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posited from aqueous solution, though occasional impregnation of previously existing rocks by percolation was by no means unlikely.

On the Properties and Composition of the Cocoa Leaves.

By Professor JOHNSTON, M.A., F.R.S. L& E.

After describing the remarkable physiological properties of the leaves of this plant, the author explained that they yield to æther a peculiar volatile resinous substance possessed of a powerful odour, in which the peculiar virtues of the leaf are supposed to reside. The plant is as yet to be obtained in too small quantity in this country to admit of a complete chemical examination of the substances which the leaves contain.

On the Causes, Physical and Chemical, of Diversities of Soils.
By Professor JOHNSTON, M.A., F.R.S. L. & E.

In this paper, the author, assuming as a general rule that the materials of which soils are composed are derived from the rocks on which they rest, and that therefore the agricultural is very materially dependent upon the geological character of a country, showed how physical and chemical influences subsequently interfered almost everywhere materially to modify the agricultural indications of geology.

I. Among physical influences, he showed

1. How the flatness of a country and the absence of outfalls causes the rain-water to stagnate, covers it with bogs, and obliterates the agricultural influence of the rocks beneath.

2. How high and sloping lands yield their finer particles to the rains which fall upon them, to be borne down to lower levels. Thus the granites yield their felspar and the red sand their fine marls, and thus from the debris of the same rock, often extending over large areas, regions of very different soils are established.

3. How along the line of ancient or existing water-courses, a ribbon of varying breadth is found in every country, upon which the soils consist of these fine matters separated and sorted by the action of water, and possessing agricultural characters more or less different from those which naturally belong to the geological formations on which they rest. And these differences become the more marked along the courses of great rivers, or of such as descend from great distances, and flow through various geological formations, of which they wash out, bear away, and intermingle the debris. 4. How along the shores of the sea, successive elevations of the sea establish upon the same geological formation belts of sand, very unlike in agricultural value.

These remarks were illustrated by an agricultural map of New Brunswick; and the conclusion the author endeavoured to establish was, that the physical geography, the hydrography, and periods of elevation of a country were scarcely less important than its geological structure in determining the agricultural value of its surface.

II. Among important chemical influences, the author mentioned as of much weight1. The production of acid matters in the soil wherever vegetation existed. Such acid matters are constantly produced wherever vegetable substances undergo decay in the surface soil, and sometimes in such quantity as to render the soil sour to test paper. These acids are washed downwards by the rains which sink into the soil. As they descend, they dissolve out of the soil such earthy substances-lime, alumina, oxide of iron, &c.-as they are capable of taking up, and these they bear away with them in a fluid form wherever they flow. Thus they gradually establish differences, both chemical and physical, between the upper and under portions of the drift or rocky debris from which the soils are formed, and at last render the uppermost layers in which the plants grow, totally different in its agricultural character from that which belongs to the original unaltered materials themselves. Hence the thin non-calcareous soils which cover the chalk and other limestone format ions-the constantly recurring necessity for the re-addition of lime to cultivated land-the benefits from bringing up new soil from beneath, and of many other agricultural practices.

2. The firing of the forests in new countries, where hot summers scorch vegetation and raging fires spread their devastations sometimes over thousands of square miles. Such fires are almost invariably attended by strong winds, which bear away the ashes of the burning wood to immense distances. Thus in a single day all that the trees have been extracting from the soil during a whole half-century is swept away; even the surface soil itself is sometimes scorched and swept bare. After a time a new

vegetation springs up to suffer the same fate; it may be in another half-century, and thus a constant chemical robbing and exhaustion of the soil takes place. Thus barrenness at last overspreads regions which are naturally fertile, and which rest upon rocks, the debris of which naturally yield the materials of a rich agricultural surface. Such results of burning are often observed in North America, and the author advanced the fact as one of personal observation which he had been led thus chemically to explain. The general conclusion to which the author arrived was this, that while the geology of a country has certain broad and undoubted direct relations to its agricultural value, yet when we follow the subject into detail, these relations become more and more indirect; other influences, chemical and physical, come into play and assume the character of leading agencies, and as we investigate them more and more closely, we almost seem to lose sight of geology altogether.

Description of some new kinds of Galvanic Batteries, invented by M. KUKLA of Vienna.

