Hence we might be justified in supposing that D, and 4471 are produced by the same gas, while it was probable that 4302 owed its origin to a different one.

But further experiment has given me one case in which D, shows bright, while 4471 is entirely absent. I may now add that an equally important line to 4471, one at 4026-5, with the dispersion employed, appears in the spectrum of bröggerite, and both these lines are wide and fluffy, like the lines of hydrogen, and are apparently reversed.

The line 4026.5 has not been recorded by Young, though, as I have stated, the frequency of appearances of 4471 represents the maximum; still, while this is so, the intensity of both these lines in the spectra of the hottest stars is not surpassed even by those of hydrogen. Hence, opinion as to their representing the same gas must be suspended.

Further, I have photographed a line at 4388, apparently coincident with another important line in the same stars. Whether coming from one source or two, in these three lines seen along with D, in the gas obtained by me from bröggerite, we have, it would seem, run home the most important lines in the spectra of stars of Group III, in which stars alone we find D, reversed. Should these results be confirmed, the importance of the gas or gases they represent, at a certain stage of the evolution of suns and planets, will be gathered from the photograph of Bellatrix, accompanying the following Third Note.

Another case is afforded by a line a λ 667; this is associated with D3 in bröggerite and clèveite, but the yellow line has been seen in monazite without 667. It is almost certain, then, that these two lines represent two gases. Certainty cannot be arrived at till a larger quantity of gas has been obtained.

Again the red line at X 6575, close to C, referred to in my previous communication, is seen both in gummite and bröggerite, but in one case (gummite) it is seen without D, and in the other with it; in one case (bröggerite) without 1614, and in the other with it. The above conclusions hold here also.

This line 614, possibly coincident with a chromospheric line, has been recorded in gummite and bröggerite. It has been seen with D3 (in brüggerite) and without it (in gummite).

I have said enough to indicate that the preliminary reconnaissance suggests that the gas obtained from bröggerite, by my method, is one of complex origin.

I now proceed to show that the same conclusion holds good for the gases obtained by Professors Ramsay and Clève from clèveite.

For this purpose, as the final measures of the lines of the gas as obtained from clèveite by Professors Ramsay and Clève have not yet been published, I take those given by Crookes,* and Clève,† as observed by Thalén. These are as follows, omitting the yellow line :

:

The most definite and striking result so far obtained is that in the spectra of the minerals giving the yellow line I have so far examined, I have never once seen the lines recorded by Crookes and Thalén in the blue. This demonstrates that the gas obtained from certain specimens of clèveite by chemical methods is vastly different from that obtained by my method from certain specimens of bröggerite, and since, from the point of view of the blue lines, the spectrum of the gas obtained from clèveite is more complex than that of bröggerite, the itself cannot be more simple.

gas

Even the blue lines themselves, instead of appearing en bloc, vary enormously in the sun, the appearances being—

4922 (49213) = 30 times.

4713 (4712·5) = twice.

These are not the only facts which can be adduced to suggest that the gas from clèveite is as complex as that from bröggerite, but while, on the one hand, the simple nature of the gases obtained by Professors Ramsay and Clève, and by myself, must be given up, reasoning on spectroscopic lines, the observations I have already made on several minerals indicate that the gases composing the mixtures are by no means the only ones we may hope to obtain.

This part of the inquiry will be more specially considered in a subsequent communication.

I may remark in conclusion, that in this preliminary inquiry no

attempt has been made to separate the possibly new gases from the known ones which come over with them; hence, the lines are in some cases very dim, and the application of high dispersion is impossible. The wave-lengths therefore, especially in the visible spectrum, are approximations only; but the view that we are really dealing with gases operative in the solar atmosphere, like the helium which produces D3, is strengthened by the fact that of the sixty lines so far recorded as new in the various minerals examined, about half occur near the wave-lengths assigned to chromospheric lines in Young's table. I am aware that most of the chromospheric lines have been recently referred to as due to iron,* but I believe this result does not depend upon direct comparisons, and it is entirely opposed to the conclusions to be drawn from the work of the Italian observers, as well as from my own.

II. "On the new Gas obtained from Uraninite. Third Note." By J. NORMAN LOCKYER, C.B., F.R.S. Received May 9, 1895.

In my preliminary note communicated to the Royal Society on the 25th ult., I gave the wave-lengths of the lines which had been observed both at reduced and at atmospheric pressure in the gas (or gases) produced by the method to which I then referred of heating the uraninite mineral (bröggerite) in vacuo.

As a short title in future, I shall term this the distillation method. Since then the various photographs obtained have been reduced, and the wave-lengths of the lines in the structure spectrum of hydrogen observed beyond the region mapped by Hasselberg. I have further observed the spectra of other minerals besides uraninite for the purpose of determining whether any of them gave lines indicating the presence of the gas in uraninite or of other gases.

I now give a table of the lines so far measured in the spectra of eighteen minerals between AX 3889 and 4580 (Rowland), the region in which, with the plates employed, the photographic action is most intense.

On this table I may remark that of the lines given in my paper of April 25, the final discussion has shown that the following lines are hydrogen structure-lines in the region beyond that mapped by Hasselberg, A 4479, 4196, 4156, and 4152.5. The line 4368 is also omitted from this list as it has not been finally determined whether it coincides with a line of oxygen.

In the table, besides the wave-lengths on Ångström's and Rowland's scale, I give lines which have been observed in the sun's

* Scheiner's 'Astronomical Spectroscopy,' Frost's translation, p. 184.

Table.

Lines photographed in the Spectra of Gases obtained from various Minerals experimented upon up to May 6.

chromosphere and chronicled by Young; those photographed during the eclipse of 1893 with a 6-in. prismatic camera by Mr. Fowler, and those photographed with the same instrument at Kensington in some stars of Group III of my classification in the constellation of Orion.

This table carries the matter of the relation of the new gases to solar and stellar phenomena much further than I ventured to suggest in my second note. We appear to be in presence of the vera causa, not of two or three, but of many of the lines which so far have been classed as "unknown" by students both of solar and stellar chemistry, and, if this be confirmed, we are evidently in the presence of a new order of gases of the highest importance to celestial chemistry, though perhaps they may be of small practical value to chemists, because their compounds and associated elements are for the most part hidden deep in the earth's interior.

The facts that all the old terrestrial gases, with the exception of hydrogen, are spectroscopically invisible in the sun and stars-though they doubtless exist there-and that these new gases, scarcely yet

*The broad hydrogen line Hy extends over these positions.