3o8 



NATURE 



[June 14, 1917 



opinion on this matter, and this may have led 

 certain of the contributors to hesitate in giving- 

 it. Others, however, have been able to read 

 more clearly the signs and portents of the times, 

 and, on the vi^hole, their testimony is reassuring 

 and full of hope. There can be no doubt what- 

 ever that the general body of chemical manufac- 

 turers in this country, as well as of the manu- 

 facturers def)endent on chemical industry, have 

 had a rude awakening. The war has completely 

 upset commercial conditions, and many genera- 

 tions must come and go and a long period of 

 peace ensue before pre-war relations are resumed. 

 Public sentiment will force this country to depend 

 more and more upon its own efforts, and to 

 develop to a far greater extent its own internal 

 resources. There is a general recognition that 

 at the base of this problem is our educational 

 system, and we see the evidence of this fact in 

 the appointment of a professed educationist as 

 director of a new policy. It is being realised that 

 science and the methods of science must enter 

 more largely into the _ curriculum of our 

 secondary schools, and that colleges of science 

 must be multiplied and strengthened. It is now 

 everywhere perceived that the future of all 

 industries depends upon science and upon the 

 application of scientific principles. The bread 

 that has been cast upon the waters is now being 

 found after many days. 



Many proofs of this fact are to be met with 

 in the volume before us, accompanied, we regret 

 to add, with certain disquieting features. There 

 are those who aim at ends which are not those of 

 their country, and too many new activities are 

 secret. Perhaps in the circumstances this is 

 unavoidable; but, as the example of our enemies 

 has shown us, those industries flourish best and 

 develop most rapidly where their leaders co- 

 operate for their Common good, even though they 

 may themselves combine contra mundurn. 



Progress in applied chemistry may be measured 

 by different standards. From an economic point 

 of view it may be estimated by the wealth it brings 

 to a community. This aspect of the matter finds 

 practically no mention in the compilation before 

 us. It is probably difficult to get together the 

 requisite information, but if the Society oi 

 Chemical Industry could be induced to add a 

 statistical department to its staff and pub- 

 lish the results of its labours each year as a 

 supplement to these annual reports, we should 

 obtain a real and valuable measure of the pro- 

 gress of the chemical arts in this country. As it 

 is, the present work is too obviously based upon 

 the pattern of the annual reports published by the 

 Chemical Society, and is too exclusively a 

 catalogue raisonnS of the yearly output of the 

 literature of applied chemistry. We would by no 

 means undervalue the worth of such a compila- 

 tion, but we venture to believe a fuller measure of 

 its usefulness might be secured by a further 

 extension of its scope. 



These observations are offered in no spirit of 

 carping criticism. We welcome with sincere 

 pleasure the advent of an enterprise which is 



NO. 2485, VOL. 99] 



bound to have a far-reaching influence on the 

 development of chemical industry in all English- 

 speaking countries. Its inception at the present 

 juncture is most timely, and we heartily wish it 

 success. Thanks to the energy, skill, and 

 perspicacity with ■ which it is conducted, the 

 journal of the society has become its most valuable 

 asset. We are confident that these annual 

 reports are destined to be a no less valuable 

 feature of its work, provided that those who con- 

 trol its affairs are determined to rise to the full 

 extent of their opportunity. 



THE RADIATION OF THE STARS. 



SINCE the publication of Homer Lane's paper 

 " On the Theoretical Temperature of the 

 Sun " in 1870, many writers have discussed the 

 internal state of a star, considered as a globe of 

 gas in equilibrium under its own gravitation. 

 Recent observational work gives encouragement 

 to these investigations, for it is now known that 

 numerous stars are in a truly gaseous condition 

 with mean densities similar to that of our atmo- 

 sphere. To such stars the results for a perfect gas 

 may fairly be applied, whereas stars, such as the 

 sun, with densities greater than water must 

 necessarily deviate widely from the theoretical 

 conditions. The stars which are in a perfectly 

 gaseous state correspond to the " giants " on 

 H. N. Russell's theory,^ or to the stars of rising 

 temperature on Lockyer's principle of classifica- 

 tion; the denser "dwarfs" are outside the scope 

 of this discussion. The two series coalesce for 

 spectral type B, which marks the highest tempera- 

 ture attained. 



The internal temperatures which have been 

 calculated are so far beyond practical experience 

 that we may well hesitate to apply the familiar 

 laws of physics to such conditions. But in so far 

 as the investigation can be based on the second 

 law of thermodynamics, the conservation of 

 momentum, or laws which are directly deduced 

 from these, there can be little doubt of the 

 validity of the treatment. We cannot altogether 

 avoid assumptions of a speculative or approxi- 

 mate character, and no doubt some of the results 

 described in this article are open to serious 

 criticism on that account ; but to a considerable 

 extent the discussion can be made to rest on laws 

 which are held to be of universal application. 

 Moreover, natural phenomena usually become 

 simpler at high temperatures ; gases become more 

 " perfect " ; the absorption of X-rays follows 

 simpler laws than the absorption of Hght; the 

 heat-energy comes to be located in greater pro- 

 portion in the ether, so that the precise nature 

 of the material atoms is less important. 



Most investigators have assumed that the stars 

 are in convective equilibrium. ^ In that case, when 



1 Nature, vol. xciii., pp. 227, 252, and 281. 



'■2 There are strong reasons for believing that the interior of a star njust be 

 in radiative equilibrium, not convective equilibrium. The internal dis- 

 tribution of temperature and density is, however, of the same character in 

 either case : if the coefficient of absorption is independent of the tempera- 

 ture, then the distribution corresponding to radiative equilibrium is the 

 same as that of material for which y=i in convective equilibrium. S«e 

 Monthly Notices, K.A.S., vol. Ixxvii., p. 16. 



