Obrazy na stronie

Meetings for the Week.

{ ,

Dec. 8, 1876. develops electricity, which acts upon the disks by attrac

MEETINGS FOR THE WEEK. tion in the direction of the electricity evolved. (2) This instrument being at rest, I poured upon it ether, and saw Monday, 18th.-Society of Arts, 8."(Cantor Lectures.) "The History immediately the disks hover, turn slightly, and soon stop.

of the Art of Coach Building," by Mr. G. A. 1 hrupp The cause of this phenomenon is the same, the electricity

Lecture V.--Rules of Coach-building, and Theories

applicable to the Carriages of the Future. produced by evaporation-a fact well known to science.

Medical, 8. (3) These facts (i and 2) being incontestable, let us pro

London Institution, 5. duce some analogous facts with the radiometer. (a) I TUESDAY, 19th.---Civil Engineers, 8. Anniversary). placed the radiometer in a part of the room so dark that

WEDNESDAY, 20th.-Society of Arts, 8. “The Centennial Exhibition,

Philade phia, 1876," by Prof. Archer. it did not turn. I then poured ether upon the covering,

Geological, 8. and immediately the radiometer began to turn somewhat

Meteorological,: 7.

THURSDAY, 21st.-Royal, 8.30. quickly, but in a direction contrary to that which it takes

Chemical, 8. when exposed to the light. After having turned thus for

Philosophical Club, 6.30. a few moments it stops, and resumes its former state of Friday, 22nd.-Quekett Club, 8. repose. According to the experiments i and 2 must not this fact be ascribed to electric action ? (6) M. Ducretet

TO CORRESPONDENTS. lias observed the change in the direction of the radiometer when drenched with ether; let us do the same. Whilst A. de Noé Walker.-Apply to Messrs. Brooke, Simpson, and Spiller the radiometer is in motion, and turning trom right to left, stating the purpose for which it is wanted.

E. Bevan. -Send us an account of the analysis when you have let us pour a little ether upon it; we then see the radio. meter change its direction, and turn from left to right. After a few moments it stops, and finally resumes its nor- IMPORTANT WORK ON DYEING AND mal course from right to left. Are we not to ascribe this

CALICO PRINTING. change of direction to an electric action? The experiment Second Edition, in One Large 8vo. Volume of 550 pages, strongly of M. Govi, showing that the watery vapour circulating bound in cloth, Illustrated with numerous Wood Engravings, round the radiometer gives it an accelerated motion,

and 57 Specimens of Printed and Dyed Fabrics,

Price 215. which ceases in course of time, does it not show electricity in action ? The new facts observed above (1, 2, and 3),

PRINTING: should they not be attributed to electric action? Yet we including an account of the most recent improvements in the

Use and Manufacture of Aniline Colours. are still very far from believing that the experiment has

By the late furnished us with sufficient data to arrive at a complete

Dr. F. CRACE-CALVERT, F.R.S., F.C.S. explanation of the phenomena of the radiometer. (4) We

Edited by constructed a radiometer, in which three platinum wires,

JOHN STENHOUSE, LL.D., F.R.S., sealed into the glass covering, support each at its interior end a small copper disk. Two of the disks are vertical,

CHARLES EDWARD GROVES, F.C.S. but one (to the left of the author's diagram) is horizontal. With this instrument I experimerted as follows:-1 placed

Manchester : PALMER & HOWE. London: SIMPKIN & Co.

made it.



a lighted candle near this radiometer; it turned then from BERNERS COLLEGE of CHEMISTRY,


in conjunction with the SCIENTIFIC DEPARTMENT of the radiometer was at rest I applied the current of a battery , ROYAL POLYTECHNIC INSTITUTION. of 3 or 4 elements to a small Ruhmkorff coil. The ends

Instruction and preparation in CHEMISTRY and the EXPERI.

