor Karl Hillebrand.-Six Lectures on the Intellectual Movement of Germany from the Middle of the Last to the Middle of the Present Century; on Tuesday, May 13 Mondays, May 19, 26, June 2; Tuesday, June 10; and Thursday, June 12.

John Robert Seeley, M.A., Professor of Modern History, Cambridge.-Four Lectures, on Tuesdays, May 20, 27, June 3; and on Thursday, June 5.

Professor Henry Morley.-Three Lectures on Swift; on Saturdays, May 24 to June 7.

The following are the probable arrangements for the Friday evening Meetings after Easter, to which Members and their friends only are admitted.

Friday, April 25.-Francis Galton, M.A., F.R.S., M.R.I. Generic Images.

Friday, May 2.-Professor John G. M'Kendrick, M.D. The Physiological Action of Anæsthetics.

Friday, May 9.-Sir John Lubbock, Bart., M.P., F.R.S., M.R.I. The Habits of Ants.

Friday, May 16.-Professor A. Cornu. Etude Optique de l'Elasticité. (In French.)

Multiple

Friday, May 23.-W. H. Preece, M.R.I. Telegraph, or Duplex and Quadruplex Telegraphy. Friday, May 30.-Grant Allen. The Colour-sense in Insects; its Development and Reaction.

Friday, June 6.-Professor Dewar, M.A., F.R.S. Friday, June 13.-Frederick J. Bramwell, F.R.S. The "Thunderer" Gun Explosion.

Another Agricultural College.-A correspondent of The Live Stock Journal writes as follows:-"With considerable satisfaction I learn that the starting of another Agricultural College is already under contemplation, for it has long been evident that the Cirencester institution has neither attained the position which its promoters had in view, nor conferred on the agriculture of the country the benefits which were reasonably expected from it. Í hail therefore with pleasure the intimation that the four leading professors at Cirencester, viz., Professors Church, Tanner, Fream, and Sheldon, having been requested by influential persons to consider the idea, are already reducing to form the scheme of a second Agricultural College, for which, I have no doubt, they will receive all the help and patronage that are necessary to bring their project into successful operation. There is, indeed, room for several agricultural colleges, and no doubt the Cirencester one would have had a better tale to tell if two or three rival establishments had existed to spur it on. I regard the starting of a second Agricultural College in England as an event that is calculated to do a muchneeded service to the parent institution, and I venture to predict that each of the two colleges will do better than the single one has hitherto done, provided the Council will seriously take in hand those changes which are evidently so much needed at Cirencester."

NOTES AND QUERIES.

Honey.-Can any of your readers give me references to any late (within ten years) investigations of the chemical composition of honey?-E. H. S.

Insurance of Tar Distilleries.-Can any of your readers give the name of any Fire Insurance Office of good standing which effects insurances on risks as hazardous as tar distilleries?-W. A. R.

Testing of Coal-Tar Products.-(Reply to T. C. W.)-The tional distillation, observing the proportions by volume passing ov r liquid products-naphthas, benzols, phenols, &c.-are tested by fracbetween certain temperatures, and in the case of phenol observing also the proportion crystallising, and taking the melting-point of this. These test-proportions, the temperatures at which they shall pass over, and in the case of phenol the melting-point, are us ally fixel by the trade contract. I know no book containing an account of the e methods, which are simple cases of fractional distillation. Information on the testing of anthracen and the other solid products, as also of the aniline colours, &c., will be found usefully given in Bolley and Kepp's "Manuel Pratique d'Essais et de Recherches Chimiques Appliqués aux Arts et à l'Industrie." Paris: F. Savy, 24, Rue Hautefeuille.-WATSON SMITH, F.C.S., F.I.C.

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Appearance in

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174

Composition and Quality of the Metropolitan Water.

COMPOSITION AND QUALITY OF THE

MARCH, 1879.

METROPOLITAN WATER.

THE following are the returns of the Society of Medical Officers of Health:

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West Middlesex

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0.008 0.165 0.062 21.20 8.020 0*720
0'000 0·007 0120 00б4 21:00 8°170
0'000 0005 0135 0.075 21.00 7.840
0'000 0'008 0126 0.064 19.80 7.280
0'000 0.00б 0135 0.079

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21:50 8-120

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1'152 1700

148 4:20

Other Companies.

Kent..

