Изображения страниц

and stated their results, and the inferences they drew therefrom, with the charming naivetè, and modesty, of their illustrious leader.

Archæan Geology, as the study of the lower formations antecedent to the Cambrian has been termed, has attracted great notice recently. Professor Sterry Hunt proposed the following classification of these rocks in America, where they are enormously developed :

1. KEWEENIAN, or Copper bearing Series of Lake Superior.


3. MONTALBAN, or Mica Schist Series.

4. HURONIAN, or Green Mountain Series.

[blocks in formation]

and on his recent visit to England he stated that he had identified the Pebidian of Dr. Hicks with his No. 3 and part of No. 4; Dr. Hicks' Arvonian with the lower part of No. 4 ; and the Dimetian and Lewisian with the Laurentians of Canada. These ancient formations cover the greater part of Anglesea, and it is to be hoped, that, during the present session, we may be favoured by some of our members with papers giving the results of the most recent researches in them.

Much new light has also been thrown upon the relations of the members of the Trias, and Dyas, (or Permian), and their classification, and, as the former system so largely constitutes the solid geology of our district, the subject might be very profitably discussed by us, and a paper on this subject would be a very desirable addition to our coming transactions.

The International Geological Congress has recommended the following terms for universal adoption :—

[blocks in formation]

They have also recommended a scale of colours, based on the solar spectrum, beginning at the Violet end, for the Trias, and finishing with the Yellows, for the Tertiaries, the colours for the Paleozoic groups being reserved for consideration by the Map Committee: and they have further decided to publish a Geological Map of Europe, on a scale of about twenty-five miles to an inch. The mere finding of terms appears to be but a small matter, but the proposed colours offer no advantage over the chaste and elegant ones adopted by our own national survey, and for our purposes, concerned as we chiefly are, with districts already mapped by that survey, the Speaker suggested that we cannot do better than adhere to those hitherto adopted.

Geological Literature has been enriched by several notable works published since our last annual meeting. Of the long promised work by Mr. Bauerman on Mineralogy, the first part, dealing with Crystallography and the Physical and Chemical properties of Minerals has appeared. It is a very complete treatise on these branches of the Science, and the second part, on Descriptive Mineralogy, will be awaited with great interest. Professor Judd has issued his work on Volcanoes which amply justifies the high expectations to which his previous papers on this subject had given rise; and certainly no Geological library should be without this book. There have also been published De Rance's "Water Supply of England and Wales;" "Harrison's "Geology of the Counties of England and Wales," "Heddle's "Geognosy and Mineralogy of Scotland," (several of the northern counties have been issued), Ball's "Economic Geology of India," and the "Life, Letters, and Journals of Sir Charles Lyell," with others, of which time does not permit so much as to give the titles. Some of those named have already been added to our Library, and it is hoped that by the liberality of our members, and friends, we may soon possess them all.

In concluding, the Speaker pointed out that the success hitherto attained by this Association, was due to the cordial co-operation of the Members in supporting the Officers in their sometimes arduous labours, and to the spirit and enthusiasm

of those Members especially who had brought forward such a varied, able, and interesting, series of papers, and he urged that it is only by a continuation of this earnest working spirit, that the future success of the Association can be assured, and that the coming session, when looked back upon from the standpoint of our next Annual Meeting, may afford as good ground for congratulation as does that which is now "numbered with the years that are told."

Abstract of a Paper read





The artificial production of the Diamond having been referred to in a Paper recently read before this Association,* the following account of some experiments bearing upon the subject, performed by Professor W. M. Logeman, of Haarlem (the father of the present writer), may be of interest.

Those who have read the descriptions of the experiments of Ganal, Mactear, and Hannay, are not likely to doubt the possibility of "making diamond." There is, however, a great difference between making diamond (i.e. the material), and making diamonds (i.e. crystals of carbon of such a size as to possess a commercial value.) Until recently most persons were disposed to look upon attempts to produce diamond much in the same light as upon the old experiments of alchemists to make gold. In the former case it is not a question of transforming one element, or reputed element, into another, but merely of causing carbon, which exists abundantly in one form, to assume another-rarer-molecular structure. Looked at from this point of view it would seem that, instead of being impossible, the experiment ought not to present any great difficulties. However, the peculiar chemical and physical properties of carbon are such that in practice these difficulties are almost insurmountable.

*" Diamonds,"

By Charles E. Miles. Vide Transactions.

Vol. ii. page 92.

There are various methods of causing crystallization, for instance: :

FIRST.-Solution of the material to be crystallized in a

liquid and slow cooling, or evaporation of the solvent.

This method fails in the case of carbon, because there is no liquid known which will dissolve ordinary carbon without combining chemically with it.

SECOND.-Melting of the material and slow cooling.

Carbon, no doubt, is molten in the electric arc, as the carbon points in the lamps clearly show; but the essential condition of success, slow cooling, cannot be fulfilled.

THIRD.--To evaporate the molten material, and allow the vapour to recondense against a cooler surface.

Iodine and sulphur can easily be made thus to yield crystals. On one occasion after an experiment with an arclight, which had lasted so long that the surrounding globe had become, in consequence, unusually hot, my father noticed among the amorphous carbon which covered the glass many hard and sharp grains. These were collected, and showed themselves to the naked eye to be minute white or grey specks. It was found, however, impossible to separate them from the adherent black particles of carbon. The microscope showed nothing definite, and the only ground for supposing these bodies to be diamond" was that, when rubbed between two glass plates, they scratched these very clearly.

FOURTH.-Slow evaporation by electro-lysis from a chemical combination.

This was Ganal's method in 1850, and was also the way my father attempted in the following experiment.

The apparatus of Donny and Mareska for the liquefaction. and solidification of carbonic acid had been recently acquired by the Teyler Museum, at Haarlem, and permission was readily granted by the Director, Professor van Breda, to use the

apparatus in order to subject some liquified-carbonic acid to slow electro-lysis by means of two platina wire electrodes. Great difficulties were met with in the preparation of glass tubes through the walls of which wires had to be fixed and the glass molten to close around them strongly enough to resist the pressure of the partially liquified carbonic acid at a temperature of 15° C. After repeated failures two such tubes were prepared; one was placed vertically under the leaden bellshaped cover and the two wires brought into connection with an electric battery of 6 Daniel cells. The needle of a rheoscope showed that, although a bad conductor, the carbonic acid did allow a current to pass, which soon began to diminish (i.e., began to experience greater resistance). An explosion followed, which concluded that experiment. A second tube

met with the same fortune, and a third was prepared of narrower bore and with thicker walls, which promised greater success. The current sent through it was of only one cell. In this tube the resistance was found to be evidently increasing and after some eight hours the inner resistance equalled the force of the cell: no current did pass. The apparatus was then left undisturbed until the next morning. On being then examined, and the leaden cover removed, the tube was discovered whole, containing liquid carbonic acid in the lower half, and there was no evidence of anything having taken place. It seemed likely that one of the electrodes had been covered with a thin layer of crystallized carbon-for it was clear that some resistance, which did not previously exist, had arisen, but inspection through the glass showed nothing. It was therefore decided to break the tube, but upon this being attempted, the tube exploded and broke into small fragments. The electrodes were bent and almost broken. The negative one appeared to sight and touch somewhat smoother and more shining than the other. Both were immersed in diluted sulphuric acid, and connected with a battery of 3 cells. What had been the positive one soon covered itself with small bubbles of gas, but the negative one only on those places which had been bent. This clearly pointed at the wire having been covered

« ПредыдущаяПродолжить »