MENTAL SCIENCES under the direction of Professor E. V. of the fine wire of this coil were applied, the one to the GARDNER, F.A.S., M.S.A. exterior end of the platinum wire to the left, and the other The Class Rooms are open from 11 to 5 a.m. and from 7 to 10 p.m. to that at the right, the positive pole being connected with daily the left hand, when the radiometer turned in the same di

Especialfacilities for persons preparing for Government and other

examinations. rection as above. If, whilst the radiometer was turning Private Pupils will find every convenience. under the influence of the electric current, a lighted candle Analyses, Assays, and Practical Investigations connected with was brought near, the speed of the rotation increased con

Patents, &c., conducted.

Prospectuses and jull particulars on application to Prof. Gardner, siderably, a proof that the two actions took place in the at Berner's College, 44, Berners-street, W., or at the Royal Polysame direction. We then placed the outer ends of the technic Institution. a galvanometer whilst the radiometer was turning under PATENTS:- Mr. Vaughan, F.C.S., British

Foreign, and Colonial PATENT AGENT. Special attention the influence of a gas-jet. The needle of the galvanometer given to Inventions relating to Chemistry, Mining, and Metallurgy. did not remain at rest, but described an angle of 5°. If the

*Guide to Inventors" Free by Post.-Ofhces, 67, Chancery Lane, poles are inverted the radiometer stops. "If the positive London, W.C., and 8, Houndgate, Darlington. pole of the battery is brought near the exterior either of Water-glass, or Soluble Silicates of Soda the base or the summit of the instrument it stops. The

and Potash, in large or small quantities, and either solid author expresses his intention of explaining these results in

or in solution, ai ROBERT RUMNEY'S, Ardwick Chemical
Works, Manchester.


STREET, offers Jewellers, Mineralogists, Lapidaries, and Scientific Information for Ladies !—In spite of all existing kinds), large Collections of Fine Hyacinths in all Colours,

specially Collectors of Rare Cut Gems (which he possesses in all the efforts of the educational powers that be to spread Clear Spanish Topazes, Blue and Yellow Amethysts, Jargon, scientific instruction amongst the people, the instances

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Pebbles. Polished Agates, &c., Starstones and Catseyes, Garnets, that daily crop up of the crass ignorance on matters of

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COMPANY'S EXTRACT OF MEAT. coolly informs us that this very safe and common aperient LIEBIG is an oily both from Russia and America, but that obtained from the

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und Sauces. Caution.-Genuine ONLY with laczimile latter country is esteemed the best.” We can fancy a

of Baron Liehig's signature across Labei. fond mother trying to cram half an ounce of Russian castoreum, membránous bag and all, down her lovely F.

W. HART, Manufacturer and Dealer in infant's throat, under the impression that it was a “very tory Fitter and Furnisher. Photographic Apparatus and Materials

Apparatus and Chemicals for Scientific Pursuits. Lałora. safe aperient.”


a future paper.


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Dec. 22, 1876.
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Repulsion Resulting from Radiation.


ground perfectly flat. a, c, c', and c" can therefore be THE CHEMICAL NEWS, sealed up by cementing flat transparent plates of glass,


quartz, rock-salt, &c., a, d, d', d" on to them. At right

angles to a b, and at the parts e, e', upright tubes, f e, fie', VOL. XXXIV. No. 891.

are sealed, one of them having an arm (8) blown into it for the purpose of attaching the apparatus to the pump. h, i, h', i' are glass beams made as light as possible con. sistent with the necessary stiffness. j k, j' k' are glass

fibres (103) cemented at j, j' to pieces of glass rod, and ON REPULSION RESULTING FROM

terminating at k, k' with a stirrup cut from aluminium RADIATION.-PART II.*

foil, in which the glass beams h, i, h', i' rest. In front of By WILLIAM CROOKES, F.R.S., &c.

these stirrups are thin glass mirrors (k, k'). At the ends

of the beam (h, i) are cemented very thin pieces of (Concluded from p. 254).

blackened pith, each i centim. square; and at the ends of

the other beam (h', i') are cemented pieces of platinum 115. It has already been said that when radiation falls on foil, also 1 centim. square. At l and l' are narrow slits, a thin surface of pith, the neutral point is low, whilst with with lamps behind them, so arranged that they send their a moderately thick piece of platinum it is generally high. rays of light respectively on to the

mirrors (k, k'), whence

When the I have constructed a double" torsion apparatus by means they are reflected back to the divided scale m. of which these adions can be easily studied. Fig. 10

torsion beams are not acted on by any force, the rays of shows the arrangement of apparatus. It consists of a | light both meet at zero (m), and there overlap, the

Fig. 10.

