-

thousand feet high, of the Tyrolese Alps | maps of monthly isobars and prevailing winds, they were quite a revelation, even though the data upon which they were based were very incomplete at that time.2 But better data have been collected since, and in the hands of Mr. Buchan they have undergone such a careful and able analysis that the

as well as from observations made on several other high-level stations, he has concluded that a cyclone cau not be due to a local heating of the earth's surface and to an ascending current of warm air provoked by this cause, just as an anti-cyclone cannot be due to a local cooling of the earth's surface, and to a consequent condensation of the air. Contrary to the previsions of the meteorologists, the ascending column of air within a cyclone, up to a height of some ten thousand feet, is not warmer than the surrounding air; it is cooler within the cyclone, and its upward motion thus cannot be due to its temperature. So also in an anti-cyclone the descending current of air is warmer than it is under normal conditions, and its downward motion must be due to some other cause than an increase of density resulting from a lowering of its temperature. The decrease of pressure in the one case, and its increase in the other, thus cannot be caused by differences of heating or cooling of the lower strata; and both cyclones and anti-east Asia and North America act in cyclones must be considered as parts of the general circulation of the atmosphere, such as it was conceived by Ferrel.1

Challenger Reports" charts may be taken as the best reliable representation of the winds, the temperatures, and the pressure in the lowest strata of the atmosphere, as well as the surest basis for further generalizations. The theories which have been mentioned in the preceding pages give the grand lines of atmospheric circulation; on Buchan's maps we see how the grand lines are modified in the lowest strata by the distribution of land and sea, and the unequal heating or cooling of continents and oceans. The leading features indicated by theory are still maintained, and they become even still more apparent if we consult isobars. traced for a certain height, like those of Teisserenc du Bort; but the immense plateaux of

winter as colossal refrigerators, where cold and heavy air accumulates, to flow down in all directions towards the lowlands. We see also how in July the air is heated in the lower lands of northwest India, in the corner between the Afghanistan and the Tibet plateau, how

Such a deep modification of the current views, though supported to a great extent by weighty evidence, will obviously not be accepted without opposi-pressure is lowered there by the astion; but it is already making its way, and certainly will exercise a deep influon the further development of meteorology.

ence

cending current, and how winds blow

2 To trace the isobars, or lines of equal atmospheric pressure, reduced to the sea-level, the real' altitude of each meteorological observatory must in 1869 the altitude of not one single station in be known from direct geometrical levellings; but siberia, central Asia, or even the Urals was known. A levelling across Siberia, as far as Lake Baikai,

has been made since, Mr. Buchan's isobars having

been one of our best arguments to press the necessity of the levelling. But Mr. Buchan may not be

Abandoning now the domain of theoretical investigation, I must mention a work also a life's work which may safely be placed side by side with the best achievements in theory. I mean the beautiful charts of Mr. Buchan, rep-aware that the levelling beyond the ninetieth deresenting the distribution of pressure, temperature, and winds over the surface of the globe, embodied in the last volume of the " Challenger Expedition Reports." When Mr. Buchan published, twenty-three years ago, his first

1 See the discussion of this subject between Hazen and J. Hann in Science, 1890. xv. 382-384, and "Meteorologische Zeitschrift," 1890, p. 328.

geodesists as utterly unreliable; it is supposed to contain some substantial error, so that a new levelling between Krasnoyarsk and Lake Baikal is insisted upon. The incertitude in the isobars on an immense space in north-east Asia resulting

gree of longitude is now considered by Russian

from this cause may attain as much as one or, perhaps, even three tenths of an inch.

3 An excellent résumé of the whole work and its results in a popular form has been published by Buchan himself in the "Proceedings of the Geographical Society," March, 1891.

known that a black powder, composed of transparent microscopical crystals having the hardness of diamond, is deposited on the negative electrode when a weak galvanic current is passed through liquid chloride of carbon. But these crystals, like those of Mr. Marsden, belong to the easily obtained variety of black diamonds known as carbonados; while some of the crystals obtained by Moissan are real colorless and crystallized diamonds the gem we all know and admire.

towards this region of lowered pressure. | tained black carbon crystals with curved We see more than that: on looking on edges. Besides, it was generally the maps it strikes the eye how the moisture or the dryness of the climate is dependent upon the distribution of pressure, and how the dry anti-cyclonic winds make barren deserts of parts of North and South America, of Africa, and central Asia, and how they will continue to dry the lakes and the rivers of these regions and occasion total failures of crops so long as that distribution of pressure lasts on the globe, and man has not yet learned to eschew its effects by getting water from the depths of the earth. The life of the globe during the present period is written on these splendid charts.

