SCIENCE NOTES,

Otago Witness, Issue 2355, 13 April 1899, Page 54

SCIENCE NOTES,

*" — I — If we place over water, under a glass bell containing nitrogen aud carbonic acid a green • plant— for example, the Lysimachia nummu- I faria — the presence of oxygen Boon is present in the bell, and at the end of several months its contents are more rich in this gas than ie the outside air. The Agaricus atramentarius, on the contrary, gives us an example of a plant formed of aerobic cellules, whioh cannot vegetate without oxygen and . which can analyse the air as completely as » eliok of phosphorus would do it. Thus, if ! we place over water, in a graduated glass full of air, composed of oxygen and nitrogen, on« of these mushrooms, avoiding direct contact with the water 'and exposing it to the sunlight, we shall presently remark an abundant condensation of water, and then all the oxygen is absorbed. The carbonic acid-pro-duced being dissolved by the water, the latter rises in the glass. In a glass on a capacity ot 200 cubic centimetres (15 cubic inches) the level of the' water in "a few days rises 160 centimetres and then remains stationary. The glass then contains nothing but nitrogen ; the mushroom dries up and may_ be preserved in this shape, all growth having ceased. In fact, it is mummified in nitrogen. If now we introduce near the agaric a green plant, such as the Lysimachia already mentioned, we •hall perceive, after several days, that the mushroom begins again to grow slowly; but a* the green plant produces more oxygen than the mushroom can use, the- level of the water Boon descends. Mr D. T. L. Phipson, who relates these experiments in the Chemical News, concludes from them thatnhe vegetation of green plants in nitrogen containing a -little carbonic acid proves that they are essentially anaerobic, -Ihat they can prosper without oxygen, and that they are the means employed by nature to furnish our atmosphere with this gas. He believes that the air has thus changed in the course of centuries, becoming more and more oxygenated, which has enabled aerobic plants and animals to make

their appearance —An original idea was mooted some months ago in Paris by M. Felix Dubois, an explorer who has accomplished some goocl work, and whoso account of his journey to Timbuctoo has appeared in English guise. He suggested that the solution of the problems of locomotion and communication in new centres was to be found in the.motor car The notion aroused no little amusement, and ' was seized by the comic papers, but already there is ample evidence .that the idea is far more practical than seemed to be the case at first sight. M. Felix Dubois (says a correBpondont) is putting hie scheme in practice in the Soudan with excellent results. He has imported two motore cars — an omnibus and a dray — to-Kayea, and the experiments with them in the surrounding districi are said to have been exceedingly successful. In any case, the two cars have covered the 600 kilometres between Kayes and Bamakou, although the carriage road that is to connect ( these two places is not ret completed.' But

this is not all. M. Felix Dubois's idea is to bo turned to account in Madagascar at once on a very considerable scale. General Gallieni has just signed a contract with a French firm, who have undertaken to effect the transports between Mahatsara and T^anaraive. It is not expressly stipulated that motor cars shall be employed, but it is the intention of the firm to utilise them, and to encourage them to do bo a clause in the contract binds the Government to accord them certain financial advantages if they have recourse to this mode of transport. — Most people think that it rains more in winter than in summer, while the contrary is really the case. The reason of the popular error is, of course, that the ground is much wetter, and the streets arc far muddier in the former season than they are in the latter. But meteorologists, who found out the true state of affairs by means of their rain-gauges, are ready with an explanation. In winter, the days are short, the amount of sunshine we get is very small, and the air is cold. Hence we have an atmoephere nearly all the time as full a? it can be of moisture, and whatever rain falls remains on the ground. But in summer, the warm air and bright sunshine take up the water very quickly from the ground and leave it dry. And as we judge of the rainfall more by the state of the ground than by the actual fall of water, we have taken hold of quite an error with regard to seaponaii rainfall. — Telegrams from Airolo state that the St. Gothard Tunnel is threatened with destruction, as an enormous boulder from the Sasso Rosso ip on the point of rolling down the mountain side, not only threatening to obstruct the entrance to the tunnel, but also placing the village of Airolo in serious danger. A vigilance committee has been appointed, which will announce any sign of danger by firing a cannon. Steps have been taken to warn the St. Gothard express in time, the employees on the line having been doubled. — Some further information about nitragin has been brought recently before the Royal Society. The parasitic nature of both the filsments and bacteroids contained in the nodules found upon the roots of leguminous

