by us. If we alone were to support this accident, we would have a strong party to combat, and our assertion might be more than counterbalanced by their complete denial; but we have fortunately an arbiter in this case they cannot refuse, having formerly accepted his evidence. Count Munster wrote, March 1828, to Kefferstein, that he had observed among the Gossau fossils, young specimens of the Gryphæa columba of the greensand, and his letter was published in the Geological Gazette, page 99 of the 6th vol. part 2d, of the Teutchland Geognostisch-Geologisch dargestellt. published in 1829 by Kefferstein. In my collection, I have that fossil in the state described by Count Munster, and Mr Lill has it also. This is a case in which we may apply the judicious observations of De France, upon the variations which a species may undergo, or upon the different states in which a fossil may have been petrified in various localities. We trust that this explanation will dissipate every doubt regarding this point, and that my opponents will also be forced to place in the tertiary formation this fossil, so characteristic for the greensand, or they must change their opinion. Besides, M. de France recognised in my collection another small species of gryphite, which he has from other chalk localities.

Lastly, we come to the singular reproach made to us, that, in order to determine the age of the Gossau deposite, we had recourse to the characters presented by similar patches found here and there in the Austrian Alps. Our mode of proceeding, whatever our authors may say to the contrary, is strictly logical. It was only necessary to be certain that the localities we compared were geologically identical, on which point there remains not a shadow of doubt in the minds of those geologists acquainted with the country, viz. Messrs Partsch and Kefferstein. Unfortunately our authors visited only Gossau, but they are not from this circumstance to deny that similar deposites may not exist elsewhere. Indeed, such an assumption would be in opposition to their own theory, according to which, this formation should have been pretty generally distributed and divided into isolated masses by the upheaving of the Alps. If they had seen, as our excellent friends, Mess. Partsch and Kefferstein, and we also, the localities of Grünbach, Hieflau, Gams,

Hinter Laussa, Launz, &c., they would not have written that "we had no right to transport the reader over 150 miles of alpine limestone, and then to assert, that at Grünbach, Piesting, &c., the same deposite as that at Gossau contains belemnites and certain other secondary fossils."-(P. 111.)

When we find again at Grünbach, at Piesting, &c., the same rocks as at Gossau; when we see these rocks in a similar position; and when three geologists recognise in these beds a great many of the same fossils as at Gossau; does it not seem that we have a right to speak of that deposite when we are endeavouring to classify the problematic deposite of Gossau ? and we ask if it be allowed to say, as those gentlemen do, that such an argument is nothing better than a direct inversion of the rules of induction? (p. 111.)

The hurry of writing is the only excuse we can offer for such an expression of opinion; for what would our critics say, if we, in their classification of the patches of greensand in the southern parts of England, would deprive them of the liberty of placing under one head all the fossils of the greensand of the Isle of Wight, Dorsetshire, Hampshire, and Kent? They would certainly consider me a strange logician. Besides, in the case of Grünbach, these gentlemen are the more to blame, as M. Kefferstein had already, in 1828, in the 5th vol. p. 446, of his Teutchsland Geognostisch-geologisch dargestellt., well described the locality of the Wand, and had well identified by means of the fossils the deposites of Grünbach and Gossau. If we find belemnites, litulites, anachites, &c., at Grünbach, it appears to us, after this long discussion, that we should mention the fact, and make use of it to establish more certainly that the Gossau rocks are not tertiary, but secondary. We do not see any thing extraordinary in the circumstance, that, in the same formation, some fossils may be awanting in one locality, but present in another, as is the case at Sonthhofen and the Kressenberg. The deposite of Gossau also offers similar and striking examples; thus, at Gossau, there is a pretty large and abundant ampullaria or natica, the place of which at Gams appears to be replaced by a pretty large species of tornatella, and at Wand both fossils occur in great abundance.

We have now finished our examination of the memoir of Messrs

Sedgwick and Murchison, and we hope it has been shewn that no tertiary deposites (at least as they are understood at present) exist in the northern Austrian Alps, and that the tertiary rocks of the Austrian flat land do not ascend into the transverse valleys of the Alps. Besides, we think we have shewn that the Jura limestone, composing the alpine calcareous chain, is covered in different places, as in the French and Swiss Jura and in the German Alps, by isolated patches of rocks belonging to the greensand and the chalk. If these last deposites do exist on the borders of the Alps, we positively deny that there is a transition from that formation to the tertiary one, and we defy any one to prove this, if we admit the total absence of tertiary rocks in the middle of the Alps. We might conclude here, and await the answer of our opponents; but we feel it right, as some observers, not aware of the extent of our investigations, might suppose that our statements were founded on few facts, to state the extent of our travels, which were continued for several years in the Alps. Messrs Sedgwick and Murchison also felt it necessary to enumerate on how many excursions and sections their ideas were based.

