108 



KNOWLEDGE 



[June 1, 1892. 



of oxygen and conditions favourable to evaporation. The 

 correctness of this conchision is well shown by the 

 following facts. If Phosphorus be placed in hydrogen, 

 or in carbonic acid, no glow is 'seen, but traces of 

 Phosphorus vapours can readily be detected in the gas. 

 When one of these gases charged with the vapour- of 

 Phosphorus is brought into contact with oxygen gas, 

 a glow is at once observed. This glow is stronger in 

 the case of hydrogen than when carbonic acid is used, 

 which is in accordance with the fact that Phosphorus 

 evaporates more readily in an atmosphere of the lighter 

 gas. 



It appears that the glow of Phosphorus in oxygen is in 

 some way connected with the presence of ozone. 



It is a well-known fact that when a stick of Phosphorus 

 is placed in moist air, ozone is produced, and it has 

 further been observed that if a drop or two of ether, or 

 oil of turpentine, substances which destroy ozone, be 

 placed in the ozonized air of a vessel containing a piece of 

 the Phosphorus, the glow of the Phosphorus is at once 

 quenched. 



It appears probable that the glow is nothing else than 

 a very feeble flame, which may be seen when cuxum- 

 stances are favourable to the oxidation, or burning 

 of the Phosphorus. If the temperature be raised to a 

 moderate degree the combustion takes place with greatly 

 increased energy, and we get the ordinary flame of 

 burning Phosphorus. Recently Professor Thorpe, 

 and other workers at the Royal College of Science, have 

 investigated a similar case of phosphorescent appearance 

 due to oxidation. This occurs with the trioxiile oxide of 

 Phosphorus. 



When Phosphorus is burnt in a rapid current of air, 

 one of the principal products is the trioxide which is 

 capable of combinmg with a further dose of oxygen, forming 

 the better known and more stable substance, pentoxide of 

 Phosphorus. 



The phenomena accompanying this oxidation of the 

 lower oxide (the trioxide) have of late been carefully 

 studied. A phosphorescent appearance is observed when 

 oxidation occurs, and it has been found possible, by- 

 varying the conditions of temperature and of pressure, to 

 pass insensibly from the feeblest glow to the most brilliant 

 combustion. 



The trioxide is a more volatile body than Phosphorus 

 itself, and better adapted for experiments to show the 

 gradual passage from the " degraded combustion " of the 

 " glow " to the ordinary burning with visible flame. 



There are other well-known appearances besides those 

 presented by Phosphorus, which are due to degraded 

 combustion ; one example is furnished by the feeble 

 lambent flame seen inside the wire gauze of a Davy lamp 

 in "fiery" parts of a coalmine. The conducting power 

 of the wire gauze distributes the heat of the flame over a 

 large area, and prevents the inflammable gas outside the 

 lamp from becoming heated to the point at which 

 explosion occurs. 



The I'lnis fatuus is quoted as a still more striking 

 example of the degraded combustion of an inflammable 

 gas. Marsh gases, the slow combustion of which is 

 seen in the feeble flame of the will-o'-the wisp, consist 

 largely of methane, or fire damp, the explosive gas of 

 mines. 



Their slow oxidation (or degraded combustion) by the 

 air of the marshes produces at night time a faint glow of 

 uncertain or shifting position, to whose misleading light 

 have been attributed difiiculties of the road, as many as 

 have beset the search of scientific men after the true cause 

 of the glow of Phosphorus. 



THE NEW STAR IN AURIGA. 



By E. W. Maunder, K.R.A.S , 



Assistant superintend iti'i tlie Soliir and Spertruscopir Depart- 

 ments at the B(»j(il (Viaerrntorij, (rreennich. 



NEW" or "temporary" stars as they are some- 

 times called, oft'er many perplexing problems 

 for solution, and so far we have certainly not 

 arrived at any satisfactory conclusions respect- 

 ing them. First of all, we have the paradox 

 that they are evidently very minute bodies, for they cool 

 very quickly, quicker than a body even the size of one of 

 the minor planets could do, whilst they are also equally 

 clearly very large bodies, for in no single case has an 

 appreciable parallax been found for any one of them. 

 They are therefore situated at extremely remote distances 

 from us, and hence must be vast indeed for us to perceive 

 them at all when far off. 



Their spectra, too, rather confuse than help us. The 

 bright lines of hydrogen, and many of the chromospheric 

 lines familiar to us in the sun, point to a body similar to 

 our sun and the stars of the same class. But then, again, 

 we have other lines shown, which suggest analogies to the 

 Orion stars, supposed, with so much probability, to be 

 but recently formed from the dift'used nebulous matrix of 

 that constellation, and on the other hand we have ap- 

 pearances which suggest kinship with the stars of the 

 third type of spectrum, a type usually supposed to 

 represent a cooler, more condensed stage than that even 

 of the sun. 



The first difliculty has been attempted to be surmounted 

 by supposing that we have in a " new " star : (1) A 

 momentary flicker on the part of a nearly extinct sun. It 

 has been suggested that the still glowing nucleus is skinned 

 over by a thin non-luminous or feebly luminous crust, 

 that in some way or other this crust is temporarily broken 

 up, and for a time the hidden light and heat are able to 

 radiate themselves forth. (2i Or it is supposed that the 

 increase of brilliancy relates merely to the very surface of 

 the star, and does not denote any general increase in 

 temperature of the star itself. (3) Or that both state- 

 ments of the paradox are trae, and the star is both very 

 minute and very large ; or rather that it is composed of 

 bodies individually very minute, but m the aggregate 

 having an immense extension, and considerable mass ; in 

 other words, we have not to do with a star in any true 

 sense of the word, but with a stream or streams of 

 meteorites. 



How do the facts which we have learned concerning Dr. 

 Anderson's new star accord with these theories '? 



The first fact that we have is the increase of brightness 

 of the star, from fainter thau the eleventh magnitude on 

 November 2nd to brighter than the fifth magnitude on 

 December 20th. The photographs taken by Prof. Pickering 

 are our warrant for this statement. The star therefore 

 increased in brightness one thousand fold in less than 

 seven weeks, quite possibly in even a few days or hours. 



The next fact is that the principal source of this added 

 brightness lay in most intensely heated gases. The evi- 

 dence for this fact is the extreme brilliancy of the bright 

 lines which glowed in every part of the spectrum, from as 

 far down in the red as the eye could reach to the utmost 

 limit of recordable stellar radiations in the ultra-violet. 

 The existence of a bright line spectrum is in itself suf- 

 ficient evidence that it proceeds from highly heated gas ; 

 the existence of groups of such lines in the ultra-violet, 

 as far as lines have been discovered in the spectrum of the 

 mighty Sirius, is the most emphatic testimony we could 