II.

For industry and every-day life the infinitesimal quantities of diamond dust obtained by the French chemist may have no immediate value, and some time will probably be required before a modest-sized jewel is made in a laboratory. But the discovery has a great scientific interest, inasmuch as it is the outcome of a whole series of researches which have recently been made with the view of artificially reproducing all sorts of minerals and rocks, and which are admirably chosen for ultimately throwing new light upon the intimate structure of physical bodies.

AT one of the recent sittings of the French Academy of Sciences, Henri Moissan, whose name has lately been prominent in chemistry, in connection with several important discoveries, read a communication to the effect that he had finally succeeded in obtaining in his laboratory minute crystals of diamonds. His communication was followed by a paper by Friedel, who has been working for some time past in the same direction, and has attained simi- Moissan's method is based upon the lar though not yet quite definite re- capacity of iron of absorbing carbon at sults; and, finally, Berthelot, who also a high temperature and of giving it was working in the same field, but fol- back in the shape of grains and cryslowed a different track, announced tals while the iron mass is cooling. that, in view of the excellent results When iron has been saturated with obtained by Moissan, he abandons his carbon at a temperature of about two own researches and congratulates his thousand Fahrenheit degrees, a mixcolleague upon his remarkable discov-ture of amorphous carbon and graphite

cry.

The discovery is not absolutely new, and the French chemist himself mentions two of his English predecessors. Mr. Hannay obtained in 1880 some diamond-like crystals by heating in an iron tube, under high pressure, a mixture of paraffin oil with lamp-black, bone oil, and some lithium; 2 and in the same year Mr. Sidney Marsden, by heating some silver with sugar charcoal, ob

1 Comptes Rendus de l'Académie des Sciences, February 6, 1893, tome cxvi., p. 218.

2 Proceedings of the Royal Society, xxx. 188; quoted by Moissan.

is discovered in the iron mass. At higher temperatures the fused iron dissolves more and more carbon, and the cast-iron of our blasting furnaces, after having been heated to about three thousand degrees and slowly cooled down, contains, as known, an abundance of graphite crystals. It was thus natural to see whether a still higher temperature, and cooling under high pressure, might not give the still denser form of carbon - that is, the diamonds.

In order to thoroughly saturate iron

3 Proceedings of the Royal Society of Edinburgh, 1880, ii. 20 (Moissan's quotation).

Mr. Marsden's experiment with silver was also repeated; but silver being a bad dissolvent for carbon, even at high

with carbon at a high temperature, and | them proved to be real diamonds; they to cool it under a high pressure, Mois- were translucent, they scratched a san resorted to a very simple and effec- ruby, and they distinctly showed under tive means. He took a hollow cylinder the microscope the crystalline structure of soft iron, filled it with some purified and cleavage of the diamond; their sugar charcoal, and corked the cylinder density was that of the precious gem, with an iron screw. Then about half a and they were completely consumed in pound of soft iron was molten in a cru- oxygen at a temperature of 1,800 decible in Moissan's new electric furnace, grees.1 which readily gives a temperature of about three thousand Centigrade degrees (5,400° Fahrenheit), and the cylinder was plunged into the molten temperature, it was boiled for some metal; iron was thus thoroughly sat- time with sugar charcoal in the fururated with carbon. The crucible was nace, the cooling being operated in the then taken out of the furnace and same way as with iron. The result plunged into a pail of cold water until was extremely interesting. No diathe surface of the iron mass was cooled to a dull red temperature, whereupon it was taken out and left to cool in the air. This was the ingenious means of obtaining a high pressure. It is known that water when it becomes ice increases in volume, and that if it freezes in a strong shell the interior pressure of the crystallizing water often bursts the shell; but if it cannot burst the shell it necessarily solidifies under an immense pressure, due to the molecular forces. The same was done by Moissan with the liquid iron, which also has the property of increasing in volume while it solidifies. An outer solid crust having been formed by a sudden immersion into cold water, the crust prevents the further expansion of the iron mass, which is thus bound to solidify under an immense pressure, like the water in the shell.

monds were obtained, but a series of carbonados of different densities (from 2.5 to 3-5 times heavier than water) were discovered, some of them in grains, some others in needles, or in conchoidal masses, the densest ones also scratching ruby and burning in oxygen at 1,800°. This is perhaps the most interesting part of Moissan's researches, as it confirms the long-since suspected fact that there is a whole series of carbon molecules each of which is composed of a different number of atoms, and some of which must be very complex.