Since 1821, we have visited in our various journeys, first the whole of the northern calcareous and primary chains of the Alps from Feldkirch in the Voralberg to Eisenerz and Somering in Styria; the country south of the Lofer in the Tyrol alone remained unexplored by us. On the other hand, we made a journey for the sole purpose of following step by step the northern-foot of the calcareous secondary chain, in order to study thoroughly the range of the secondary sandstone, and its contact with the alpine limestone and the molasse. That journey was performed without interruption from Sonthhofen in Bavaria to Vienna in Austria, and during it we entered in succession a great number of the valleys. Since that time, we have added to this survey a fortnight's stay at two different times in the Allgau, an excursion in the Voralberg, and we have been so circumstanced as to continue similar observations in various places in Savoy and Switzerland. In order to become well acquainted with the alpine structure, sections throughout the whole chain were necessary; and hence we made it our business to examine, at various times, nearly the whole of the passes that cross the range.

OCTOBER-DECEMBER 1830.

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ginning on the west and proceeding to the east, we crossed the Alps successively in the valley of the Rhine, in the Voralberg, in the Allgau, along the Lech, between Fussen and Nassereit; between Seefeldt and Amergau; between Seefeldt and Benedictbeuren; along the Inn, to the southern Tyrol over the Brenner; partly to the south of the Chiemsee lake, in the valley of the Bavarian Traun, of the Saal, and the Achenbach; along the Salza from Salzburg to Werfen; from Salzburg to Liezen; from that place to St Gallen; from Steyer to Eisenerz; from Waidhofen to Eisenerz; from Gaming by Neuhaus, Palfau, and Gams, to Eisenerz; from Neuhaus to Mariazell; from St Polten to Seewiesen by Maviazell; from St Polten to Baden and Vienna; and from Vienna to Gratz and to Croatia, through the Matzegebirge. The collections of rocks made at all these and the following localities I have preserved, and will be delighted to explain them to geologists.

In the southern Alps, we have visited in the same way all the southern border of the calcareous alpine chain from Bergamo to Conegliano. We have ascended along the valleys of the Brenta, seen those of Fassa, of the Cordevole, of the Piave, of the Fella, and of the Drave. Lastly, we crossed the Leoben; we visited Bleiberg, Raibel, Laibach, Idria, the valley between Idria and Lack, Trieste, and Fiume. We went over the greatest part of Istria to its southern termination. We entered into Dalmatia, crossed the Capellen-Gebirge from Buccari to Carlstadt, and, after an excursion farther east, we followed the road from that town to Laibach. We may add, that, well informed of all the difficulties in classifying the Gossau deposite, we last year made a journey through the Austrian Alps, for the sole purpose of studying thoroughly all the well known localities where such rocks occur, and of establishing a reasonable classification, and describing each locality. After these journeys, continued during nine years, for the study of the alpine limestone chain in Germany, we thought that we might, assisted by our friends, attempt to lay before the geological public the conclusions explained in this paper and elsewhere. In what relates to the difference of our opinion from that of Messrs Sedgwick and Murchison, the public will now be able to judge; and, we trust, that they will ere long favour us with an answer, written with that calmness and spirit of concord which ought always to accompany scientific discussions.

On the Chemical Constitution of Brewsterite. By ARTHUR CONNELL, Esq. F. R. S. E. Communicated by the Author.

THIS mineral was first characterized, from its crystalline form, as a distinct species by Mr Brooke, who also gave it its present name *.

It would appear that, some years ago, a specimen of the mineral was sent by Dr Brewster to Berzelius, for the purpose of being analyzed; and that Berzelius wrote back in answer, that it had been already analyzed by Retzius, conformably to the

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formula S3 + 4 A S3 + 8 Aq, and called by him Prehniti

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form Stilbite†. This formula, or the corresponding chemical one, has been retained by Berzelius; and I am not aware that any other statement respecting the constitution of the mineral has been given to the public. The locality of the mineral analyzed by Retzius is not stated. The formula of Berzelius gives §,

In a former notice on this subject ||, I shewed, from an examination of some pure crystals of Brewsterite from Strontian in Argyllshire, that it contained strontia and baryta, and no notable quantity of lime. I also shewed that it contained no alkali, and concluded that the formula of Berzelius did not apply to the mineral, at least when derived from the above locality, unless the formula and composition could be accommodated to one another by the aid of the doctrine of replacement.

It became a matter of some interest to establish by a regular

Edin. Phil. Journal, vol. vi. p. 112.

+ Edinb. Jour. of Science, vol. iv. p. 316.

‡ Die Anwendung des Löthrohrs, 2te Auf. S. 168.

§ This calculation is made by the atomic weights of Berzelius. All the subsequent calculations of formulæ are made by those of Dr Thomson. || Edinb. New Phil. Jour. No. 16. p. 355.