and Loxodon; others, in which the number of the ridges progressively increases, are "anisomerous," and form a third natural group, namely the Euelephas or Elephas proper. The Stegodon has four species, fossil in India; and approaches the Mastodon in the form of the molars. The Loxodon includes the existing African Elephant and three fossil species, and is characterized by its distinct rhomboidal discs of wear on the grinders. Euelephas has thin-plated molars; but in some species there are intermediate stages, as regards the angular mesial expansion of the plates, between it and Loxodon.

Dr. Falconer next proceeded to review some well-ascertained mammalian faunæ localized in certain parts of Europe, where the conditions of deposit are most simple, and to apply the results to the more complex instances, where the remains of more than one distinct fauna are intermingled, or so closely deposited as to be too readily confused by collectors. With this view, the author instanced the Subapennine or pliocene deposits of the Astesan, and elsewhere in Piedmont and Lombardy, where Trilophodon Borsoni, Tetralophodon arvernensis, Loxodon meridionalis, Lox. priscus, and Euelephas antiquus, with Rhinoceros leptorhinus, Hippopotamus major, &c., are found associated together. In the Subapennine beds of the Val d'Arno, in Tuscany, Tetralophodon arvernensis and Loxodon meridionalis occur with the same Hippopotamus and Rhinoceros. Near Chartres, in France, Loxodon meridionalis accompanies H. major and Rhinoceros leptorhinus. The above-mentioned are necessarily the leading mammalian forms of the older Pliocene period. North of the Alps pliocene deposits similar to those of Italy occur in some parts of Switzerland, but they are soon overlaid towards the north by a distinct mass of erratic drift of a different age and with different mammalian remains. In the fluviatile "Loess" or "Lehm" of the valley of the Rhine, and in the Glacial Drift of the plains of Northern Germany, these post-pliocene deposits contain remains of the true Mammoth, with the tichorhine Rhinoceros, the Muskbuffalo, &c., which thus constitute the leading types of the postpliocene mammalian fauna.

On the eastern coast of England, the Crag-deposits (the Red and Norwich Crags) yield the pliocene Tetralophodon arvernensis, Loxodon meridionalis, and Euelephas antiquus; and the so-called Elephantbeds at Cromer, Mundesley, and Hasborough furnish Lox. meridionalis and Euel. antiquus, with Rhin. leptorhinus and Hip. major. These characteristically pliocene fossils, however, are occasionally intermingled with the remains of the post-pliocene Euelephas primigenius, the latter fossils having been derived from the overlying and later drift-beds, which have thus proved a fertile source of the confusion and ambiguity already referred to. To some extent,

similar conditions exist at Bracklesham Bay and Pagham Harbour, where molars of E. primigenius are found in the upper gravels, whilst remains of E. antiquus abound in the older mud-deposit, lately described in the Society's Journal by Mr. Godwin-Austen.

Dr. Falconer then considered the fluviatile deposits of the Valley of the Thames, in relation to their Elephantine remains; especially

at Grays Thurrock and Brentford. At the former place the author recognizes the true pliocene assemblage of Loxodon priscus, Euelephas antiquus, Hippopotamus major, and Rhinoceros leptorhinus; but the group of mammals found at Brentford, according to the published determinations, indicate the close proximity of both the pliocene and post-pliocene faunæ at different levels of the same section. The Grays Thurrock deposits, and the lower beds at Brentford were inferred to be of an earlier age than any part of the Boulder-Clay or Sill.

The grouping of the E. primigenius, Rhinoceros tichorhinus, Bubalus moschatus, &c., in the newer gravels of England and elsewhere was next dwelt upon, as affording an additional clue to the tracing of the several characteristic mammalian faunas over the European

area.

To the possible objection of there being too many large Proboscideans grouped in one fauna, the author replied that the bones of animals of three distinct species actually occur together in one stratum in Italy, and that six species are found in deposits of one age in the Sivalik hills.

Dr. Falconer concludes that the same mammalian fauna existed throughout the period during which both the Crag and the fluviatile beds of the Thames Valley were being deposited; and that a chronological division of the newer Tertiaries into older Pliocene, newer Pliocene or Pleistocene, and Post-pliocene is untenable; too much stress having been laid by authors upon the shell-evidence on this point. At the same time, it is not meant to be implied that all the species of the fauna ranged everywhere throughout the area: some in all probability were peculiar to the south, and others to the north.

