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A Neglected Correction in Osmotics.

IN the dynamic method of determining relative vapour pressures, air, initially dry, is passed first over the solution and then over the pure solvent. When it leaves the solution it has taken up a quantity of solvent vapour 1,; on leaving the solvent it contains a further quantity, 1-1. While working on aqueous solutions at o° C., Mr. Hartley and I had realised that the air when over the solution expands by an amount represented by the vapour pressure of the solution, similarly a further expansion takes places over the solvent, but as this further expansion is only that due to the difference of vapour pressures of the two liquids-say 1/10th of 4 mm. Hg-we had assumed that this small quantity was negligible in comparison with the total pressure.

Dr. C. V. Burton, of my laboratory, has pointed out to me that this assumption is not justified when osmotic pressures are to be calculated from the observed results. His discussion of the necessary correction is as follows. Let B be the barometric pressure and V the volume of air (measured when dry) passed through the system. The air in contact with the solution has a partial pressure of B-, and the volume now occupied by it is increased to VB/(B—ñ„). Similarly, on leaving the solvent the volume has become VB/(B-). If p, and p are the densities of the vapour in equilibrium with the solution and solvent respectively, the masses 1, and 1 are P, VB/(B- and PVB/(B–π。).

Assuming that Boyle's law holds good for the vapour up to , with sufficient accuracy for the purpose of the correction, we can replace π by P/P We have then what amounts to a simple equation in po/P1; its


solution is pd/p1 = 1/4-(2; − 1 ).


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IN his admirable article in NATURE of February 18 under the above heading, Prof. Jocelyn Thorpe dealt in a very concise manner with the grave difficulty which must seriously hamper all the present efforts to establish chemical industries in this country in successful competition with Germany. Particularly his remarks that the scientific worker has found by sad experience that little financial profit accrues to him even though he goes to the trouble of obtaining patent protection for his discovery, are of interest.

In this country, when an inventor applies for patent protection, a novelty search is made by the Patent Office in respect of his invention, solely among British patent specifications published before the date of his application during a period of fifty years. In contradistinction thereto the examiners at the German Patent Office investigate all printed publications of the last one hundred years prior to the date of such application. These publications include not only German patent specifications, but patent specifications and text-books of every country in the world. The applicant's attention is directed to any prior publication or text-book dealing not only with the particular subject but containing even remote suggestions that may lead up to that particular discovery.

Now, while this somewhat gigantic problem of the German Patent Office cannot in all cases be efficient and free from fallacy, it is, nevertheless, quite clear that the result of such a search must in a large number of cases be of greater value than that of the limited search carried out by the British Patent Office. In this manner, therefore, the inventor, if his discovery is found novel and patentable in Germany, has not only the satisfaction of having his invention tested quasi from an international point of view, but what is more valuable to him, he has his attention directed to knowledge existing and discoveries made also outside his own country.

Due to this wide scope of the official search, apart from other stringent considerations connected therewith, fewer patents are, of course, granted proportionately in Germany than are granted in this country, and it would, indeed, be interesting to examine how many of the discoveries for which patents have been granted in this country, for instance, in respect of aniline dyes, have, in fact, been protected also in Germany. A number of these British patents on which royalties are probably being paid, or will be paid in the near future, would, perhaps, not stand a test before our courts, since prior text-books or a prior foreign specification may be relied upon in an action before a British Court, while the Comptroller-General of Patents has no right to consider such publications before granting a patent.

I have heard it argued that our limited search was good enough, because if there was anything worth patenting anywhere, it would certainly be patented in this country. I venture to suggest that this is as much an antiquated idea as prevailed, until this war opened our eyes to the present industrial situation, with regard to the industrial supremacy of these islands shortly after the time when Section 27 of the Patents and Designs Act of 1907 was called into being. In this connection it is interesting to recall a famous phrase uttered by Mr. Justice Parker (now Lord Parker) in his decision in the matter of the revocation of Hatschek's patents, Nos. 6455 of 1900 and 22,139 of 1900, viz. "However great may be one's belief in the industrial supremacy of the inhabitants of these islands, it would at least be somewhat arrogant to assert that wherever the manufacture of a patented article in the United Kingdom is less than one-half of the total manufacture of the whole world, there arises a presumption that British trade has not had fair play."

