They had been floated from far away the frontier of Austria. But her days near the upper Oder, and were going of greatness are past. to Hamburg, in order to be there loaded Before the skipper's wife had made on steamers bound for England, for ready my soup, I had passed barges this wood is used in the mines. Next enough to fill a page of statistics; but year these cargoes will be made up in figures are notoriously fallacious, as Stettin, and not Hamburg. All north every statistician knows. The good Germany needs coal to a vast extent skipper kept pointing out barge after for the factories that have grown up barge from points in Germany whose along her inland waterways. Ham- geographical situation made it clear burg has been the chief depot for this that soon these waters would see them commodity not merely in supplying no more. The cholera gave Hamburg the towns along the Elbe, but Berlin, a sharp blow, but the sharper one is Breslau, and beyond. Henceforward that involved in declaring open the sea-going colliers will bring their loads waterway between the North Sea and to ports on the Baltic, such as Memel, the Baltic. Yesterday Hamburg was Königsberg, Elbing, Dantzig, Stettin, facile princeps the commercial harbor Rostock, Lübeck. of Germany; to-morrow she begins a

In other words, Hamburg to-day decline, slow but distinct. She will ceases to be the nearest port to the soon be known for the ruins of her great centres of German consumption. picturesque warehouses, the excelShe will remain the first seaport of lence of her eating-houses, the VeneGermany by reason of the excellence tian-like beauty of her thoroughfares, of her harbor, and the fact that she is the Venetian-like character of her hisat the mouth of a river which carries tory. On her epitaph we shall read: barges from the North Sea to beyond "Killed by the Baltic Canal." POULTNEY BIGELOW.

A MOTH-CATCHING PLANT.- This plant, | for its sweet juices is placed at its base. (Araugia albens), which is a native of Attracted by the powerful scent and the southern Africa, was introduced to New Zealand quite accidentally about seven years ago, and since then it has been extensively propagated there, on account of its effective service as a killer of destructive moths. Wherever the climate is mild, the plant is an exceedingly free grower; it twines and climbs with great luxuriance, and produces immense numbers of white or pinkish flowers, which have a very agreeable scent. These flowers attract innumerable moths. On a summer evening a hedge of araugias will be covered by a perfect cloud of moths, and in the morning there will not be a single flower that does not imprison one or two, and sometimes as many as four insects of various sizes and genera. The action of the araugia is purely mechanical. The calyx of the flower is rather deep, and the receptacle

prospect of honey, the moth dives down the calyx, and protrudes its proboscis to reach the tempting food. But before it can do so the proboscis is nipped between two strong, hard, black pincers, which guard the passage, and once nipped there is no escape for the moth, which is held as in a vice, by the extreme end of the proboscis, and dies miserably. The rationale of the process is not yet explained. A plant of araugia, covering a space of ten yards in length, will destroy as many hundred moths every night, and, consequently, prevent the ravages of fifty times as many larvæ. It is, however, a singular fact that in New Zealand, where the plant has often been cultivated for the express purpose of destroying the detested codlin moth (Carpocapsa pomenalla), that wily insect declines to enter the trap.

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From The Nineteenth Century.
RECENT SCIENCE.

BY PRINCE KROPOTKIN.

I.

Is it an element which, like hydrogen or oxygen, cannot be decomposed into still simpler bodies-a "chemical individuality," as Mendeléeff says,

No substance in nature seemed to be which maintains its individual characbetter known to chemists than atmo-ter even when it combines with other spheric air. The composition of air individualities? Or is argon a mixture taken from the most different localities of several new elements? Or is it a and altitudes had so often been an- compound of well-known elements alyzed by the best chemists and physi- which were never met before in that cists that up to the last few years it special combination? These questions seemed almost inadmissible that any press themselves upon every one's gas existing in the atmosphere should mind. However, up to the present date have escaped detection. However, they have not been answered, and most modern chemistry disposes of such per- probably the answer will not be given fect methods of analysis, and our for some time to come, not only bemodern laboratories are supplied with cause the discovery of argon was immesuch wonderfully precise instruments diately followed by the discovery of - it is sufficient to say that in a modern several other gases, but also because weighing the incertitude is inferior to argon is so peculiar in its behavior as one fifty-thousandth part of one ounce to raise a host of questions of para- that when the study of air and other mount importance for chemistry. The gases was again taken in hand with general reader, accustomed to get from the aid of the new instruments and science ready results, may therefore methods, a vague suspicion began to feel disappointed when, after having grow up. "After all," it was said perused the following pages, he only in scientific circles, " atmospheric air finds a number of new unsolved probis not so very well known," and it lems cast upon science. But, to follow possibly may contain small quantities step by step the inquiry which is now of some unknown gases mixed with its going on, to share the hopes and the principal components - nitrogen and doubts of the explorers, and thus to be oxygen, carbonic acid, and vapor of initiated into the mysteries of scientific water.1 These suspicions are now research itself, and into the methods fully confirmed. When the researches of discovery of scientific laws, is perof Lord Rayleigh and Professor Ramsay haps even more interesting, and cerwere published in full, it became evi- tainly much more suggestive, than to dent that atmospheric air contains over learn some time later the bare reone-half per cent. of some gas (or sults. maybe gases) formerly unknown, and that this gasnamed argon by its discoverers is possessed of chemical properties which offer many a puzzle to the chemist. The distrust which the announcement of the discovery was met with in August last has been dissipated since, and the question, What argon is? stands now foremost.

