March 26, 1903] 



NA TURE 



497 



proportionately with the amount of sunlight cut off, the 

 earth and moon should produce effects inversely proportional 

 to the square of their diameters, i.e. 135 : 1, and in 

 analysing the collected data Dr. Bauer finds that the ratio 

 of the diurnal variation to the eclipse variation is of this 

 order, thereby supporting the theory set forth in the preface. 



THE SOLIDIFICATION OF FLUORINE AND 



THE COMBINATION OF SOLID FLUORINE 



WITH LIQUID HYDROGENA 



T N preceding researches we have shown that fluorine is 

 liquefied at — i87°C, and that, at this low temperature, 

 it acts neither upon crystallised silicon, amorphous carbon, 

 ■boron nor mercury ; that, in short, its chemical activity is 

 diminished, but that it still combines with production of 

 flame with hydrogen and solid turpentine. 



These researches have been continued since one of us has 

 been able to obtain hydrogen in the form of a stable liquid 

 boiling at — 252°'5 C, or at 2o°'5 absolute. Since the first 

 experiments published on this subject it has been found that 

 fluorine which is perfectly free from hydrofluoric acid does 

 not attack glass at the ordinary temperature ; hence it is now 

 possible to enclose a definite volume of fluorine in a thin- 

 walled glass vessel, and to submit it to the powerful cooling 

 action furnished by the ebullition of liquid hydrogen. 



A sealed glass tube filled with fluorine and placed in liquid 

 oxvgen, boiling quietly under the atmospheric pressure, 

 showed no trace of condensation. The same tube was lowered 

 slowly into a double-walled vessel containing liquid hydrogen, 

 so as to obtain a progressive cooling. A yellow liquid first 

 appeared, which, after plunging wholly into the liquid 

 Tivdrogen, froze to a yellow solid. On leaving the tube for 

 some time in the liquid hydrogen, so that the temperature 

 of the fluorine was cooled down to 20°'5 absolute, the solid 

 fluorine, originally yellow, became white, resembling in this 

 respect chlorine, bromine and sulphur. Experiments with 

 liquid nitrogen showed that the melting point of fluorine is 

 below — 2io°C, and a comparison with the melting point of 

 oxygen, 38° absolute, showed that 40 absolute, or — 223 C, 

 is the most probable value for the melting point of fluorine. 

 The ratio of the melting point to the boiling point is a little 

 smaller than the ratios given by chlorine and bromine. 



Experiments were also directed to another point, the ques- 

 tion of the affinity of bodies for each other at low tempera- 

 tures, and in view of the fact that fluorine possesses more 

 powerful affinities than any other elements, it was interesting 

 to determine whether any action was possible between liquid 

 hydrogen and solid fluorine, both maintained at a tempera- 

 ture of — 252°'5. In order to realise this experiment, a thin 

 glass tube was taken containing about 50 c.c. of gaseous 

 fluorine, which had been completely freed from hydrofluoric 

 acid, the gas completely solidified in one of the points of the 

 tube, and this then immersed in a hundred cubic centimetres 

 of liquid hydrogen. When the temperature of the whole was 

 lowered to that of the liquid hydrogen, the point containing 

 the fluorine was broken off without removing the tube, so as 

 to allow of contact between the hydrogen and the fluorine. 

 A violent explosion was the result, sufficient heat being set 

 free to raise the material to incandescence and to set fire to 

 the hydrogen. The explosion was sufficiently powerful to 

 reduce the fluorine tube and the double-walled hydrogen 

 vessel to powder. 



HeHum is now the only gas which has not been obtained 

 in the solid state. 



THE ACCUMULATION OF METEOROLOGICAL 

 OBSERVATIONS. 