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torsion apparatus constructed as the one shown in fig: 7 slightest movement of either beam causing them to (102), with the exception of the arms being double. separate. Similar parts in each drawing are shown by similar letters. When the apparatus is full of air, a beam of radiation a b is a piece of thin glass tubing, sealed off at the end b, sufficiently wide to cover the whole window (c'') being and ground perfectly flat at the end a. In the centre a thrown upon the plates 1, k', the latter are instantly at. circular hole (c") is blown, and two others are blown at tracted, as shown by the movement of the reflected rays the parts c and c'; the edges of these holes are also of light (k m, k' m). On exhausting the tube, and trying

the effect of a hoć body at the central window from time * A Paper communicated to the Royal Society, March 20, 1875. to time, it is seen that the movement of the pith surface From the Philosophical Transactions o‘the Royal Society o London, (i) gradually diminishes, until at a certain point of exvol. clxv., pt. a.


Repulsion Resulting from Radiation.


Dec. 22, 1876. haustion (in this apparatus at about 50 millims. below a adduce a few experiments which have been devised vacuum) the neutral point for pith is obtained. On in- specially with the view of putting one or other of these creasing the rarefaction the pith is repelled by radiation, theories to the test. In giving what I conceive to be the platinum continuing to be attracted. On exhausting reasonable arguments against the explanations which the air still further (to about 28 millims.) the neutral have already been proposed, I do not, however, wish to point for the platinum surface is obtained, higher rarefac- insist upon any theory of my own to take this place. tions producing repulsion of each when radiation falls on Any theory will account for some facts; but only the true the pith and platinum surfaces (i, l').

explanation will satisfy all the conditions of the problem, Ai a rarefaction intermediate between the neutral point and this cannot be said of either of the theories I have for pith (50 millims.) and the neutral point for platinum already discussed. (28 millims.), the curious effect is produced of the same 118. The pendulum apparatus, described and figured beam of radiation thrown into the window (c") producing in paragraph 99, was specially devised to bear upon the repulsion of the pith and attraction of the platinum, the air-current and the electrical theory. On referring to the two rays of light (k m, k' m) each moving to the right, description of the experiments tried with it (Tables I. and, if a piece of ice is presented to the central window, and II.), it is seen that in air the ignited spiral produced to the left. By adjusting the internal tension of the attraction, whilst in a vacuum the same source of radiaapparatus, a point may be reached (about 40 millims. tion gave strong repulsion. Now the effect of raising a below a vacuum) at which the repulsion of pith and the platinum spiral to whiteness in the air would be to rarely attraction of platinum are exactly equal, and then the two the air all round, and the suddenness of its ignition would rays meeting at m do not separate, but together move to cause the air to be driven from it, as a centre, on all sides. the right or left.

Hence I was prepared to find that the pendulum would 116. A series of experiments have been tried with a be mechanically blown on one side by what might be view to ascertain whai influence the state of surface of likened to a miniature explosion of heated gas. But the the substance submitted to radiation has on the amount action was always one of attraction, whilst, when there or the direction of its movement. A torsion apparatus was no air at all present to be expanded and driven away was prepared similar to the one shown in fig. 7 (102), and by the hot platinum, the action was one of violent repuíhaving a thin disk of ivory at each end. One was coated sion. A possible explanation of the attraction in air in with lampblack, whilst the other retained its white polished this experiment may be given by assuming that the surface. The average of a number uf experiments showed pendulum was driven inwards by the rush of cold air that, under the influence of the same source of radiation supplying the place of that rising upwards from the hot acting for the same time (15 seconds), the white ivory spiral; but it is not likely that this action should so comwas repelled so as to send the luminous index 41'5 divi- pletely overcome the effect of expansive action ; and, sions of the scale, whilst the blackened ivory caused the moreover, it will only account for half the phenomenon index to move 46.8 divisions. These experiments were, (that in air), and leaves the still stronger action in a however, tried in 1873,* when I had not succeeded in vacuum entirely unexplained. getting anything like the delicacy I now obtain in the

Fig. II. apparatus; and I propose to repeat them under varied conditions before employing the results to found any arguments upon.