As to the quantities of diamond dust obtained in this way, they were extremely small. Several cylinders gave no diamonds at all, and from all his experiments Moissan could not collect even a few milligrammes (a few hundredth parts of a grain) of the precious dust, although the black carbonados were quite common. But a sure method is now indicated, and its further development is only a matter of time and perseverance.

The scientific value of these

re

The next step was to separate the iron from the carbon crystals which it might contain. This was done by dissolving the iron in hydrochloric acid, and three different varieties of carbon crystals (which are not attacked by the acid) were received as a residue. Some searches is undoubtedly very great. graphite, some chestnut-colored, curved Diamond, like graphite and simple needles of carbon, and diamond dust charcoal, is pure carbon, but all atcould be seen; and they were separated tempts at fusing carbon or dissolving from each other by several complex it have hitherto failed; it could not be operations indicated by Berthelot in brought into a liquid condition out of one of his previous works. A few which it afterwards might crystallize. grains of diamond dust were finally obtained-most of them belonging to we learn that the same varieties are found in the the carbonado variety, while a few of diamond-bearing earth at the Cape.

1 From a subsequent communication by Moissan

However, the investigations recently | months at a temperature of nearly one made into the carburization of iron, thousand degrees. The importance of especially by Roberts Austen, tended a high temperature for further achieveto prove that in steel and cast-iron the ments was rendered still more evident carbon is not simply diffused through in Frémy's successful reproduction of the iron, but enters with it into some of the ruby. The ruby is, of course, quite those combinations in definite propor- different from the diamond. Like the tions which, like all solutions, occupy sapphire and the corundum, it is nothan intermediate position between realing but alumina, that is, a compound of chemical compounds and purely physical two atoms of aluminium with three mixtures. It was reasonable, there- atoms of oxygen, colored by some imfore, to presume that carbon is brought purities in red, in blue, or in brown. into a liquid condition in molten iron, But for a long time alumina would not and that under certain conditions it crystallize in our laboratories. Later may crystallize in the shape of dia- on Frémy obtained a very fine dust of monds within an iron mass. Moissan's rubies; but when he submitted the discovery confirms this view. On the constituent parts of the ruby to a temother side, the researches of Moissan perature of 2,700°, and maintained the and Friedel must also throw some light same temperature for one hundred conupon the great questions raised by Men-secutive hours, he was rewarded by deléeff as regards the probable pres-full-sized crystals of the precious stone, ence and prevalence of iron and carbon big enough and in sufficient numbers compounds in the interior of the globe, to have a collar made of them. And the formation of naphtha out of these compounds, and other extremely interesting geological questions.2.

finally, the investigations of Friedel, Le Chatelier, and especially F. Fouqué and Michel Levy, who reproduced a The artificial reproduction of the dia- micaceous trachyte containing felspar, mond must also be viewed as a further spinel, and mica, demonstrated the step in a long succession of researches necessity of resorting to a high pressure which have been lately pursued for arti- in addition to a high temperature. ficially reproducing all sorts of minerals, To extend the range of high temperathe formation of which had long re-tures hitherto obtained, and to devise a mained a puzzle for mineralogists. The means of measuring them, was thus silicates which were formerly consid- the first condition for further progress ered as impossible to reproduce in the in the reproduction of minerals and laboratory have yielded within the last gems. But the measurement of high few years before the efforts of the temperatures is a very difficult problem chemists. Sarrasin, Hautefeuille, and which has much occupied of late sevespecially Friedel, have reproduced dif- eral prominent physicists and chemists. ferent varieties of the chief constituent A thermo-electric thermometer, made mineral of our crystalline rocks-fel- of two very resistant metals (platinumr spar- and the artificial crystals are and an alloy of platinum with rhodium), absolutely identical with those found in and graduated with the aid of the air nature. Hornblende, which had long thermometer, finally came into general defied the efforts of the explorers, has use, and it proved to be quite reliable been finally obtained in 1891 by K. - but only up to three thousand FahrenChrustchoff, after he had spent seven heit degrees, which temperature was years in unsuccessful attempts; but soon surpassed. Then, Le Chatelier in order to reproduce it he had to heat devised a pyrometer based on the variaits constituent elements for three tions of intensity of light of fused metals at different temperatures, and

