pletely covered by the mercury and the amalgam respectively. On the mercury, place a layer one cm. thick of the zinc and mercurous sulphate paste described in 5. Both this paste and the zinc amalgam must then be covered with a layer of the neutral zinc sulphate crystals one cm. thick. The whole vessel must then be filled with the saturated zinc sulphate solution, and the stopper inserted so that it shall just touch it, leaving, however, a small bubble to guard against breakage when the temperature rises.

Before finally inserting the glass stopper, it is to be brushed round its upper edge with a strong alcoholic solution of shellac and pressed firmly in place. (For details of filling the cell, See Note B.)

NOTES TO THE SPECIFICATIONS.

(A.) The Mercurous Sulphate. The treatment of the mercurous sulphate has for its object the removal of any mercuric sulphate which is often present as an impurity.

Mercuric sulphate decomposes in the presence of water into an acid and a basic sulphate. The latter is a yellow substance-turpeth mineral-practically insoluble in water; its presence, at any rate in moderate quantities, has no effect on the cell. If, however, it be formed, the acid sulphate is also formed. This is soluble in water and the acid produced affects the electromotive force. The object of the washings is to dissolve and remove this acid sulphate and for this purpose the three washings described in the specification will suffice in nearly all cases. If, however, much of the turpeth mineral be formed, it shows that there is a great deal of the acid sulphate present and it will then be wiser to obtain a fresh sample of mercurous sulphate, rather than to try by repeated washings to get rid of all the acid.

The free mercury helps in the process of removing the acid, for the acid mercuric sulphate attacks it, forming mercurous sulphate.

Pure mercurous sulphate, when quite free from acid, shows on repeated washing a faint yellow tinge, which is due to the formation of a basic mercurous salt distinct from the turpeth mineral, or basic mercuric sulphate. The appearance of this primrose yellow tint may be taken as an indication that all the acid has been removed; the washing may with advantage be continued until this tint appears.

(B.) Filling the Cell. After thoroughly cleaning and drying the glass vessel place it in a hot water bath. Then pass through the neck of the vessel a thin glass tube reaching to the bottom to serve for the introduction of the amalgam. This tube should be as large as the glass vessel will admit. It serves to protect the upper part of the cell from being soiled with the amalgam. To fill in the amalgam, a clean dropping tube about 10cms long, drawn out to a fine point, should be used. Its lower end is brought under the surface of the amalgam heated in a porcelain dish, and some of the amalgam is drawn into the tube by means

of the rubber bulb. The point is then quickly cleaned of dross with filter paper and is passed through the wider tube to the bottom and emptied by pressing the bulb. The point of the tube must be so fine that the amalgam will come out only on squeezing the bulb. This process is repeated until the limb contains the desired quantity of the amalgam. The vessel is then removed from the water bath. After cooling, the amalgam must adhere to the glass and must show a clean surface with a metallic lustre.

For insertion of the mercury, a dropping tube with a long stem will be found convenient. The paste may be poured in through a wide tube reaching nearly down to the mercury and having a funnel-shaped top. If the paste does not move down freely it may be pushed down with a small glass rod. The paste and the amalgam are then both covered with the zinc sulphate crystals before the concentrated zinc sulphate solution is poured in. This should be added through a small funnel, so as to leave the neck of the vessel clean and dry.

For convenience and security in handling, the cell may be mounted in a suitable case SO as to be at all times open to inspection.

In using the cell, sudden variations of temperature should, as far as possible, be avoided, since the changes in electromotive force lag behind those of temperature.

II. GEOLOGY AND MINERALOGY.

1. Change of level in the West Indian Region. Mr. C. T. STIMPSON has a paper on the Distribution of the land and freshwater Mollusks of the West Indian Region, and the evidence they afford with regard to past changes of land and sea. He concludes that all the evidence of the terrestrial and fluviatile molluscan fauna of this region indicates that in the early Tertiary period, perhaps, there was a general land elevation of the Greater Antilles, and possibly of some of the adjacent area; that Wallace's theory of a land connection of the greater islands is correct; that during some part of this time a land way extended across to the continent; that the species and groups of this then connected territory migrated to some extent from one part of it to another, and that a probable connection existed over the Bahama plateau to what was at that time no doubt the island of Florida.