117. In my former paper on this subject (74, 75, 76, 77, 78) I have discussed various explanations which may be

d given of attraction and repulsion resulting from radiation; and in a lecture delivered before the Physical Societyt I entered more fully into the same arguments. The most obvious explanation is that the movements are due to the currents formed in the residual gas, which, theoretically, must be present to some extent even in those vacua which are most nearly absolute.

Another possible explanation is that the movements are due to electricity developed on the moving body, or on the glass apparatus, by the incident radiation.

A third explanation has been put forward by Professor Osborne Reynolds, in a paper which was read before the Royal Society on June 18th, 1874. Referring to the results of my experiments, Prof. Reynolds says that it is the object of his paper to prove that these effects are the result of evaporation and condensation. In my exhausted tubes he assumes the presence of aqueous vapour, and then argues as follows:-“When the radiated heat from a the lamp falls on the pith, its temperature will rise, and any moisture on it will begin to evaporate and to drive the pith from the lamp. The evaporation will be greatest on

f that ball which is nearest to the lamp ; therefore this ball will be driven away until the force on the other i 119. I have tried special experiments to put the air. becomes equal, after which the balls will come to rest,

current theory to a decisive test. Bulb tubes (84) and unless momentum carries them further.

On the other torsion apparatus (102) have been prepared, containing hand, when a piece of ice is brought near, the tempera- terminals of metal, ivory, glass, mica, or pith, in the form ture of the pith will be reduced, and it will condense the of thin flat surfaces. These surfaces have been placed at vapour and be drawn towards the ice."

an angle with the plane passing through the index and It is not my intention to recapitulate the arguments I suspending thread in such a manner that the action of have already brought forward against these three explana: heat would be to cause currents and drive them round like tions.

They are all fully given in my above-quoted the vane of a windmill. I, however, found the action of jecture before the Physical Society. I shall, however, heat in vacuo to be repulsion, and in air to be attraction;

and the latter was even strong enough to overcome the * The torsion apparatus with ivory terminals was exhibited in

action of the air-currents, which could not fail to be action at the meeting of the Royal Society, Dec. 11, 1873. 4 June 20, 1874 (Phil. Mag., August, 1871).

developed under the circumstances of the experiment.




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Dec. 22, 1876.
Physical and Chemical Properties of Ruthenium.

265 120. The pendulum apparatus has also been used to A similar experiment was next tried, only water was show that electricity is not the cause of the attraction and placed in the bulb before exhaustion. The water was repulsion. On referring to the description (99) it is seen then boiled away in vacuo, and the exhaustion continued, that the mass of magnesium forming the weight was in with frequent heating of the apparatus to dull redness, for metallic contact with the platinun wire which supported about forty-eight hours. At the end of this time the bar it, and that the upper end of this platinum wire was fused of aluminium was found to behave exactly the same as the into the glass tube, and passed thence to the outside. one in the former experiment, being repelled by radiation. With this I have tried numerous experiments bearing on Similar experiments, attended with similar results, the action of electricity. I have connected the projecting were tried with a platinum and with a glass index; and end of the platinum wire with “earth,” with either pole instead of water, iodine has been put into the bulb to of an induction-coil (the other pole being more or less in- begin with. sulated), with either pole of a voltaic battery, and with a It is impossible to conceive that in these experiments delicate electroscope ; I have charged it with an electro sufficient condensable gas or vapour was present to prophorus, and have submitted it to the most varied electrical | duce the effects Prof. Osborne Reynolds ascribes to it. conditions; and still, on allowing radiation to fall on the After the repeated heating 10 redness at the highest suspended mass, I invariably obtain attraction in air and attainable exhaustion, it is difficult to imagine that suffirepulsion in a vacuum. The heat has been applied from cient vapour or gas should condense on the movable index the outside, so as to pass through the glass, and also to be instantly driven off by a ray of light or even the inside by means of the ignited spiral; and the results warmth of the finger with recoil enough to drive backshow no difference in kind, but only in degree, under elec: wards a heavy piece of metal. trical excitement. I often obtain troublesome electrical 123. It seems to me that a strong argument against interference with the usual phenomena, but never of such Prof. Reynolds's theory (and also against the electrical a character as would lead me to imagine that the normal and air-current theories) may be drawn from the fact :hat results were due to electricity. I also obtain the normal the repulsion in a vacuum is not confined to those red adions whether the apparatus has been standing insulated and ultra-red rays of the spectrum which mainly produce in the air, or whether it has been completely immersed in dilatation of mercury in a thermometer, excite an electri. water connected electrically with "earth" or surrounded cal current between antimony and bismuth couples, and with wet blotting-paper.

