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some red-hot magnesium or lithium,” | Fahr. below zero, and into a block of until, most of it having combined with opaque ice at 310° below zero.? the metal, a small quantity of argon is But these physical properties tell us obtained, which yet is never quite free nothing about what argon is, and all from nitrogen. Or else atmospheric attempts to unveil its chemical nature air mixed with some oxygen is sent have bitherto failed. Even Moissan, through a tube in which tric sparks with his powerful electric furnace, are passed, and while the nitrogen of could not overpower its inertness. the air is thus induced to combine with Neither fluorine, which is one of the oxygen, argon remains ; but this oper- most active elements, nor titanium, ation, too, must be continued for hours, boron, and lithium, which readily conand the produce is never pure. There bine with nitrogen, could be induced to is, tinally, a third method, namely, to combine with argon. Berthelot alone, send air through a porous membrane using the silent electrical discharge, which separates gases of different dens- has achieved a partial success : he ities, but nothing is gained by it in made argon combine with benziue and rapidity. All this is of course most obtained a yellow resinous substance ; wearisome, and even has been made a but the quantity of argon he had rereproach to Lord Rayleigh and Pro-ceived from Professor Ramsay was so fessor Ramsay ; but chemical bodies small (a little over two cubic inches) must be taken as they are, and those that nothing could be said about the of them wbich, like argon, refuse to produce of combination beyond its yield to chemical routine are perhaps being similar in aspect to the products the most conducive to an extension of of combination of nitrogen with benchemical knowledge.

zine. Negative properties is thus all Whenever a new body is discovered, we know about the chemical nature of its leading physical properties are al- argon. Even the spectroscope — this ways the easiest, and therefore the precious reconnoitring instrument - is first, to be determined. We thus know undecided in its indications. The about argon that it is a colorless and spectrum of argon is quite character. inodorous gas, having about twenty istic. No other known gas or vapor, times (19.7 to 19.9) the density of Mr. Crookes writes, gives a similar hydrogen, and much more soluble in spectrum. But when a glass tube filled water than either oxygen or nitrogen. with argon is made to glow under the Accordingly, the air which is dissolved electrical discharge, and the glow is in water contains a larger proportion of examined with the spectroscope, two argon than free atmospheric air ; in different spectra appear - one of them unboiled water we drink a greater pro-chiefly in the red and the other chiefly portion of dissolved argon than we in the blue — according to the energy inhale of it while breathing, and this of the discharge. These two spectra property may prove of great impor- may of course indicate that argon is a tance for vegetation if argon enters, as mixture of two gases, although it is it probably does, into the composition known that nitrogen and other gases of plants. It requires also a very low

: The corresponding temperatures for nitrogen temperature for liquefaction. Olszew

are -318° and -353° Fahr. As to oxygen, it has ski, the Cracow professor, whose ad- not yet been brought into a solid state, but it mirablc achievements in the liquefaction liquefies at -2970: The critical temperature for of gases have lately been "rendered argon is -- 1860 Fahr., and the critical pressure

amounts to 50o6 atmospheres. popular in this country by Professor 3 From a subsequent communication of BerDewar, has turned some argon which thelot we learn that another sample of argon, also was sent to him by Professor Ramsay from the former. Eighty per cent. of the former

prepared by Mr. Ramsay, behaved quite differently into a liquid at a temperature of 305° combined with benzine, but only six to ten per

cent. of the second would enter into the same 1 This last, the lithium method, has been ex- combination (Comptes Rendus, April 16, 1895, tome perimented upon with success at Nancy, by Guntz cxx., p. 798). Did the former contain so much (Comptes Rendus, April 8, 1895, vol. cxx., p. 777). nitrogen?

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also show two spectra under similar | even would give an additional symconditions ; but Olszewski has found metry to the system. Moreover, Dr. that argon has such a definite temper- Gladstone in this country and Mr. Hill ature of liquefactiou, as well as such a in America have simultaneously indidefinite critical temperature and press-cated in connection with argon a strikure,' that, if it be a mixture, the ing analogy in the growth of the masses mixture must contain but a small pro- of many elements which increase alterportion of another gas. It must also nately by one unit and by three units ; be borne in mind that, under our pres- and a body having an atomic weight of ent knowledge of the spectral analysis, 20 would further confirm this symit remains but an auxiliary to the metry ;8 while Lecoq de Boisbaudran, chemist; it offers one of the means of who also has elaborated a system of preliminary exploration, but any posi- classification of elements, requires in tive decision rests with the regular his turn a body baving an atomic chemical analysis.

