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Jnne 13, 1895.

The LORD KELVIN, D.C.L., LL.D., President, in the Chair.

His Royal Highness the Duke of Saxe-Coburg-Gotha (elected March 16, 1882) was admitted into the Society.

A List of the Presents received was laid on the table, and thanks ordered for them.

The following Papers were read :

I. "On the new Gas obtained from Uraninite. Fourth Note." By J. NORMAN LOCKYER, C.B., F.R.S. Received May 28,

1895.

Continued experiments on the gases obtained by heating the minerals bröggerite and euxenite in vacuo have revealed the presence in the spectrum of an important line in the infra-red. By comparisons with the solar spectrum in the first order grating spectrum, the wavelength of the line has been approximately determined as 7065. There can be little doubt, from the observations which have been made, that this new line is coincident with a chromospheric line which occurs in Young's list, having a frequency of 100, of which the wave-length on Rowland's scale is stated to be 7065.5.

It follows therefore that, besides the hydrogen lines, all three chromospheric lines in Young's list which have a frequency of 100 have now been recorded in the spectra of the new gas or gases obtained from minerals by the distillation method.

These are as follows:

7065.5

5875.98

4471.8

The wave-lengths of the lines are in Rowland's scale, as given in Scheiner's "Astronomical Spectroscopy."* In a partial revision of his chromospheric list, Professor Young gives the corona line 5316-79 as also having a frequency of 100 in the chromosphere, but, up to the present, this line has not been observed in the laboratory.

Frost's translation, p. 184.

II. "On the New Gas obtained from Uraninite. Fifth Note." By J. NORMAN LOCKYER, C.B., F.R.S. Received May 29, 1895.

In a former communication I pointed out the spectroscopic evidence, furnished by the isolation of lines in certain minerals, which indicates that the complete spectrum obtained when bröggerite is submitted to the distillation method is produced by a mixture of gases.

In order to test this view, I have recently made some observations, based on the following considerations.

(1.) In a simple gas like hydrogen, when the tension of the electric current given by an induction coil is increased, by inserting first a jar, and then an air-break into the circuit, the effect is to increase the brilliancy and the breadth of all the lines, the brilliancy and breadth being greatest when the longest air-break is used.

(2.) Contrariwise, when we are dealing with a known compound gas; at the lowest tension we may get the complete spectrum of the compound without any trace of its constituents, and we may then, by increasing the tension, gradually bring in the lines of the constituents, until, when complete dissociation is finally reached, the spectrum of the compound itself disappears.

Working on these lines, the spectrum of the spark at atmospheric pressure, passing through the gas, or gases, distilled from bröggerite, has been studied with reference to the special lines C (hydrogen), D3, 667, and 447.

The first result is that all the lines do not vary equally, as they should do if we were dealing with a simple gas.

The second result is that at the lowest tension 667 is relatively more brilliant than the other lines; on increasing the tension, C and D3 considerably increase their brilliancy, 667 relatively and absolutely becoming more feeble, while 447, seen easily as a narrow line at low tension, is almost broadened out into invisibility as the tension is increased in some of the tubes, or is greatly brightened as well as broadened in others (fig. 1).

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FIG. 1.-Diagram showing changes in intensities of lines brought about by varying the tension of the spark. 1. Without air-break. 2. With air-break.

The above observations were made with a battery of five Grove cells; the reduction of cells from 5 to 2 made no difference in the phenomena except in reducing their brilliancy.

Reasoning from the above observations, it seems evident that the effect of the higher tension is to break up a compound, or compounds, of which C, D, and 447 represent constituent elements; while, at the same time, it would appear that 667 represents a line of some compound which is simultaneously dissociated.

The unequal behaviour of the lines has been further noted in another experiment, in which the products of distillation of bröggerite were observed in a vacuum tube and photographed at various stages. After the first heating, D, and 4471 were seen bright, before any lines other than those of carbon and hydrogen made their appearance. With continued heating, 667, 5016, and 492 also appeared, although there was no notable increase of brightness in the yellow line; still further heating introduced additional lines 5048 and 6347.

These changes are represented graphically in the following diagram (fig. 2).

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FIG. 2.-Diagram showing order in which lines appear in spectrum of vacuum tube when bröggerite is heated.

It was recorded further that the yellow line was at times dimmed, while the other lines were brightened.

In my second note, communicated to the Royal Society on the 8th instant, I stated that I had never once seen the lines recorded by Thalén in the blue, at X 4922 and 4715.

It now seems possible that their absence from my previous tubes was due to the fact that the heating of the minerals was not sufficiently prolonged to bring out the gases producing these lines.