cause a sensation of warmth when falling on the skin, but 121. The following experiment was suggested by Mr. that any ray from the ultra-red to the ultra-violet will proCromwell F. Varley, F.R.S., who informs me that he con- duce a similar effect. It cannot be reasonably argued siders the results conclusive against the electrical theory. that a ray of light, filtered through plates of glass and A torsion apparatus was prepared, as shown in fig. 11. alum (109), can instantly vapourise a film of moisture or The inside of the tube (a b) is lined with a cylinder of condensable gas from a surface on which it is caused to copper gauze, having holes cut in the centre (c) for the shine, or thať it can produce air-currents in the almost passage of the supporting thread (d c) and the index ray perfect vacuum surrounding the surface shone upon, or of light, and holes at each end to admit of the plates that it will produce electrical excitement on such a surface. (e, f) being experimented with. A hole drilled in the plate 124, Facis tested and verified by numerous experiments, (6) allows a wire to pass from the copper gauze to the but scarcely more than touched upon in the present paper, outside, so as to give me electrical access to the gauze are, I think, gradually shaping themselves in order, in my lining. Under the most diverse electrical conditions, , mind, and will, I hope, aid me in evolving a theory which whether insulated or connected with "earth," this apparatus will account for all ihe phenomena. But I wish to avoid behaves normally when heated; neither can I detect any giving any theory on the subject until I have accumulated electricity when the plate e or f is under the influence of a sufficient number of these facts. The facts will then radiation if I connect the wire g with a delicate electro- / tell their own tale ; the conditions under which they inscope. In experimenting with this apparatus I have variably occur will give the laws; and the theory will also completely immersed it in liquids, such as water, follow without much difficulty. In the eloquent words of solutions of metallic salts, ether, disulphide of carbon, &c. Sir Humphry Davy, “When I consider the variety of The heat has been applied in these cases by introducing a theories which may be formed on the slender foundation glass bulb containing water at different temperatures of one or two facts, I am convinced that it is the business and a thermometer (28). Under all these varied circum- of the true philosopher to avoid them altogether. It is stances the movements took place in a regular manner, more laborious to accumulate facts than to reason conand no electrical action whatever could be detected.

cerning them ; but one good experiment is of more value 122. I have already discussed Prof. Osborne Reynolds's than the ingenuity of a brain like Newton's.” theory of evaporation and condensation somewhat fully in the already quoted Physical Society paper.* I will, however, describe the following experiments, which I think prove that Prof. Reynolds has not suggested a theory which accounts for all the facts of the case, and

PHYSICAL AND CHEMICAL PROPERTIES OF therefore has not hit upon the true explanation. A thick and strong bulb was blown at the end of a piece