The decision involved a matter of great importance to patentees, manufacturers, and British traders, and it was justly stated that the whole industrial world was anxiously awaiting the dictum on that famous section of the Act.

The greatest anxiety, of course, prevailed in Germany, and this was natural in view of the many British patents taken out by German chemists and chemical concerns for the purpose of biocking the industry in this country rather than of developing it.

Now, why has that section failed to do that which it was actually framed for? To my mind there are several important reasons. The average manufacturer does not possess the knowledge that chemical manufacture cannot in these times be carried on without his close co-operation with highly trained chemists, and, true to old-established tradition, he is prejudiced to any such co-operation. Further, he is constantly faced by the danger of infringing existing British patents, and even though he may be aware that the patents blocking his way are mere 'paper" patents and that he has every reasonable hope to succeed in an action for infringement or revocation thereof, the exceedingly high cost at present connected with any action must have an important effect on his hesitative

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attitude, and largely accounts also for the perpetual success of those whose business it is to defy the section and to maintain their "unworked" patents to the detriment of the British industry. JUSTIN E. POLLAK.

London, March 4.

Measurements of Medieval English Femora. PROF. KARL PEARSON'S criticisms are always welcome and stimulating to those strong enough to bear them though, since they are usually of the destructive variety, the fear of them undoubtedly prevents a good deal of work which would add to our knowledge being published. Let me deal, for instance, with the following criticism. "Looking at Dr. Parsons's results I can but conclude that his sexing is based on a fallacy, and the dip he has created in the Rothwell femora between those with 45 and 47 mm. heads—the range of Dwight's doubtful sex-is due to conscious or unconscious selection of his material; out of the great masses of bones available at Rothwell (which should have occupied in measurement of many characters and in their adequate reduction the whole time of a man for four or five years)."

By "conscious selection of material" I can scarcely think that deliberate fraud is suggested-I do not indeed know what it really means; while unconscious selection I suppose is covered by inaccurate measurements or by the absence of bones of a certain size which ought, mathematically, to be there.

At any rate, the impression conveyed by the stricture is that, from an enormous available mass of material, I have deliberately or unfortunately picked out a small selection which would bear out some object which I wished to prove

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It is almost inconceivable that Prof. Karl Pearson would have mentioned the great masses of bones available" unless he really knew what he was talking about, so that we may safely assume that he has been to Rothwell and satisfied himself on this point.

I can only say that I have spent a great deal of time at Rothwell, and that I found considerable difficulty in picking out 300 measurable femurs, and this was particularly the case with the slighter bones which, owing to the damp, snapped like carrots when


I can assure Prof. Pearson that every measurable bone which could be extricated was welcome, and none were rejected because their sizes did not suit.

As to four years of a man's whole time being needed for the research, I can only infer that Prof. Pearson thinks that there is unlimited measurable material at Rothwell, and that, if I could not give the time he thinks necessary, I had better have left it to some other man who could. These really are the words of the "mere mathematician" ignoring all practical details. Did not Prof. Pearson observe when he went to Rothwell that the bones were rotting with damp exactly the opposite condition, by the bye, to his Naquada bones-and that the farther he worked into the stack, for he must have done this or how would he otherwise have known about the " great masses of bones available"? the more sodden and useless the material became? As no one else showed the least sign of spending even four weeks in working at the Rothwell bones, I did what I could while I could, for if I had left it for another ten years the available material would have been much less. Incidentally, I advised the restacking of the heaps, so that air now gets among the bones, and they will not disintegrate so rapidly. There is another practical point, too, about which Prof. Pearson is silent; it is the fact that the ordinary anatomist has difficulty in getting unlimited measurements recorded, and my contribution of six

teen sets of measurements on nearly 300 bones was all I could fairly expect our journal to print for me at one time.

In other points I think that Prof. Pearson and I are in practical agreement. We agree that neither of us can sex femurs with accuracy (I find that in eighty-two attempts I made seven mistakes), but that, when we have sexed them to our individual taste, the average difference in results is a fraction of a millimetre. We both agree that the head measurement alone is often liable to mislead, and that a series of secondary sexual tests of graded value are needed. These I have attempted to provide in a paper which will appear shortly, and of which I will not fail to send Prof. Pearson a copy.