Jamaica, by the evidence of its land snails, stands the most isolated of any of the islands; Cuba is the next most so, while those of Haiti and Puerto Rico are much more nearly related to each other than to those of either of the first two. About 20 genera and minor groups are confined to or have their metropolis in Jamaica; a like number belong to Cuba, 7 to Haiti, and 1 to Puerto Rico.

It bears directly on this subject, that the strait between Haiti and Jamaica is deeper than that between any of the other islands,

being nearly 1,000 fathoms in depth; that the strait between Cuba and Haiti, is slightly more shallow, being only about 875 fathoms, while the one between the latter islands and Puerto Rico carries but 260 fathoms. Supposing these islands to have been united at a former time, then, during a period of gradual subsidence, Jamaica would be separated sometime before the rest of the Antillian island would be broken up; then Cuba would be isolated, while Haiti and Puerto Rico would remain united for a longer time. The distribution and character of the land-snail faunas of these islands agree exactly with just what would be the result of such a subsidence and separation.

2. Glacial phenomena Northwest and West of Hudson Bay.MR. J. B. TYRRELL, of the Canada Geological Survey, concludes, after an examination of the region on the northwest and west of Hudson Bay, and especially from the direction of the glacial scratches, that within a comparatively short distance of the northern portion of the bay, there was "one of the great gathering grounds for the snow of the Glacial period;" and that from the ice-plateau thus made, the movement of the ice was eastward, into the Hudson Bay depression, northward toward the Arctic Ocean, and a long distance westward toward the Mackenzie River. There was also a southward movement "toward the great plains. At this time Hudson Bay was probably to a great extent open water."

After the recession of the ice from the lower country, the land was about 400 feet below its present level. There are terraces at different heights about the lakes. Those of Aberdeen Lake have the heights 290, 220, 180, 150, 105, 90 and 60 feet above it. Similar terraces are found in favorable localities all along the shores of Hudson Bay.

3. Faults of post-Glacial origin.-In Bulletin XII of the Natural History Society of New Brunswick (p. 34) Dr. G. F. MATTHEW describes small faults observed by him over a considerable area in the ledges of slate near St. John. The relations of the faults to the glacial striæ indicates that they are post-Glacial. Their courses vary; but at St. John the greatest throws and the most frequent have a northeast to southwest course, and the more the joints depart from this course the less is the displacement; rarely any occur at right angles to it. The displacements observed are mostly between half an inch and ten inches. Dr. Matthews regards it as probable that the faulting is due to lateral pressure from the southeast.

4. Pre-Cambrian Radiolarians.-The paper of L. CAYEUX, on Radiolarians in the pre-Cambrian rocks of Brittany (Bull. Soc. Géol. de France, 1894, p. 197) is accompanied by a plate giving figures of 45 of the forms observed. The figures appear to sustain fully the author's conclusion as to the Radiolarian character of the organisms. He describes them as having generally a distinct outer shell, which is pierced by pores. The age of the rocks is pronounced pre-Cambrian by Barrois. They are quartzites,

and compact siliceous slates or phthanite. In a section near Pléboule, the beds are represented by Barrois, as standing nearly vertical and as conformable with beds of argillyte, granulitic gneiss, hornblendic schist, and other rocks. Pebbles of the Radiolarian rock are found in the Cambrian conglomera of Montfort and Erquy and in pre-Cambrian conglomerates at the base of the "Phyllades de Saint Lo;" and from this the conclusion is drawn that the Radiolarian beds are at least pre-Cambrian.

5. Geological Survey of Alabama: 1894, Report on the Geology of the Coastal Plain of Alabama by E. A. SMITH, L. C. JOHNSON and D. W. LANGDON, Jr., with contributions to its Paleontology, by T. H. ALDRICH and K. M. CUNNINGHAM, with illustrations, pp. i-xxiv, 1-759, 1894.-The nucleus of the present report was published in 1887 as Bulletin No. 43 of the U. S. Geological Survey, but the present work contains considerable new matter and a revision of the Bulletin in the light of later discoveries.

In the Tertiary part, upon the work of Mr. Johnson, the horizon of the "Grand Gulf" formation has been shown to be of Miocene age, and a new formation at its top, has been described and its age determined to be also Miocene, by Dr. Dall.