RUTHENIUM. of very difficultly fusible green glass, specially made for

By H. SAINTE-CLAIRE DEVILLE and H. DEBRAY. steam-boiler gauges. In it was supported a thin bar of aluminium at the end of a long platinum wire. The upper end of the wire was passed through the top of the tube RUTHENIUM, is heated in oxygen, is not transformed, like and well sealed in for electrical purposes (120). The osmium, into a product volatile at 100°, but yields an apparatus was sealed by fusion to the Sprengel pump, and oxide, RuO2, which does not sublime appreciably unless exhaustion was kept going on for two days, until an heated to bright redness. To obtain the hyper-ruthenic induction spark refused to pass across the vacuum. acid (RuO4) of Claus, the analogue of osmic acid (904), During this time the bulb and its contents were several it is necessary to attack ruthenium, well purified from times raised to a dull red heat. At the end of two days' osmium, with a mixture of nitre and potassa. It is thus exhaustion the tube was found to behave in the same converted into an orange-yellow soluble rutheniate, and manner as, but in a stronger degree than, it would in a the solution of this salt, saturated with chlorine and disless perfectly exhausted apparatus, viz., it was repelled by tilled in the water-bath in a urrent of this gas, yields light and heat of low intensity and attracted by cold. volatile hyper-ruthenic acid, which condenses in gold

coloured globules or crystals. The ruthenium employed Loc.cit.; also CHEMICAL News, July 17, 1874.

in the further experiments of the authors was obtained by



Physical and Chemical Properties of Ruthenium.


Dec. 22, 1876. the reduction of this acid, and consequently cannot con- perature hyper-ruthenic acid, Ruz08, in vapour, without tain any trace of the other metals of the platinum group. sensibly disengaging oxygen.

A solution of hyper-ruthenic acid in potassa, treated On this property is founded another method of analysis, with alcohol, gives oxide of ruthenium, which is reduced which we have tried, and which gave results corresponding to a metallic state by coal-gas at a temperature slightly with those cited above. Conforming to the nomenclature elevated. The metal is afterwards alloyed in a crucible of adopted by M. Fremy when he discovered osmious acid, charcoal made in a retort, purified by chlorine, with five and respecting as much as possible the nomenclature of or six times its weight of pure tin. The ingot, treated Claus, we shall propose to callwith boiling muriatic acid, which dissolves the excess of Ruthenous Acid, RuOz, giving with potassa yellowtin, leaves an alloy of ruthenium and of tin crystallised in

orange solutions. cubes, having the planes of a rhomboidal dodecahedron Hepta-ruthenic Acid, Ruzon, giving with potash a black (angles at goo and 135°), and containing equal equivalents salt, of which the solution is deep green. of tin and ruthenium. We grind it finely in a glass mor- Finally, Hyper-ruthenic Acid, the acid RuO4 of Claus, tar, and it is introduced into a small boat of purified which does not combine with potassa, and of which charcoal, which is strongly heated in a porcelain tube the characteristic property is to be volatile, to possess traversed by a current of dry and pure muriatic gas until even below 100° à considerable vapnur-tension, and the matter no longer loses weight. The tin is volatilised to decompose with explosion at 108°, as we have unentirely in the state of protochloride, and we recover, with- happily learnt at the expense of our stock of ruthenium. out any loss, the weight of the ruthenium upon wbich we Analysis of Ruthenium and its Alloys.-Though the have operated, but it is transformed into a crystalline purity of the ruthenium employed in our researches was matter." We obtained for the density of this matter the guaranteed by its method of preparation, we have neverfollowing numbers :

theless analysed it. We shall describe in detail the meWeight in the air at 21° and 760 m.m...

thod used for this analysis, which is suitable, as well for

74'2490 grm. Loss of weight in water at 21°

pure ruthenium as for its alloys. We attack o'5 grm. of

6•0265 grm. Futhenium with a mixture of 5 grms. potassa and 2 grms. Density at zero ..


pure nitre in a gold crucible, and heat to redness. The We admit in all these calculations the coefficients of metal disappears entirely, yielding a limpid liquid, which dilatation published by M. Fizeau in the Annuaire du we dissolve in water after solidification and cooling. The Bureau des Longitudes.