The presence of the Hippopotamus in the pliocene deposits was pointed out as being of great importance in indicating the character of the pliocene land, which, extending between England and the Continent, must have afforded a great system of rivers and lakes, and probably had a comparatively warm temperature, as late as the deposition of the Grays beds, where also (as is well known) occur some southern freshwater shells, now extinct in England.

After some remarks on the negative evidence afforded by this mammalian fauna with regard to the supposed refrigeration of the land during the Pliocene period, Dr. Falconer reviewed the opinions of some English geologists on the physical conditions and fauna of this region during the newer Tertiary epoch, especially the views of Mr. S. Wood, Mr. Prestwich, and Mr. Trimmer; and concluded with a few remarks on the occurrence of E. antiquus in the Cefn and Kirkdale Caves, and of E. primigenius in Kent's Hole, and on the non-existence of E. primigenius south of the Alps, and its restriction in the United States of America to the Northern and Central States. In the Southern States and in Mexico a distinct fossil species, Euelephas Columbi, hitherto undescribed, occurs along with remains of Mastodon, Mylodon, Megatherium, Horse, &c.

VIII. Intelligence and Miscellaneous Articles.

NOTE ON THE QUESTION-IS THERE ANY ADVANTAGE, IN CHEMICAL DECOMPOSITIONS, IN INTRODUCING AN INDUCTION APPARATUS OF ONE WIRE IN THE CIRCUIT OF A VOLTAIC PILE? BY C. DESPRETZ.

IN IN a battery with one or two liquids in which the amalgamated zinc is scarcely, if at all, attacked by dilute sulphuric acid, when the current is not established, the loss of weight of the zinc corresponds with the oxygen of the water decomposed in the voltameter. This result shows that the pile is the most perfect of machines, when its force is measured by the decomposition of water; for in this case the effective work is equal to the motive work within a hundredth, or sometimes a two-hundredth part. The pile is supposed to be completely isolated, and the amalgamated zinc not sensibly attacked by the dilute sulphuric acid.

An experiment of M. De la Rive has shown that a pile which decomposes water very weakly, acquires the power of decomposing it in a very marked manner, if an induction apparatus be introduced into the circuit. M. De la Rive has given the name of voltaic condenser to the induction apparatus of one wire which he employed.

It has lately been asserted, that by an arrangement analogous to that of M. De la Rive, there is an actual economy in the consumption of zinc. Such an opinion can only be founded upon exact experiments. If the quantity of zinc consumed were less than that corresponding with the oxygen of the water decomposed, the union of a pile and an induction apparatus would form a more than perfect machine. Its useful effect would exceed the motive work, which would be a singular result. To settle this question, the only course is to weigh the amalgamated zinc before and after the experiment, and to compare the loss of the metal with the weight of oxygen and hydrogen of the water decomposed in the voltameter.

To make the necessary comparison, eight Bunsen's elements were arranged in two sets of four elements. This arrangement is equivalent to two elements in tension, of four times the dimension. In the circuit was placed a small induction apparatus with a single wire. When half a litre of gas (oxygen and hydrogen) was evolved in the voltameter, the loss of the zinc was 1.578 grm., on the average of five nearly concordant experiments. The average duration was an hour and two minutes.

1.578 grm. of zinc corresponds with a quantity of water represented by a volume equal to 0.8131 litre of dry oxygen and hydrogen at 32° F. and a pressure of 0.76 metre. The experiment only furnished 0.500 litre of moist oxygen and hydrogen gas at a temperature of 60° 75 F., and a pressure of 0.7435 metre. In a dry state, at 32° F. and the pressure of 0.76 metre, the 0-500 litre is reduced to 0-4531 litre. Thus the induction apparatus causes a loss of 0.36 litre, or four-ninths of the internal work, or four-fifths of the actual work obtained; in other words, nearly half the zinc is not represented by the water decomposed in the voltameter. If time were

the only object, and the zinc and acids used in the pile were regarded as negligeable matters, there would be an advantage in the use of the induction apparatus. The same pile, but without the induction apparatus, only produced half a litre of moist gas in about double the time.

The great loss of zinc here ascertained must not be attributed to the reversal of the current. The direction of the current remains the same. If each wire of the voltameter be covered with a graduated tube, the volume of one of the gases is double that of the other; the former is hydrogen, the latter oxygen. In passing the current through a solution of sulphate of copper, one electrode is covered with a coat of red copper, the other retains the colour of platinum. It is to the diversion of a part of the current by the conductor of the hammer that the greater part of the loss must be attributed.