Above all, I am glad to see that he tacitly agrees with me about the Rothwell bones being medieval, probably of the fourteenth and adjacent centuries. F. G. PARSONS.

St. Thomas's Hospital, S.E.

The Green Flash.

PROF. PORTER's interesting letter (NATURE, February 18, p. 672) on this subject must be my excuse for sending a summary of my own experience during the last eighteen years in which I have observed the flash more than a hundred times, and in no single case did I find anything not explainable by atmospheric dispersion, nor anything that could be put down as a subjective or complementary afterimage.

I may add that I have observed with the naked eye, with an opera-glass (power 3), with binoculars (power 9), and with a telescope (power 100).

Whenever on a clear day a low sun is observed through a telescope, the upper limb appears bordered with a marine, i.e., blue-green, fringe, the lower with an orange-red fringe, the side-limbs are unaltered. (The telescope should have a solar diagonal and other means of reducing the brightness of the sun.).

The marine upper fringe develops ultimately into the green flash, the blue element weakening as the sun descends. I have watched this change with the telescope, and it is perfectly continuous.

Again, if the sun descends behind a low cloud, parallel to the horizon, but with a clear space between, the base of the sun, just as it becomes visible, shows the red flash. I have seen this only thrice, as the necessary conditions are obviously seldom satisfied. The red flash seems inexplicable save by dispersion.

Under favourable conditions at sunset, as the upper segment of a yellow sun gradually diminishes, the right and left corners of the segment become green; this colour gradually spreads inwards, becoming marine, until finally the last tip of the sun may appear almost greenish-blue, and just as the sun has sunk, a very faint wisp of blue light is glimpsed directly above the point of disappearance. One friend even records a violet wisp.

But when the sun is orange the blue is replaced by green, and when the sun is really red no green flash at all is seen, the atmosphere cutting off the green as well as the blue rays. To see these changes it is desirable to use a power of 8 or 9.

Prof. Barnard, writing to me some years ago, said he preferred the title, "blue flash," as in sunsets seen over the Pacific from the Lick Observatory the final flash was usually blue. Doubtless this is due to clear atmosphere.

It is well known that at sunrise, when no exciting colour can be present, the flash has been seen, sometimes green, sometimes blue.

In the 1906 volume of Symons's Meteorological

Magazine appears correspondence on this subject by Dr. Rambaut, myself, and others, and the editor, Dr. Mill, in summing up the matter, decided strongly in favour of the dispersion theory. Capt. Carpenter, R.N., whose numerous observations appear in the British Astron. Assoc. Journal, holds the same view.

It is quite true that, if I look steadily at a bright red sun, and then close my eyes, I see a green afterimage, but this is just what the observer of the green flash should not do. He should avoid looking at the sun when it is bright, and should wait until it is so low that the eye can easily bear the lightshould wait, in fact, until only a very small segment As before stated, with a really red sun is visible. the flash fails to appear, so far as my experience goes. If proper precautions are taken I do not think any appreciable after-image will be present.

I may point out that the nature of the horizon, provided it is clean-cut and low down, makes but little difference. It may be of cloud, land, or water, and, of course, the last is the best. My experience relates to all three.

But few persons appear to have used a telescope for observing the flash. If those who have not done so would observe a low sun with a power of, say, 100, I think that they would be convinced that the true cause was atmospheric dispersion.

The real mystery about the flash is that it so often fails to appear, when apparently all conditions seem favourable. I have not yet found any explanation of this, but I am inclined to the opinion that at a clear sunset the flash could always be seen if a telescope were available, though it might be too feeble for the naked eye, for a telescope invariably reveals the upper green fringe when the sun is low. The telescope, of course, was achromatic, and showed no colour with a high sun. To the Journal of the B.A.A., to that of the Leeds Astron. Society, and to the English Mechanic I have contributed very numerous notes on this subject, but references to them would occupy too much of your valuable space. C. T. WHITMELL. Invermay, Hyde Park, Leeds, February 22.

The Prices of Chemicals.

I HAVE had the same experience as "S. P." Since my letter of February 18 I have been able to purchase dulcite at 60s. an ounce from a firm of dealers in chemicals other than the one to which I. referred. I cannot admit, therefore, that my complaint was unjustifiable. J. J.