plants is confirmed. It will be remembered that these bodies possess the property of fixing atmospheric nitrogen, and so enabling it to be assimilated by the leguminous plant upon the roots of which the uodules are formed, thus giving to such crops the distinct advantage of not requiring expensive nitrogenous manures for their growth. Nitra•gin, which is a commercial preparation containing these bodies, has fc»e<> examined, and it has been found that a supply o: it to a soil poor in nitrates results in an incensed yield, though better results are said to be obtained if, instead of nitragin, nitrates be added to th-a soil.

THE DISTANCES OF THE STARS.

The nearest star is so far from us, Professor Todd says in his "New Astronomy," Eublished by Sampson Low — one of the best ooks of the kind that we have seen — that its distance in figures, however expressed, remains unapprehended by the human mind.

"Who can conceive of 25 millions of millions of miles? Yet so remote is our closest stellar neighbour: — "To realise in some sense the enormous distance of the -nearest fixed star from our earth, open a Webster's International Dictionary, which contains over 2000 pages of three columns each, or the equivalent. Begin to read as rapidly as you can, and imagine a ray of light to have just left the neare3t fixed star at the instant you begin. By the time you have finished a single page the stoi-'s light will have sped on towards ths enrrh no less than 100,000,000 miles, imagine that you could keep right on reading, tirelessly and without ceasing cUy and night, just as light itself travels — how many pages would you havo read when the ray of light from Aipha Centauri, the nearest fixed star, had reached the earth? You would have read it completely through — not once or twice, but nearly a hundred timei."

So enormou&ly distanc, indeed, is this nearest of the stars that if it were blotted out of existence this present moment it would continue to shine in its accustomed place for more than three years to come !

THE PAST AND FUTUBF OF THE STTN.

The chapters dealing with the sun are particularly interesting. As to the past and future -of that luminary we aro told that, accepting the theory that the sun's heat is maintained by gradual shrinkage- of his volume, he must have been vastly larger in the irmote past, and he will become very much reduced in size in the distant future : "If wo amune the late of contraction to remain unchanged through indefinite ages it is possible to calculate that the earth has been receiving heat from the sun about 20,000,000 years in the past; also that in the next 5,000,000 years ho will have shrunk to onehalf his present diameter. For 5.000,000 years additional he might continue to emit heat sufficient to maintain certain types of life on tho earth. A vast period of 30,000,000 to 40,000,000 years, then, may be regarded as the likely duration, or life period, of the solar system, from origin to end." Their heat all lost by radiation, the sun and his family of planets might continue their journey through interstellar space as inert matter for additional and indefinite millions of years.

OTHER UNIVE3SKS Tll\y OUKS

There are, of course, stars immensely remote from the solar system in all directions, and everywhere scattered among myriads remoter still, whose distances there seems ho proppect of ever ascertaining. What is beyond?—" Outside the realm of the fact imagination alone can answer. We cannot think of space except as unlimited. The concept of infinite spßoe precludes all possibility of a boundary. But the number of stars visible with our largest telescopes is far from infinite ; for w e should greatly overestimate their number in allowing but ten stars to every human being alivo this moment upon our little planet. Are, then, the inconceivable vastness of space tenanted with other universes than the "one o*r telescopes unfold? We are driven to conclude that in all probability they are. Just as our planetary system is everywhere surrounded by a roomy starles3 void, so doubtless our huge sidereal- cluster rests deeu in an outer space everywhere enveloping inimitably. So remote must be these external galaxies that ur.extinguished light from them, although it speeds eight times round the earth in a single second, cannot reach us in millions of years. ' Verily " infinite space transcends apprehension by finite intelligence," as Professor Todd remarks. The "New Astronomy" is fully illustrated, beautifully printed, and is altogether attractive and useful.