At the commencement of the experiment the current divides into two very unequal parts,--one passes by the conductor of the hammer, and the other traverses the voltameter. This is very weak in comparison with the former; so much so that it is almost incapable of decomposing water. Nearly all the current passes by the conductor of the hammer, the resistance of the two plates of copper, of a few centimetres in length, of which this is composed, being extremely small compared with that of the voltameter. If the hammer be removed, the entire current passes into the voltameter, but the current which then traverses the pile has less intensity than when the conductor of the hanımer is closed.-Comptes Rendus, May 18, 1857, p. 1009.

ON THE SLOW ACTIONS PRODUCED UNDER THE COMBINED INFLUENCE OF HEAT AND PRESSURE. BY M. BECQUEREL. M. Becquerel has long been occupied with the slow actions produced at the surface or in the superficial strata of the globe at the ordinary temperature and pressure of the atmosphere. These actions have a chemical, electrical or mechanical origin, but the chemical cause is that which acts with the greatest efficacy. The following examples will give an idea of the influence of each of these three

causes.

When a plate of iron is exposed to moist air, it soon becomes oxidized here and there, in points where there is heterogeneity, or where foreign bodies exist. These points constitute so many voltaic couples, which assist the original chemical action. In the electrochemical reaction which takes place, water is decomposed; the hydrogen which comes in contact with the oxide combines with the nitrogen of the air or that of adherent organic matter, forming ammonia or carbonate of ammonia, which is usually found in rust. The effect is still more manifest when a fragment of charcoal, or of any other body which is a good conductor, but less oxidizable than iron, is applied to the iron plate. Copper, lead, and silver, in contact with certain solutions, produce analogous effects.

Rocks with a felspar base, or which contain alkali, when crushed and when their fragments are carried away by water and rolled in

the torrents, become decomposed by the mutual friction of their particles. M. Becquerel has proved this decomposition twenty years ago, by crushing basalt, felspar, &c. in an agate mortar in presence of water; the damp paste which is formed soon furnishes an alkaline reaction. The decomposition of the bodies pulverized is sometimes facilitated by mixing them with other bodies of which the elements are capable of acting by double decomposition upon those of the former.

Thus on triturating together in equal atomic proportions nitrate of lead and iodide of potassium, iodide of lead and nitrate of potash are obtained in a few moments. In operating with sulphate of soda and carbonate of lime, a double decomposition is also produced.

In a recent communication to the Academy, M. Daubrée has brought forward some new evidence in support of the preceding observations. He operates as follows:-Into a cask, to which he gives a rapid rotatory movement, he puts water with fragments of felspar and quartz; at the expiration of a certain time a mud produced by the trituration of the particles is deposited, and the water becomes alkaline. The felspar is consequently decomposed, at least partially.

In these investigations, M. Becquerel had hitherto operated only at the ordinary pressure and temperature of the atmosphere; in the present case he has experimented at temperatures and pressures more or less elevated, with the view of obtaining an idea of what must have taken place in the sedimentary rocks when they were covered by ejected rocks, such as granite, porphyries, basalt, &c. In the present memoir the combined influence of heat and pressure in chemical and electro-chemical actions are alone referred to. The effects resulting from mechanical actions will be treated of in a particular memoir.

The author operates as follows:-He takes a tube of 5-6 millims. in diameter and 2 decimetres in length, closed at one extremity; into this he puts the solid substance, and pours over it the solution which is to react. On the top of this some sulphuret of carbon or æther is poured; the tube is sealed up and placed in a stove heated to 212-302° F. Another tube is sometimes introduced into the principal one, containing another volatile liquid, the elementsof which are to react upon the solid body or the solution; lastly, when electro-chemical effects are in question, the apparatus destined to produce these is placed in the tube. By means of these different modes of experimentation, M. Becquerel has obtained the following products :

1. Arragonite in right rectangular prisms with two bevels at each apex, and the angles of which are measurable by the goniometer. 2. Protoxide of copper in pretty octahedral crystals.

3. Sulphurets of copper in prisms, having the aspect of the native sulphurets.

4. Sulphurets of silver and lead in lamellæ, having a metallic aspect. 5. Green carbonate of copper (malachite) and blue carbonate of copper in small nodules.

6. Metallic iodides, bromides and cyanides, insoluble and crystallized, &c.