University of Liverpool, March 2.


THIS book is the diary of a very interesting journey accomplished by the author in the course of the autumn of 1913. In fact, it describes four different journeys: one from Tromsö, via the Kara Sea, to the mouth of the Yenisei; then up the Yenisei to Krasnoyarsk; next by rail across Transbaikalia and Manchuria to Vladivostok on the Pacific; and from this port to Petrográd, by the Usuri and the new Amur railway and the main Trans-Siberian line. A remarkable feature of this journey, during which more than 16,000 miles were covered, is that it was accomplished in less than three months, from August 5, when the party started from Tromsö,

"Through Siberia, the Land of the Future." By Dr. F. Nansen. Translated by A. G. Chater. Pp. xvi+478. (London: W. Heinemann 1914.) Price 155, net.


October Petrográd.

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We cannot expect to find detailed descriptions of the different portions of the immense continent thus rapidly crossed; but the book throughout has the greatest interest, owing to the human element it contains, and the unexpected glimpses it gives of the Canada of the East, with its wonderful development during the last fifteen years. In addition, it is illustrated by more than 160 beautiful photographs, taken by the author himself, most of which worth pages of descriptions. The ethnographical remarks about the northern natives, whose encampments, or boats, Dr. Nansen always found time to visit, especially about the remaining members of that curious, once numerous, nation, the Yenisei Ostyáks, will be read with a special interest; while the photographs, as may be seen from the two accompanying specimens, give a clear idea of the ethnographical types of the different native tribes.

The really difficult part of the journey, from Tromsö to the mouth of the Yenisei, was made on the steamer Correct, with the experienced pilot Capt. Johannsen, without meeting with serious difficulties. There was a good deal of ice in the Kara Strait, and especially further east, so that. the Correct had to enter the Kara Bay in order to follow the narrow, more or less ice-free channel close to the coast of the Yalmal peninsula. There was only one dangerous accident, when the steamer stuck on a mud bank close by the Devil's Island; but otherwise the journey was quite successful, and it took only eighteen days from the day the steamer entered the Kara Strait to the day it reached the port at Nosónovskiye Islands, in the Yenisei, under the 71st degree of latitude.

Once more the practicability of the northern route to Siberia was thus demonstrated. But it must be said that the conditions of ice along the northern coast of Siberia show great variations in different years, and in 1913 they certainly were by far not so favourable as they were in the years 1870-1871 and 1875–1878. A very valuable appendix, where the average summer temperatures on the shores of the Kara Sea and the conditions of ice in that sea are given for the last forty-one years, shows that while this passage was remarkably free from ice in the years named, as well as in 1890, 1897, 1900, 1901, and 1904, the conditions were not favourable for navigation in 1883, 1884, 1888, 1911, and 1913, unfavourable in 1895 and 1902, and most unfavourable in 1903 and 1912.

Still, Dr. Nansen is certain that the northern route may become a regular line of traffic if certain measures are taken. During his journey up the Yenisei, and later on along the TransSiberian railway, he had full opportunities to discuss such measures with M. Vestrótin, a Russian merchant and member of the Duma who has great knowledge of the Siberian north, and also made the journey on the Correct, and

M. Wourtzel, the head of the traffic on the
Siberian railway.

"We had," Dr. Nansen writes, "great deliberations in the saloon [of the train] as to how the trade route between Norway and the Yenisei could be best secured, and what were the first steps to be taken to this end. We discussed the best arrangement of wireless stations, the dispatch of motor sloops to investigate the extent of the ice in the Kara Sea, how aeroplanes might be used for constantly reconnoitring the ice-conditions of the sea, in connection with the wireless stations, and so on. The construction of an efficient harbour for discharging and loading in the northern part of the Yenisei and the transport up and down the river were discussed with Vostrótin, who has these questions at his fingers' ends. By

native huts to Krasnoyársk, with its gilded cathedral, public park, museum, schools, and electric light in the streets-all the town profusely illuminated to welcome the Norwegian guest-all this, most sympathetically told by Nansen, is fascinating reading.