The combination used in one of these is antimony, or some of its alloys, for a negative plate, with nitric acid of specific gravity 14 in contact with it, and unamalgamated zinc for a positive plate, with a saturated solution of common salt in contact with it. A small quantity of finely powdered peroxide of manganese is put into the nitric acid, which is said to increase the constancy of the battery.

The alloys of antimony which M. Kukla has experimented with successfully are the following:

Phosphorus and antimony.

Chromium and antimony.
Arsenic and antimony.

Boron and antimony.

These are in the order of their negative character, phosphorus and antimony being the most negative. Antimony itself is less negative than any of these alloys. The alloys are made in the proportions of the atomic weights of the substances.

All these arrangements are said by M. Kukla to be more powerful than when platinum or carbon is substituted for antimony or its alloys.

In this battery a gutta percha bell cover is used over the antimony, and resting on a flat ring floating on the top of the zinc solution, this effectually prevents any smell, and keeps the peroxide of nitrogen in contact with the nitric acid solution.

When a battery of twenty-four cells was used, M. Kukla found that in the third and twenty-first cells, pure ammonia in solution was the ultimate result of the action of the battery, but only water in all the others.

This experiment was tried repeatedly, and always with the same result.

A battery was put into action for twenty-four hours; at the end of that time the nitric acid had lost 8ths of an ounce of oxygen and 4th of an ounce of zinc was consumed. Now as one quarter of an ounce of zinc requires only 0·06 of an ounce of oxygen to form oxide of zinc, M. Kukla draws the conclusion that the rest of the oxygen is converted directly into electricity, and this view he says is confirmed by the large amount of electricity given out by the battery in proportion to the zinc consumed in a given time; in the above battery each zinc plate had a surface of 40 square inches.

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The addition of peroxide of manganese does not increase the effect of the battery, but it makes it more lasting; the peroxide of nitrogen formed in the bell cover taking one atom of oxygen from the peroxide of manganese. This is evident from only the oxide of manganese being found in the battery after a time. In the salt solution no other alteration takes place than what is caused by the oxide of zinc remaining in a partly dissolved state in the solution.

For this battery M. Kukla much prefers porous cells, or diaphragms of biscuit ware, as less liable to break, and being more homogeneous in their material than any

other kind.

This battery is very cheap, antimony being only 5d. per lb. wholesale, and the zinc not requiring amalgamation.

The second arrangement tried by M. Kukla was antimony, and amalgamated zinc with only one exciting solution, viz. concentrated sulphuric acid. This battery has great heating power, and the former great magnetizing power; it however rapidly

decreases in power, and is not so practically useful as the double fluid battery, which will last about the same power for fourteen days, when the poles are only occasionally connected as in electric telegraphs; certain peculiarities respecting the ratio of intensity to quantity when a series of cells is used, have been observed, which differ from those remarked in other batteries.

M. Kukla, on directing his attention to the best means of making a small portable battery for physiological purposes, has found very small and flat Cruikshank batteries, excited by weak phosphoric acid (1 of glacial phosphoric acid to 20 of water), to be the best; phosphoric acid being very deliquescent, and forming with the zinc, during the galvanic action, an acid phosphate of zinc. A battery of this description does not decrease in power very materially until it has been three hours in action.

Note on the Advantages arising from the Purification of Coal-Gas, by the
Application of Water in an Instrument called "The Scrubber."
G. Lowe.

By

On Changes observed in Wood from the Submerged Forest at Wawne in Holderness. By T. J. PEARSALL, F.C.S.

While the agricultural drainage was cutting, the remains of a forest was found, principally consisting of gigantic pines. Sections of the timber having been obtained for the Hull Philosophical Society, they were carefully piled away; some days afterwards they were found giving a peculiarly penetrating and ætherial odour, showing that some great changes were taking place; after they were separated from each other, it was found that some of these timbers had crystals of a waxy appearance and inflammable character attached to the wood.

On Crystals from the Sea-coast of Africa. By T. J. PEARSALL, F.C.S. The crystals here shown were obtained by Capt. Mitchell of the Merchant Ship 'Frankfield,' while searching the coast of Africa between Saldanah Bay and the island of Ichaboe for guano deposits.

The crystals are of carbonate of lime, enclosing sand; 15 to 20 per cent. sand are obtained from some specimens.