-

For the last seven years Lord Rayleigh has been engaged in remeasuring the densities of the commonest gases, with all the precision obtainable from modern appliances, and his work was soon recognized to be a standard work. However, even in the earlier stages of his researches, while he dealt with oxygen and air, there appeared certain 1 Mendeléeff, in his "Principles of Chemistry" discrepancies between his otherwise (English Edition, vol. i., p. 226, note 12), already most accurate results, which, precisely expressed the opinion that, under the electrical because the measurements were discharge, the nitrogen of the air may be partially dissociated, giving origin to monatomic molecules perfect, could not well be explained by (N). Helmholtz, having received the news of the unavoidable errors, and created a cerdiscovery of a new constituent of the atmosphere, tain uneasiness as to the permanence said that he always thought "that there was some

thing more in the atmosphere" (Lord Rayleigh's of the constitution of air. But when lecture on argon at the Royal Institution). he came later on to deal with nitrogen,

things took a more serious aspect. | physicist and the chemist, working first Nitrogen is an element; and, whether separately, made the necessary arrangeit be obtained from the air or from ments for isolating the new heavier one of the nitrogen compounds, such gas by two different methods. They as ammonia, it must always be the obtained it, nearly pure, and on account same gas, endowed with the same of its unwillingness to enter into any physical and chemical properties. And chemical combination they proposed yet this was not the case. Nitrogen for it the name of argou. The discovobtained from the atmosphere by any ery was announced at Oxford, at the one of the usual methods was regularly last meeting of the British Associaby about one-half per cent. heavier than tion. nitrogen obtained in the chemical way from some compound. In each of the two sets of determinations the measurements beautifully agreed together; but the two sets totally disagreed, although all possible precautions had evidently been taken to prevent contamination by other gases, and a strong control was exercised to detect contamination if it had taken place. The disaccord had to be explained.1

This announcement, as already mentioned, was met with a great deal of distrust, which only grew stronger as time went on, and nothing was heard during the next five months in support of so important a statement. It was only after all the details of the researches were made public at the end of January last that all doubts as to the real existence of a new constituent of the atmosphere were removed, and the whole inquiry was recognized by competent judges as an exemplary chemical research."

The nearest explanation was, of course, to find fault with the chemically prepared nitrogen; notwithstanding all precautions it might still contain some The first step to be made in an inlighter gas hydrogen, for instance; quiry of this sort is evidently to obtain but test experiments were installed and the new body in sufficiently large quancompelled the rejection of this expla- tities for chemical analyses. This nation, so that there remained but one proved, however, to be a hard task. If other alternative-namely, that the argon easily combined with other atmospheric nitrogen, supposed to be bodies, any amount of it could be obthe purest of the two, was not pure at tained, because the nitrogen of air, of all; that it contained some heavier gas which there is an unlimited supply, which enters into the composition of contains as much as one per cent. of the atmosphere to no small amount, argon. But the new gas refuses to enbut in some way or another had hith- ter into chemical combinations, and it erto escaped notice. Lord Rayleigh is necessary to absorb all the oxygen, naturally hesitated to draw a conclu- nitrogen, carbonic acid, and so on, from sion so much opposed to all current a given considerable volume of air, and opinion, and in his perplexity he applied through the medium of Nature to chemists, asking them to aid him with their suggestions. The suggestions came, and in a great number; but none of them explained the difficulty. Some time later, Professor Ramsay asked and obtained permission to investigate the matter, and the two explorers, the

1 The average weight of one litre of nitrogen was 1-2572 grammes when it was derived from the atmosphere, and 1.2505 grammes for chemically obtained nitrogen.

2 September 29, 1892, vol. xlvi., p. 512. See also his two subsequent communications to the Royal Society.

to obtain argon as a residue. Yet nitrogen in its turn is also a very inert body, which it is by no means easy to force into a chemical combination; so that, after oxygen and the rest have been eliminated, there is still the difficulty of removing nitrogen from the mixture. It must, for instance, be passed for hours again and again over 3 Proceedings of the Royal Society, January 31, 1895; Nature, February 7, 1895, vol. li., pp. 347– 356.

Mendeléeff, Proceedings of the Russian Chemical and Physical Society, March 2 (14), 1895; and in Nature, vol. li., p. 543; Berthelot in Comptes Rendus, February 4, 1895, tome cxx., p. 235 sq.