8

4

1 See "Recent Science" in LIVING AGE, No. this instrument again proved to be suf2505, p. 3.

2 See, in Mendeléeff's "Principles of Chemistry," the footnotes to the chapters on carbon and iron. 3 Comptes Rendus, 1891, t. 112.

4 C. Barus, in Philosophical Magazine, 5th series, xxxiv. 376; L. Holborn and W. Wien in Wiedemann's Annalen, xlvii. 107.

ficiently accurate up to thirty-six hun- | low temperatures of about two hundred dred degrees; but this last temperature, Centigrade degrees below the freezingtoo, is now surpassed by Moissan, by point. means of his new electric furnace, And, finally, Moissan's discovery eswhich is a real model of efficiency and tablishes a new link between the simplicity. It consists of two super-processes which we obtain in our labposed bricks, made of quicklime, or of an especially pure calcinated magnesia. A groove with a small cavity in its middle (large enough to receive a small crucible) is made on the upper face of the lower brick in the sense of its length; and two carbon electrodes are introduced from both sides into the groove. As soon as they are connected with a dynamo-machine the electric arc appears between their extremities, and an immensely high temperature is produced in the cavity. Thus, a small Edison machine, worked by a gas-engine of eight horse-power, gave a temperature estimated at about forty-five hundred Fahrenheit degrees, and with a fifty horse-power engine the enormous temperature of about fifty-four hundred degrees (3,000 Centigrade) was reached.

The effects of this little furnace are

oratories, and those which are going on in the celestial spaces, in the formation of meteorites. It was known long since that these masses of silicates and nickelled iron which travel in the interplanetary spaces and, entering occasionally into the sphere of attraction of the earth, fall upon its surface, sometimes contain charcoal or a special variety of graphite; but later on, in 1887, the St. Petersburg professors Latchinoff and Eroféeff went a step further and proved that the charcoal is occasionally transformed into diamonds; thus they extracted some diamond dust from the meteorite fallen during the previous year at Novo Urei, in the province of Penza. Some doubts were, however, entertained as regards their discovery, but the fact has been fully confirmed since by Friedel and Le Bel, who found in a meteorite from Cañon Diablo minute diamonds and carbonados, exactly similar to those of Moissan.2

simply wonderful. At about 4,500° lime, strontia, and magnesia are crystallized in a few minutes. At 5,400° It is thus evident that the artificial the very substance of the bricks is fused reproduction of the diamond is not one and flows like water. Oxides of vari- of those accidental discoveries which ous metals which were considered as may be made without leaving an imquite irreducible are deprived of their pression upon science for many years oxygen in no time; nickel, cobalt, man- to come. It is only one of the many ganese, and chrome oxides can be re- advances made in a certain direction, duced at a lecture experiment, and and is the outcome of the whole drift a piece of one hundred and twenty of modern research which endeavors grammes of pure uranium is obtained immensely to widen the means at our at once from the uranium oxide. At disposal for effecting physical and chemabout 4,050° pure alumina is fused and ical transformations of matter. It is little rubies are formed; true, they are one step more into a new domain where less beautiful than those of Frémy, but chemistry, metallurgy, and mineralogy the whole experiment lasts less than a join hands together for revealing by quarter of an hour. At a higher tem-joint efforts the secrets of the conperature alumina is even volatilized, structive forces of matter. and nothing is left of it in the crucible. In short, the results are as interesting and as promising as those which Pictet and Dewar have witnessed when they went to the other end of the thermometric scale and produced the extremely

1 Comptes Rendus, December 12, 1892, t. cxv.

III.

THE study of the direct action of environment upon organisms, and of the mechanism of its action, becomes a favorite study among biologists — the

2 Comptes Rendus, December 12, 1892, t. 115, p. 1039; also February 13, 1893.