It is perhaps to the similar high complexity of the gas obtained from clèveite that the curious behaviour of a tube which Professor Ramsay was so good as to send me, must be ascribed. When I received it from him, the glorious yellow effulgence of the capillary, while the current was passing, was a sight to see. But after this had gone on for some time, while the coincidence of the yellow line with D of the chromosphere was being inquired into, the luminosity of the tube was considerably reduced, and the colours in the capillary

and near the poles were changed. From the capillary there was but a feeble glimmer, not of an orange tint, while the orange tint was now observed near the poles, the poles themselves being obscured by a coating on the glass of brilliant metallic lustre.

After attempting in vain for some time to determine the cause of the inversion of D, and 447 in various photographs I had obtained of the spectra of the products of distillation of many minerals, it struck me that these results might be associated with the phenomena exhibited by the tube, and that one explanation would be rendered more probable if it could be shown that the change in the illumination of the tube was due to the formation of platinum compounds, platinum poles being used. On May 21st I accordingly passed the current and heated one of the poles, rapidly changing its direction to assure the action of the negative pole, when the capillary shortly gave a very strong spectrum of hydrogen, both lines and structure. A gentle heat was continued for some time and apparently the pressure in the tube varied very considerably, for as it cooled the hydrogen disappeared and the D3 line shone out with its pristine brilliancy. The experiment was repeated on May 24th and similar phenomena were observed.

III. Further Observations on the Organisation of the Fossil Plants of the Coal-measures. Part III. Lyginodendron and Heterangium." By W. C. WILLIAMSON, LL.D., F.R.S., Emeritus Professor of Botany in the Owens College, Manchester, and D. H. SCOTT, M.A., Ph.D., F.R.S., Honorary Keeper of the Jodrell Laboratory, Royal Gardens, Kew. Received May 14, 1895.

(Abstract.)

Introduction.

The two genera, Lyginodendron and Heterangium, are among the most interesting and at the same time the most puzzling representatives of the Carboniferous flora. Although we are still without any satisfactory evidence as to the reproductive organs in either genus, yet the organisation of their vegetative members is preserved with such completeness and perfection as to show that these fossils present a combination of characters such as exists in no living group of plants.

The evidence afforded by the vegetative characters clearly points to a position intermediate between ferns and Cycades.

I. LYGINODENdron.

Lyginodendron oldhamium, Will.,* is one of the commonest fossils preserved in the calcareous nodules of the Lancashire and Yorkshire coal-measures, and has also been found in those of Germany and Austria. A renewed investigation, with the aid of numerous additional specimens, has enabled us to clear up many doubtful points in the structure of the plant, and to give for the first time a complete account of all its vegetative organs.

A. The Stem.

1. General Structure.--The middle of the central cylinder or stele is occupied by a parenchymatous pith. Surrounding this is the primary wood, which usually forms a ring of from five to eight distinct strands. Beyond this we find, in all but the youngest specimens, a broad zone of secondary wood, then the cambium, and next the phloëm. The whole stele is bounded by a well-marked pericycle. The inner cortex is mainly parenchymatous, while the outer zone consists of alternating strands of fibres and parenchyma, constituting the wellknown "dictyoxylon cortex " of Count Solms-Laubach.

The pericycle and cortex are traversed by the leaf-trace bundles, which alternate with the perimedullary xylem-strands.

2. Course of the Vascular Bundles.—We have obtained direct proof that the perimedullary strands of xylem form the downward continuation of the bundles which pass out into the leaves. Thus the entire bundle-system of the stem is built up of the leaf-traces. Each leaftrace extends through at least ten internodes; five internodes are traversed while it is passing through cortex and pericycle, and five more after it has reached the periphery of the pith. On entering the pith the trace turns aside in the kathodic direction, and unites with the adjacent perimedullary strand on that side. We thus see that these strands are sympodial bundles, made up of the united lower portions of adjacent leaf-traces.

In the upper part of its course, each leaf-trace consists of two bundles, which unite into one in passing through the pericycle.

The phyllotaxis was usually two-fifths, but in the smallest stems was probably one-third.

3. Structure of the Vascular Bundles.-The preservation is so good that we have been able to determine with certainty that the bundles in the stem were normally collateral, having xylem on their inner, and phloëm on their outer side. As they passed out into the leaves

* See Williamson, "Organisation of the Fossil Plants of the Coal-measures, Part IV," Phil. Trans.,' 1873; Part VI, Phil. Trans.,' 1874; Part VII, ‘Phil. Trans.,' 1876; Part XIII, 'Phil. Trans.,' 1887; Part XVII, 'Phil. Trans.,' 1890.

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