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East London

0'000 0·004 0150 0.037
0'000 0008 0126 0.064 23.80 8.840 0.940 1290 2100 165 4:20

The quantities of the several constituents are stated in grains per imperial gallon.

NOTE. The amount of oxygen required to oxidise the organic matter, nitrites, &c., is determined by a standard solu tion of permanganate of potash acting for three hours.

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IV. A New Theory of Terrestrial Magnetism. By Profs. Perry LA

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V. The Jablochkoff Candle: Its Practical Results in London.
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VI. The Tornado at Wisconsin in 1878.
VII. The Electric Light for India.
VIII. Painless Death.
Correspondence-The Sea-Serpent-Spider's Web for Micrometers
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Reviews of Scientific Works-Science Notes-Proceedings of

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THE CHEMICAL

VOL. XXXIX. No. 1013.

I now propose to give a short description of the methods NEWS.I have employed for preparing the pure platinum and iridium necessary for the manufacture of the alloy, which I call "iridio-platinum," and it is upon the distinguishing characteristics above-mentioned that my method of separation is chiefly founded.

THE PREPARATION IN A STATE OF PURITY
OF THE GROUP OF METALS
KNOWN AS THE PLATINUM SERIES,
AND NOTES UPON

THE MANUFACTURE OF IRIDIO-PLATINUM.*
By GEORGE MATTHEY.

In this paper it is not my intention, nor should I be able, to refer generally to the results of work in the various branches of platinum metallurgy carried out by my firm, who, as is well known, have been associated with the development of this special field of industry from its earliest infancy; but I shall confine myself simply to that section of it upon which my personal attention has of late years been specifically concentrated in order to meet and comply with the requisition of the Bureau Internationale des Poids et Mesures, the Section Françaises de la Commission Internationale du Mètre, and of l'Association Géodésique Internationale (all of them important scientific committees, formed with the object of arriving at an accurate and definite solution of the long agitated question of standard weights and measures), and also at the demand of the French Minister of War, for an alloy the best adapted for the manufacture of the international metre and kilogram standard, and the geodesique_rule; and in my endeavour to solve this difficult problem I have had the great advantage of being able to consult those distinguished men, MM. Henri Sainte-Claire Deville and Henri Debray, of Paris, and have also had the benefit of the excellent and valued advice of M. Stas, the celebrated Belgian chemist, to all of whom the scientific world owe so much, and to whom I desire to offer my warmest thanks. In a paper of this kind it would be superfluous for me to enter into any of the already published details concerning the existence and collection of what is known as platinum-dust or mineral. It is sufficient for me to observe that the six metals (of which platinum is the chief) usually found more or less in association in their native state, present characteristics of interest beyond their metallurgical utility, which are, perhaps, worth alluding to en passant. It is, for instance, a curious fact that the group should consist of three light and three heavy metals, each division being of approximately the same specific gravity-the heavier being (in round figures) just double the density of the lighter series.

Thus we find osmium, iridium, platinum forming the first division, of the respective specific gravities of 22:43, 22:39, 21:46; whilst ruthenium, rhodium, and palladium are represented by the figures 1140, 1136, 11, the average densities of the heavy and light divisions thus being respectively 22:43 and 11.25.

But a more interesting and important classification is what I may designate as a first and second class series, from the more important view of their relative properties of stability. Thus platinum, palladium, and rhodium form the first or higher class, not being volatilisable in a state of oxide; iridium, osmium, and ruthenium forming the second or lower class, their oxides being more or less readily volatilised.

The oxide of iridium is effected at 700° to 800° C., and entirely decomposed at 1000°, whilst osmic and hyporuthenic acids are volatilised at the low degree of 100°, the latter exploding at 108°. The chlorides of these metals can be sublimed at different temperatures (as also the protochloride of platinum).

A Paper read before the Royal Society.

Platinum.