At Krasnoyarsk Dr. Nansen took the luxurious eastern train which brought him in four days, from September 29 to October 4, to Vladivostok on the Pacific. Notwithstanding the rapidity of this journey, we still find in Dr. Nansen's book very interesting remarks about the the condition of Siberia, the causes of its slow colonisation, and the rapid strides it has made since the Manchurian



Group of Yenisei-Ostyáks. From "Through Siberia." By Dr. F. Nansen. (London: W. Heinemann.)
(The figures in the background, left and right, are Russians.)

degrees a whole programme was drawn up under the
shrewd guidance of Wourtzel."

The journey up the Yenisei to the town Yeniseisk, made in a little motor steamer, Omul, offered Dr. Nansen the opportunity of making many fine remarks about a variety of subjectsBaer's law of excavation of the right banks of rivers; the first appearance of larches; the exiles scattered even within the Arctic circle and living in tiny primitive huts, the first appearance of agriculture and cattle-breeding, and so on. rapid change on this journey, from the endless. treeless tundra to the thick forests region, the gradual growth of the clusters of "snug, low timber buildings," into villages, and further south into towns, and the transition from the isolated


Winter was rapidly setting in, and next day Dr. Nansen had already begun his return journey -this time on the railway which runs down the valley of the Usuri to the new town of Khabaróvsk, which I knew fifty years ago as a village of a score of houses. The great railway which is now built by the Russian Government along the left bank of the Amur had not yet reached this new capital of the Lower Amur region. An immense bridge, 7827 ft. long, on nineteen piles, is being built below Khabarovsk across the Amur; and this bridge, as well as the lowlands on the left bank, representing an immense swamp for some 200 or 300 miles, often inundated during the monsoon rains, offer great difficulties to the engineers. The journey across this marshy

region, as well as the crossing of the Little Khingán, were made by Dr. Nansen, partly in horse carriages, partly in trolleys run along temporary rails, and partly in a motor-car, until he reached, on the Zéya plain, about 420 miles from Khabaróvsk, a station where he could take the direct train to Petrográd. This station, from which Dr. Nansen could now travel by rail all the way to Petrográd, with but one or two interruptions at unfinished bridges, received from the local engineers the name of "Nansen's."

On October 18 Nansen was at Chitá, where he joined the Eastern Express. He passed Irkútsk at night, without stopping; six days later he was


DR. BRUN, of Zürich, has done a fine piece of work in devising an elaborate and ingenious series of experiments which enable us to come to a decision among the rival theories of way-finding among ants. Let us first illustrate the facts. If we pick up one of the higher ants from an antroad, turn it about in a box, and then empty it out again near the place of its capture, it makes no mistake in hurrying homewards. When an ant goes off alone on an exploring adventure, it often keeps persistently in one general direction, in spite of many divagations to one side or the other, and


Men and women of the Yuraks and Yenisei Samoyedes. From "Through Siberia." By Dr. F. Nansen. (London: W. Heinemann.)

in the Urals, and on October 27 he reached Petrográd; and yet, notwithstanding the rapidity of the journey, his observations and remarks about Siberia, "the land of the future,' "Russia in the East," and "The Yellow Question," and so on, are both valuable and interesting.

The book is richly produced, with numerous excellent reproductions of Dr. Nansen's photographs, and with three maps-one of the Kara Sea and adjoining lands, and two of Siberia. The transcription of Russian names, both in the text and on the maps, is quite correct, with the exception of a very few words, in which the German spelling has been followed (Tas, Seya, Syriansky, instead of Taz, Zeya, Zyriansky). P. KROPOTKIN.

when it turns its face homewards, it does not usually retrace its steps, but pursues a parallel course until it comes near the nest. If a higher ant, such as Formica rufa, be gently but firmly induced to travel on a path chosen for it and not by it, it makes straight for home when freed from coercion. It may run along a line which is the hypotenuse of the triangle the other two sides of which it was compelled to follow, or it may complete a polygonal figure and reach the nest. members of such species as Formica rufa and F. sanguinea be lifted up and carried some distance and put down in hunting ground which they have 1 "Die Raumorientierung der Ameisen und das Orientierungsprob'em im allgemeinen. Eine kritisch-experimentelle Studie; zugleich ein Beitrag zur Theorie der Mneme." By Dr. Rudolf Brun. Pp. viii+234 +51 s. (Jena: Gustav F scher, 1914.) Price 6 marks.

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