"OROF. HANN contributes to the Meteorologische Zeit- 

 ^ schrift for January a translation into German t>f that 

 portion of Prof. Schuster's address before the British Associ- 

 ation at Belfast (Nature, vol. lxvi. pp. 614-618) which deals 



1 A paper, by Profs H. Moissnn and J. Dewar, read before the Paris 

 Academy of Sciences. March 16. 



with meteorological observations, and adds some comments 

 from which the following extracts are translated. 



NO. 1743, VOL. 67] 



Prof. Schuster's point of view is that of the theoretical 

 physicist, and it is consequently different from that of the 

 meteorologist, who cannot leave the demands of practical 

 life out of account. 



The professor's remarks as to the desirability of short 

 and systematic series of observations for the study of de- 

 finite problems, that is to say, the introduction of a kind 

 of experimental method into meteorology, will certainly 

 meet with universal approval, but this has already been 

 done in several cases (study of thunderstorms, effect of 

 forests on climate, &c). Simultaneously with such special 

 observations the regular " routine observations " need in 

 no wise be neglected ; they appear to us to be indispensable. 



Complaints as to the superabundance of meteorological 

 observations are not new ; it may be a quarter of a century 

 since we read in an English periodical : " The need in 

 meteorological science now is not observations, but brains to 

 work out the results." It cannot be denied that there is 

 some justification for this point of view, but it must be 

 borne in mind that by reducing the number of meteorological 

 records the number of " brains " who would discuss already 

 available observations would hardly be increased. 



A small amount of consideration will further show that 

 the question of a temporary suspension of meteorological 

 observations cannot be regarded as a practical one. The 

 central institutions could take no such step, for they are 

 not intended solely, or even primarily, to serve the ends 

 of pure science, but chiefly to meet the demands of practical 

 life, which would not brook the interruption of observ- 

 ations for a lustrum. The answer given by Sir George 

 Airy before a Treasury Committee appointed to inquire into 

 the expenditure of the grant in aid of meteorology is charac- 

 teristic in this connection. Asked whether there were reasons 

 for continuing the publication of the detailed daily reports 

 from the seven (first-class) observatories, Airy replied : " It is 

 desirable they should be preserved, I think; and there is one 

 point which is worth considering, and that is that the public 

 feeling in favour of meteorological publications is very 

 strong. ... I get a great number of letters and applica- 

 tions of all'kinds from persons that I know nothing about. 

 Few requests are made for astronomical information. A 

 greater number are made for magnetic information, but 

 that is to a great extent for practical purposes; but I think 

 that by" far the greater number are for meteorological in- 

 formation. . . . Popular feeling is an element not to be 

 put out of question in matters of this kind." This from 

 the same Airy who later on expressed the wish " that an 

 absolute stop should be made from time to time in order 

 to give what I venture to call breathing time." But prac- 

 tical and scientific demands alike pass over such desires. 



Had Prof, Schuster ever been at the head of a meteor- 

 ological office, he would know how constantly public authori- 

 ties, to say nothing of private individuals, demand authentic 

 meteorological data ; he would then be able to estimate what 

 public opinion would say if the director answered : " I have 

 discontinued meteorological observations for five years, to 

 obtain time and opportunity for discussing existing records." 



Even if official observations were suspended, private 

 observations would be continued, and a state of affairs 

 would again be brought about similar to that which obtained 

 before the introduction of an organised system of observ- 

 ation. Unchecked observations would be made with un- 

 tested and badly exposed instruments, and a real waste of 

 time would result, nay more, in many cases positive harm 

 might be done by the circulation of inaccurate data. A 

 natural interest, which has undoubtedly done good service 

 in the past, would also be checked. 



As regards the publication of results, it is only by means of 

 such publications that it is possible on the one hand to 

 exercise satisfactory supervision over the observations, 

 and on the other to give all who desire it the oppor- 

 tunity of making use of existing records. To bury the 

 results where they would be accessible only to the staff of 

 an office would be a waste that would indeed justify com- 

 plaints. 



Least of all can we understand how Prof. Schuster could 

 mistake the value of continuous homogeneous records or 