The preparation of this metal to a state of purity is an operation of extreme delicacy. I commence by taking ordinary commercial platinum; I melt this with six times its weight of lead of ascertained purity, and, after granution of 1 volume to 8 of distilled water. lation, dissolve slowly in nitric acid diluted in the proporThe more readily to ensure dissolution, it is well to place the granulated alloy in porcelain baskets such as are used in the manuWhen the first charge of acid is sufficiently saturated, a facture of chlorine gas for holding the oxide of manganese. fresh quantity should be added until no more action is apparent; at this stage the greater part of the lead will have been dissolved out together with a portion of any copper, iron, palladium, or rhodium that may have been present. These metals are subsequently extracted from the mother-liquors, the nitrate of lead by crystallisation, and the remaining metals by well-known methods. The metallic residue now obtained will be found in the state of an amorphous black powder (a form most suitable for further treatment), consisting of platinum, lead, and small proportions of the other metals originally presentinsoluble in nitric acid. After digesting this compound the iridium existing as a brilliant crystalline substance in weak aqua regia, an immediate dissolution takes place of the platinum and lead, leaving the iridium still impure, but effecting a complete separation of the platinum.

is added sufficient sulphuric acid to effect the precipitaTo the chloride of platinum and lead after evaporation tion of the whole of the lead as a sulphate, and the treated with an excess of chloride of ammonium and chloride of platinum after dissolution in distilled water is sodium, the excess being necessary in order that the precipitated yellow double salt may remain in a saturated solution of the precipitant. The whole is then heated to about 80', and allowed to stand for some days; the ammonio-chloride of platinum will settle down as a firm deposit at the bottom of the vessel, whilst if any rhodium, will be coloured a rose tint, occasioned by a combination as is generally the case, is present, the surface liquor of the salts of the two metals.

The precipitate must be repeatedly washed with a saturated solution of chloride of ammonium and subsequently with distilled water charged with pure hydrochloric acid. This is necessary for its purification. The small quantity of the double salt which will be taken up and held in solution is of course recovered afterwards. Rhodium may still exist in the washed precipitate, which must therefore not be reduced to the metallic state until its separation is completed, and this is best effected by mixing with the dried compound, salts of chloro-platinate and chloro-rhodiate of ammonia, bisulphate of potash with a small proportion of bisulphate of ammonia, and subjecting to a gradual heat brought by degrees up to a dull red in a platinum capsule, over which is placed an inverted glass funnel. The platinum is thus slowly reduced to a black spongy porous condition free from water, nitrogen, sulphate of ammonia, and hydrochloric acid, the rhodium remaining in a soluble state as bisulphate of rhodium and potash, which can be dissolved out completely by digesting in boiling distilled water; a small quantity of platinum will have been taken up in a state of sulphate, but is regained by heating the residue (obtained on evaporation) to redness, at which heat it is reduced to the metallic condition, the rhodium salt remaining undecomposed.

By the method above described the platinum is freed not only from rhodium, but from all other metals with which it may have been contaminated, and is brought to

176

Preparation of Metals of the Platinum Series.

{CHEMICAL NEWS

April 25, 1879.

a state of absolute purity, of the density 21:46, the highest | charcoal crucible, is melted into an ingot, and after being degree obtainable.

Iridium.

In the preparation of this metal when intended to be used for the manufacture of iridio-platinum alloy, I have arrived at freeing it to the utmost possible extent from all its associate metals, except platinum, disregarding the presence of the latter; the proportion of which, once determined, would only form matter of calculation in the final operation of mixing my alloy.

In practice, the purest iridium which can be obtained from its ordinary solution (deprived of osmium by long boiling in aqua regia and precipitated by chloride of ammonium) will almost invariably contain traces of platinum, rhodium, ruthenium, and iron.

I fuse such iridium in a fine state of division with ten

times its weight of lead, keeping it in a molten state for some hours, dissolve out the lead with nitric acid, subject the residue to a prolonged digestion in aqua regia, and obtain a crystalline mass composed of iridium, rhodium, ruthenium, and iron, in a condition suitable for my further treatment. By fusion at a high temperature with an admixture of bisulphate of potash, the rhodium is almost entirely removed, any remaining trace being taken up together with the iron in a later operation. The iridium so far prepared is melted with ten times its weight of dry caustic potash, and three times its weight of nitre, in a gold pan or crucible; the process being prolonged for a considerable time to effect the complete transformation of the material into iridiate and ruthenate of potash, and the oxidation of the iron; when cold, the mixture is treated with cold distilled water. The iridiate of potash of a blue tinge will remain as a deposit almost insoluble in water, more especially if slightly alkaline, and also the

oxide of iron.

This precipitate must be well washed with water charged with a little potash and hypochlorite of soda until the washings are no longer coloured, and then several times with distilled water.