weight of a little over 20, and very What, then, is argon, or, at least, the inert, to fill up a gap in his system. gas which prevails in what science All these analogies are of course very already names argon ? From all that interesting ; but in the mean time we has been said it does not appear prob-have no reason to maintain that argon able that it is a chemical compound. really is the required element; the more A compound could hardly have re- so as another hypothesis seems to be sisted so many chemical and electrical much more, or, at least, equally probtests. It has, on the contrary, all the able. behavior of an element; and in such All hitherto obtained argon was concase what is, then, the weight of its taminated by nitrogen, which is lighter atom ? In other words, taking the than argon. Consequently we cannot weight of an hydrogen atom for a unit, be sure that its density is exactly 19:9; what is the corresponding weight for it may exceed 20, and even approach argon ? Its density being twenty times to 21, in which case its molecular the density of hydrogen, we know that weight would be about 42 ; and then its molécule must weigh forty times as argou, in all probability, would be much as an atom of hydrogen ; but for nothing but an allotropic form of nitroargon, as for each new body whose gen. We know indeed that the atmocompounds are not yet known, the sphere contains a varying proportion of difficulty is to decide how many atoms ozone, which is nothing but a conits molecule contaius. If it were built densed form of oxygen grouped in on the same pattern as the molecules molecules of three atoms each (03), of hydrogen, or oxygen and many other while the molecule of common oxygen gases, each of which consists of two contains only two atoms (02). It is atoms locked together, there would be therefore possible that nitrogen, too, no difficulty. We should say that its might appear in two forms : with a atomic weight is 20 (twenty times the triatomic molecule (N,) in argon, and weight of an hydrogen atom), and with the usual biatomic molecule (N2) argon would find a vacant place in the in ordinary nitrogen. This is the

of elements between fluorine hypothesis towards which Mendeléeff, (atomic weight, 19) and sodium (23), Berthelot, and Professor Dewar incline, although it must be said that its in- and various circumstances yield it a ertness would badly clash in this case

? By giving an eighth group (or column) to the with the chemical properties of its second series, which is an “even” series - several next-door neighbors. In the Mende- other even series also having their eighth groups

- and by having certain properties characteristic léeff periodic classification of elements of the eighth groups or columns. it would also find a ready place, and 3 J. H. Gladstone's letter in Nature, February

21, 1895; and E. E. Hill's “ Argon, Prout's Hypoth1 For critical temperatures and pressures see a esis, and the Periodic Law" in American Journal previous “ Recent Science” review (LIVING AGE, of Science, May, 1895, p. 405. No. 2602).

Comptes Rendus, 1895, tome cxx., p. 361.

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certain support, namely, the concurrent appearance of argon and nitrogen The researches were at this point in in nature, the difficulty of separating March last, when another far-reaching them from each other, their inertness, discovery was announced by Professor exaggerated in argon, their common Ramsay. It being known that most lines in the spectra, their double metals and minerals absorb various spectra themselves, and the outer gases which can be extracted from the resemblance between their benzine metal or mineral, it was natural to incompounds in Berthelot's experiments ; quire whether some minerals might not perhaps also the fact that a small contain argon. This was done, and in quantity of argon was found in nitro- the course of his investigations Progen obtained from one of its com- fessor Ramsay was brought to extract pounds.

and to analyze the gas which is conHowever, certain measurements rela- tained in a lately discovered mineral, tive to the heat-absorbing capacity of cleréite, and which was said to be argon - too technical to be discussed in vitrogen. This gas contained a revelathis place

seem to point out that, tion. It proved to be argon, as Mr. under our present conceptions as to the Ramsay expected, but argon mixed arrangement of atoms in molecules, we with some other gas ; and this gas, on ought to consider the molecule of argon spectroscopic examination, displayed, (like the molecule of mercury vapors) among very many other lines, one as consisting of one atom only. In bright yellow line which at once caught this case the weights of both its mole- the attention of the explorers.