The "Tuscaloosa " formation which was described in the Bulletin No. 43, but then only doubtfully referred to some place in the Cretaceous, and since then referred to the lower Cretaceous,* is shown by its fossil plants, discovered in 1892 and identified by Dr. Ward, to be nearly equivalent to the Amboy clays (= Raritan group, Dakota Epoch), the lower member of the Upper Cretaceous. The specimens identified are of species described from the Amboy clays, Dakato group, and Cretaceous of Greenland. The species of fossils described by Mr. Aldrich are from the (Midway) Clayton Tertiary, of the lowest beds of the Eocenc.

H. S. W.

6. Paleozoic Corallines.-The first of Paleozoic Algæ of the group of Corallines has been described and figured by R. P. WHITFIELD in the Bulletin of the American Museum of Natural History, vol. vi, p. 351, 1894. He names the single species thus far discovered Primicorallina trentonensis.

7. Lehrbuch der Petrographie von Dr. FERDINAND ZIRKEL. Zweite gänzlich neu verfasste Auflage. Dritter Band. 833 PP. large 8vo. Leipzig (Wm. Engelmann).-The third volume of this exhaustive work appeared near the close of the past year. The earlier volumes have been already noticed in this Journal and the minute and at the same time comprehensive character of the whole has been dwelt upon. The opening part of this third volume discusses the rocks containing a lime-soda feldspar with nephelite or leucite; those with nephelite, leucite, or melilite without feldspar, and those containing no constituent corresponding to feldspar. The crystalline schists are then taken up, also the crystalline rocks of simple mineralogical character; then

* Dana's Manual of Geology, 4th edition, 1895, p. 816.

follows the discussion of the clastic rocks, that is, the conglomerates, breccias and tuffs of rocks of different types; then the sandstones and sedimentary deposits and finally kaolin, clay, marl, etc. The index for all the three volumes, which closes the work, contains rock-names only and is so brief as to seriously impair the usefulness of the whole. The author is to be heartily congratulated in the completion of his work; the many workers in this department of science will not fail to estimate aright the value of his arduous labors.

8. Chemical Contributions to the Geology of Canada from the laboratory of the Survey; by G. CHRISTIAN HOFFMANN (Annual Report, vol. vi, 1892-93, Part R).-Mr. Hoffmann's report contains, besides analyses of fuels, assays of ores and other matters of economic bearing, also a number of points of mineralogical interest. Among these we note the identification of the following minerals, of several of which analyses are given: löllingite from Galway, Peterborough County, Quebec, containing nearly 3 per cent of cobalt and 0.8 per cent of nickel; strontianite from Nepean, Carleton County, Ontario, where it occurs in veins of some extent; also the same mineral from near the Horsefly river, Cariboo district, British Columbia; native iron in minute spherules occurring with the perthite of Cameron, Nipissing, Ontario; pyrargyrite from the Dardanelles claim near Bear Lake, West Kootanie, British Columbia; anglesite from the Wellington mine in the same region; calamine from the Skyline claim, near Ainsworth, West Kootanie; altaite from Liddle Creek, West Kootanie; arsenolite with native arsenic from Watson Creek, British Columbia; cinnabar, perhaps in a large deposit, near the mouth of Copper Creek, Kamloops Lakes, British Columbia.

9. Meteoritenkunde; von E. COHEN. Heft 1. Untersuchungsmethoden und Charakteristik der Gemengtheile, 340 pp. 8vo. Stuttgart, 1894 (E. Schweizerbart'sche Verlagshandlung — E. Koch). This volume forms the first part of a comprehensive work on meteorites, which will be warmly welcomed by all interested in this subject. Such a work is much needed at the present time. In recent years, especially during the past two decades, the literature of the subject has increased remarkably, many investigations after the improved modern methods of research have been made of recent, as of earlier, falls, and the collation and digestion of this vast amount of new material have become a matter of the highest importance. This work obviously involves great labor and calls for the knowledge and experience which are possessed in a high degree by the author.

The present part, which is chiefly devoted to a description of the mineral constituents of meteorites, will be followed by others. discussing the structure, external and internal, of meteorites, their classification and finally the phenomena of fall and the hypotheses advanced to explain their nature. logical side of the subject has been performed with care and The work on this minerathoroughness and the completion of the whole will be looked for with interest.