The blue powder is then mixed with water strongly charged with hypochlorite of soda, and allowed to remain for a time cold, then warmed in a distilling vessel, and finally brought up to boiling-point until the distillate no longer colours red, weak alcohol acidulated with hydro

chloric acid.

The residue is again heated with nitre and potash water charged with hypochlorite of soda and chlorine, until the last trace of ruthenium has disappeared.

Further, to carry out the purification, the blue powder (oxide of iridium) is re-dissolved in aqua regia, evaporated to dryness, re-dissolved in water, and filtered.

The dark-coloured solution thus obtained is slowly poured into a concentrated solution of soda and mixed with hypochlorite of soda, and should remain as a clear solution without any perceptible precipitate, and subjected in a distilling apparatus to a stream of chlorine gas, should not show a trace of ruthenium when hydrochloric acid and alcohol are introduced into the receiver. In this operation the chlorine precipitates the greater part of the iridium in a state of blue oxide, which after being collected, washed, and dried, is placed in a porcelain or glass tube, and subjected to the combined action of oxide of carbon and carbonic acid obtained by means of a mixture of oxalic with sulphuric acid gently heated.

The oxide of iridium is reduced by the action of the gas leaving the oxide of iron intact, the mass is then heated to redness with bisulphate of potash (which will take up the iron and any remaining trace of rhodium), and after subjecting it to many washings with distilled water, the residue is washed with chlorine water to remove any trace of gold, and finally with hydrofluoric acid, in order to take out any silica which might have been accidentally introduced with the alkalies employed or have come off the vessels used.

The iridium, after calcination at a strong heat in a

broken up and boiled in hydrochloric acid, to remove any possible trace of iron adhering to it through the abrasion in breaking up, should possess if perfectly pure a density of 22:39; but, as iridium prepared even with the utmost care will still contain minute though almost inappreciable traces of oxygen, ruthenium, rhodium, and possibly iron, the highest density I have yet attained is 22.38.

Alloy of Iridio-Platinum.

This compound metal possesses physical properties of great value, forming a beautiful example of the effect of a careful combination of the opposite characteristics of its component parts. Thus, the extreme softness and expansiveness of pure platinum and the brittleness and excessive hardness of pure iridium, produce, by combina. tion in judicious proportions, a perfect and homogeneous alloy, possessing the necessary mean of these properties to render it suitable for many important purposes, amongst others that of the special object to be attained to meet the requirements for an unalterable standard metal, for which it is peculiarly adapted.

In the manufacture of the prototype metres and the geodesique rules (each 4 metres in length) ordered from my firm by the Comité Internationale des Poids et Mesures, the Association Geodesique Internationale, and the French Minister of War, I proceeded in the following manner with the platinum and iridium prepared as described above.

Operating upon a charge of 450 ounces of platinum and 55 ounces of iridium, I commenced by melting these metals together and casting into an ingot of suitable shape, which I then cut into small pieces with hydraulic machinery. After re-melting and retaining in a molten condition under a powerful blast of oxygen and common gas for a considerable time, I re-cast and forged at an intense white heat under a steam hammer, the highly polished surfaces of which were cleaned and polished after each series of blows-when sufficiently reduced it was passed through bright polished steel rollers, cut into narrow strips, and again slowly melted in a properly shaped mould, in which it was allowed to cool. I thus obtained a mass of suitable shape for forging, perfectly solid, homogeneous, free from fissures or air-holes, and with a bright and clean surface at bottom and sides as at top. At the first forging a bar was obtained 35 centims. long, 7'5 wide, 2.5 thick, which weighed—

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10.814 grms. 10'315 17

In water at 60° F. Showing a density at zero of 21.648 This was then passed through highly polished rolls until of a length of 4080 centims., 21 millims. in width, and 5 millims. thick, to which a perfectly rectangular form was subsequently given by drawing it through a series of plates, and thus prepared the rule was in a condition to receive the beautiful polish of which this alloy is susceptible.

After passing it through each hole the metal was annealed by means of a jet of gas and oxygen to a heat just below nielting-point, and each time throughout after forging, rolling, and drawing was exposed to the action of melted borax, and boiled in concentrated hydrochloric acid to remove any possible trace of adherent iron or other impurity.

A piece cut from the end and presented to the French Academy of Sciences gave the following results:Weight in air water .. Showing a density of..

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116.898 grms. 111'469 " 21.516

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