crucible is washed with pure hypochlorite of soda, and The determination of pulverulent matters like ruthenium the whole liquid transferred to a distillatory vessel of requires minute precautions, without which we dot not glass consisting of a balloon with a ground stopper, and obtain accordant numbers, even if we operate on one and fitted with two tubes blown to the balloon, one of which the same substance. But we cannot describe here in de. serves to introduce a current of chlorine into the liquid, tail the apparatus which we were obliged to employ to

and the other serves for the exit of the vapours disengaged, moisten completely the matter, and not to leave in the in and conducts them into another balloon containing a soluterior of the powder any trace of gas, and to avoid other tion of potassa. The ruthenite of potassa is first saturated causes of error.

with chlorine; the solution, at first orange, becomes a When hyper-ruthenic acid is prepared by passing blackish green and then a golden yellow, because there are chlorine into a concentrated solution of the orange ru- formed successively hepta-rutheniate, KO,Ruzon, and theniate of potassa, there is a moment when the liquor be. hyper-ruthenic acid. We heated then the balloon in comes deep green, and is filled with small black crystals. the water-bath to 80°, continuing to pass a slow current of If we decant at this moment we may isolate the crystals, chlorine. Yellow globules or crystals of hyper-ruthenic purify them from their mother-liquor and from chloride of acid are condensed in the tube which connects the balloon potassium by a rapid washing, and finally dry them, first of the receiver, and were gradually carried into the alkaon unglazed porcelain, then in a vacuum over caustic line liquid. With 30 grms. of potassa in the receiver we potash and lime. These crystals have very brilliant planes, are sure not to let hyper-ruthenic acid escape, if the cur. which are orthorhombic octahedra, derived from a prism rent of chlorine is not intense enough completely to satuof 117°. They are isomorphous with permanganate of rate the potassa. Nevertheless, we adapt to the receiver potassa. The solution of this salt is a deep greenish an abducing tube plunging into alcohol, which would black, like the salt itself. It decomposes very rapidly arrest the least traces of hyper-ruthenic acid, and convert into oxide of ruthenium, which is deposited, and into them into chloride of ruthenium. It must be noted that orange rutheniate of potassa. Hyper-ruthenic acid, neither curks, nor especially caoutchouc, can serve to close RuO,, does not seem able to combine with bases. If a or to connect the different pieces of this apparatus. fragment of it is dropped into solution of potassa it is dis- We must not expect to distil all the rutheniumin a single solved very slowly, disengaging oxygen, and producing operation. We let the liquid of the balloon cool, we renthe deep green salt with which we are now engaged. der it alkaline by adding a few pieces of potassa, and we This salt is composed of,

recommence the preceding operation by putting into the Ruthenium

receiver a fresh solution of potassa. If the liquid is no 1034 50'00 Ruz

= 50-34 Potassa ..

longer coloured, at first green then orange-yellow, on the 469

22:44 KO = 22.66 Oxygen

first contact with alcohol, this is a proof that the distilla569 27:46 07 27'00 Water

tion no longer gives hyper-ruthenic acid : the operation 8 0:38

is then terminated.

To withdraw ruthenium from the alkaline solutions 2080 100'28

where it is condensed, we add to these a small quantity of The salt, if weighed in a platinum boat placed in a glass alcohol; the greenish liquor becomes orange-yellow, then tube, and gently heated in a current of hydrogen, takes turbid, and deposits even in the cold oxide of ruthenium, refire, disengaging much water. If we replace hydrogen by taining a little alkali,which is carried off by washing first with carbonic acid a fresh quantity of water distils. If this water, afterwards with a dilute solution of sal-ammoniac, and water is collected in a chloride of calcium tube, and its finally with pure water. The filter upon which we reweight determined, we may deduce the quantity of oxygen ceived the oxide of ruthenium is introduced into a countercontained in the acid of the salt. There remains in the poised boat of porcelain, which is itself placed in a larger boat a mixture of ruthenium and of carbonate of potassa, capsule covered with a funnel, by the tube of which coal. which is weighed with the usual precautions, and which gas is caused to enter. When the air has been expelled is separated with the greatest facility. Chlorine decom- from the funnel we heat the capsule on a gas-furnace at a poses the new salt, Ru207,KO, or Rú203K, taking posses- temperature not exceeding 500°; the oxide of ruthenium sion of the potassium, and giving even at a common tem- | is reduced at first, and the paper is carbonised. We then


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