It was cule and its atom would be equal to 40. not the well-known yellow line of But not only is there no room for such sodium, but was identified by Mr. a body in the periodical system – the Crookes as another line frequently seen place being already occupied – but in the spectrum of the sun's chromoargon would stand by its chemical sphere, but never obtained before from inertness a unique exception in any terrestrial object. This line, being a classification which indicates the very characteristic of the gases of the chemical properties of every other ele- sun's atmosphere, was ascribed several ment from its position in the system. years ago to some element unknown The periodic law will certainly not be on the earth, but widely spread on thrown overboard to suit this unique the sun, which was therefore named exception ; so that chemists and physi- helium. Now, this element was finally cists may perhaps have to revise their captured in a glass tube in the laborapresent ideas as to the arrangement of tory : atoms in molecules, and to complete One can easily imagine the sensation them by introducing into molecular produced by the announcement of this structure the conception of chemical discovery. Many chemists had for energy. Who knows whether the con- years searched for helium among the tradiction displayed by argon will not substances which exist on the earth be an impulse to the appearance of and in meteorites fallen from the celessome epoch-making work on the struc-tial spaces, but in vain ; while now ture of matter ? ?

the longed-for yellow line glittered in

the spectroscope, quite unexpectedly, 1 Lord Rayleigh and Mr. Ramsay explain this originating from a by-produce discovlast circumstance by the fact that in the manipu-ered in the search for argon! Upon lation of the gases large quantities of water were used, and water freely dissolves argon ; to which the reception of the welcome news, the Mendeléeff very justly remarks that this is un

Upsala Professor Cleve (in whose doubtedly very possible, but has to be proved. See Lord Rayleigh's objections to this hypothesis the law, but in an opposite direction. (See Menin his Royal Institution lecture (Nature, June 13, deléeff's note on argon, 1.c.) 1895).

: Communication made to the Chemical Society : It is well worth noticing that the case of argon at its anniversary meeting (Nature, April 4, 1895, is opposed to the case of chlorine, which is chem- vol. li., p. 543, lii., p. 7; Proceedings of the Royal ically a most active body, and also deviates from Society, April 25).

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honor Nordenskjöld had named the learned from Professor Ramsay that,
mineral) at once extracted the new while boiling clevéite in weak sul-
gases, and Thalén, one of the best phuric acid, he obtained not only the
spectroscopists of our time, fully con- gas supposed to be helium, but also
firmed Mr. Crookes's statement. The argon devoid of some gas which is
gas obtained at Upsala showed the usually found in atmospheric argon,
same yellow line, but it contained no and which may be the cause of the
trace of argon; and Cleve at once high density of the latter. Three or
ascertained that it was of a very four distinct gases have thus been
low density. This was confirmed by discovered - or rather preliminarily
subsequent experiments, and the last pointed out by the spectroscope
news from Upsala is to the effect that while several more are already in
Cleve's helium bas only 2.02 times the view.
density of hydrogen, so that its atomic We thus stand on the threshold of
weight must be either four or two. most important discoveries which are
The Upsala gas would thus come into sure to throw much light on the chem-
the wide gap existing in our lists of ical processes going on on the surfaces
elements between hydrogen, whose of the celestial bodies, and certainly
atomic weight is taken for a unit, and will endow the physics of the sun and
lithium, whose atom is seven times the stars with important generaliza-
heavier than the atom of hydrogen.1 tions; while on the other side the dis-
On the other side, Mr. Lockyer has covery of one or perhaps two gases,
obtained the new gas by another possessed of low atomic weights, which
method, from another mineral of the have hitherto been vainly sought for,
same group, bröggerite ; it was asso- will undoubtedly free our chemical
ciated with hydrogen, but, like Cleve's classification from an incertitude which
gas, contained no argon. The same has prevailed till now. And, finally,
brilliant yellow line of helium shines in the heoretical questions arising from
the spectrum of the bröggerite gas, in the properties of argon, and even from
company with several other lines the very errors which may have been
which were known in the spectrum made during the earlier hypothetical
of the sun's chromosphere, but had period of discussion, are sure to launch
never been seen before in the spectra physics and chemistry in a new domain
of terrestrial objects. It appears, of philosophical speculation.

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This moreover, from a second and third mass of discoveries, rapidly following communication of Mr. Lockyer to the each other, may seem bewildering; Royal Society 8 that he has found but they were not unexpected. For traces of other solar gases mixed with years chemistry had cautiously perhelium, and that he expects to obtain fected its methods, and minutely acby bis method quite a series of gases, cumulated new data in a limited circle the spectral lines of which are asso- of facts. Now, the fruits of that ciated with the spectral lines of the laborious work are rapidly ripening. chromosphere. At the same date we “ Are we facing a new period in

chemistry ?” Cleve exclaimed at the 1 Mr. Ramsay has found that his gas (obtained from a mixture with argon) has a density of 3-89, end of a letter in which he announced and the same monatomic structure as argon, or at his discovery. Undoubtedly we are least the same ratio of specific heats.

our : Proceedings of the Royal Society, April 25, knowledge of facts and our theoretical

entering a period when both 1895; Nature, May 2, 1895, vol. lii., p. 8. 3 Nature, May 10, 1895, vol. lii., p. 56.

views in chemistry will be immensely • The fact of several chromosphere lines being widened. seen at the same time is the more important, as Professor C. Runge, armed with one of the best the contradiction between such authorities in specspectroscopes, maintains (in a letter dated May 16, troscopy as Runge, Crookes, Lockyer, and Thalen and published in Nature, June 6, 1896) that the has not been explained in the press; but the conyellow line obtained from clevéite is not at all the current appearance of several chromospheric lines helium line, but consists of two lines situated on leaves little doubt as to discovery of gases which both sides of the latter, Up to this date (June 19) prevail in the atmosphere of the sun.

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III.

a subject of controversy for the last We live in an atmosphere which is seventy years ; but it is only now that loaded with electricity. When heavy our ideas upon the whole subject begin storm-clouds obscure the sky, and, tak- to take a definite shape. ing those yellowish tints which are A few years ago,

two Austrian characteristic of electrified vapors, meteorologists, Elster and Geitel, insend towards the earth immense sparks tending to study the distribution of of lightning, the electricity in the at- electricity in the atmosphere at differmosphere becomes visible. We may ent heights, inaugurated a series of also collect it in the way Franklin and simultaneous measurements, at the Buffon used to collect it, by means of observatory which is planted on the kites launched high in the air, and top of the Sonnblick (a high peak of study it in the laboratory. Again, the Tyroleau Alps), and in a valley at when cold weather sets in over the dry the foot of the peak. They had, howplateaus of Siberia or America, the air ever, to realize to their regret that becomes so permeated with electricity their comparative measurements were that a fur coat, thrown off in the a failure, because a waterfall which obscurity, glitters with crepitating runs in the valley so much electrified sparks. But even in cloudless weather the air around it, up to an altitude of in western Europe, if the naturalist sixteen hundred feet, that no compariwalks about with a portable electrom- son was possible between the low-level eter, and measures the density of and the high-level observations. This electricity in the air, as Lord Kelvin unsuccess brought the question as to did many years ago, when he repeated the electrifying powers of waterfalls Pouillet's experiments on the sea- again to the front, and Herr Lenard beach of the Island of Arran, the con- undertook a series of observations on tinual changes in the instrument's their electrical effects in Switzerland.1 indications will show that masses of It appeared that, to say nothing of highly electrified air are continually large waterfalls, even the small ones, wafted along by the gentle breezes at a few feet high, send into the air cona certain height, and thus transport siderable charges of electricity, proand distribute electricity in the at- vided they bring down a large amount mosphere. And, finally, the electrom- of rapidly dashing water. The smalleters which have been installed at est jets of water, which drip on the many observatories — partly with the rock sides, and even roaring streamlets, hope that their indications would be have the same effect ; while above the of some help in the prediction of local surfaces of quiet lakes no electrification storms and rains - show that at every of the air was detected, notwithstandmonent of the day the charge of elec- ing the constantly going on of evaptricity contained in the atmosphere is oration. In further prosecuting his changing, so that even at two spots researches, Lenard came to the consituated near to each other the indica- clusion that the current theory which tions of the instruments may vary in explains electrification in the neighborthe most capricious way.

hood of waterfalls by the inductive That the electricity which we find in action of the positive electricity which the atmosphere may originate from is usually spread in the air during fine various sources - from the evaporation weather, is not supported by observaof water which is continually going on tion. He also remarked that neither on the earth's surface, from the un- evaporation nor the mere rushing of equal heating of superposed strata of water drops through the air would exair, from vegetation, and even from plain the phenomena, and that the chemical changes which go on on the chief cause of electrification of the air surface of the earth was pointed out is the tearing asunder of the drops of long since ; and the relative importance 1 Wiedemann's Annalen der Physik, 1892, Bd, of these different causes has remained | xlvi., p. 584 sq.

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