The crystals are very hard and have sharp cutting edges, so as to make it a painful task to walk upon them. The beach was covered with crystals to the extent of miles; about three miles was walked over, but it seemed as far as the eye could reach, and was half to one mile in breadth. Some of the specimens are from 4 to 5 inches in length, showing a thickness of half an inch, and from 2 to 3 inches across the plane; the report given was that some of the crystals protruded up from the sand so far as to wound the ankles and legs without great care in walking over. Some crystals seem to be opake, with the sand enclosed, except at the edges; 15 to 20 per cent. of sand is obtained from portions of crystals; carbonates of lime and magnesia with small quantities of saline matter. Common salt principally can be obtained by breaking them up in distilled water. They are extremely soluble in diluted nitric acid.

Mineralogists and chemists are perfectly well aware of the stony substance called 'Fontainbleu Sandstone,' where the sandstone is found having forms of crystals of carbonate of lime; these crystals now exhibited show the fact of sand of the beach enclosed without altering the general form, and also that the crystal has at its base adapted itself to the sand and other crystals.

These specimens show the great facility on that coast of producing mineralized crystals, and also suggests the opportunities constantly offered to intelligent merchant seamen, of bringing home specimens of great interest which are uncommon in most parts of the world, except in some places, where they may visit, and where there may be abundance.

On Lime Flowers, or peculiarly formed Substances from the brickwork of one of the Reservoirs of the Hull Water-works before final completion for use. By T. J. PEARSALL, F.C.S.

These strange productions were found on one side of a reservoir, neither at the

end nor on the other sides; the brickwork with the mortar and cement had not properly set, and when the first quantity of water let into the reservoir was withdrawn, these substances were found upright on the brick slope; they consisted of irregular tubes terminated by a sort of expansion or bulb. They stood erect in many cases, from the joints of the brickwork having strange shapes; but some closely resembled tulips, the tube having a sort of bulb about the size of a small egg; some of the tubes were found prostrate, that showed they had attained the altitude of 14 to 18 inches. They were all of a gray-white colour, of a rough exterior; inside the tubes and bulbs they were much whiter, and the substance appeared in concentric layers; they were formed, it was supposed, from the soft mortar, by the pressure of the water and filtration of fluids and air through the side, as on that part of the reservoir the whole excavated earth had been thrown up more than 20 feet above the surface of the water in the reservoir.

These substances at their base showed the tubular portions attached to the brickwork, the mortar, and the cement; they dissolved readily with effervescence in diluted nitric acid.

These substances were not observed until the water had been withdrawn, they were then found in parallel lines to an extent of 150 to 200 feet, and so numerous that a small cart might have been filled with these brittle exudations. However much the pressure of water and the passage of air and gases might have in some way contributed to these forms, one learned naturalist had considered it probable that some species of Flustra might have lent its assistance to some of the shapes. Mr. Pearsall stated he had not heard of similar formations.

On the Employment of Pentasulphate of Calcium as a Means of preventing and destroying the Oïdium Tuckeri, or Grape Disease. By ASTLEY PASTON PRICE, Ph.D, F.C.S.

Of those substances which have been employed to arrest the devastating effects of this disease, none appear to have been so pre-eminently successful as sulphur, whether employed as powdered or flowers of sulphur, or by sublimation in houses so affected. But notwithstanding the several methods described for its application to the vines, I am not aware that any has, or had, appeared prior to 1851, when these experiments were instituted, by which sulphur might be uniformly distributed over, and become to a certain extent firmly attached to the vines.

Three houses, situated at Margate in Kent, in the vicinity of the one in which the disease first made its appearance in England, having been for five consecutive years infected with the disease, and notwithstanding the employment of sulphur as flowers of sulphur, no abatement in its ravages could be detected, I was induced to employ a solution of pentasulphide of calcium, a diluted solution of which, having been found to act in no way injuriously to the young and delicate shoots of several plants, was applied to the vines; the object in view being that the pentasulphide should be decomposed by carbonic acid, and that 4 atoms of sulphur, together with the carbonate of lime formed, should be deposited in a uniform and durable covering on the stems and branches of the vines affected. Although but few applications were made, the stems became coated with a protective deposit of sulphur, and the disease gradually but effectively disappeared, insomuch that the houses have been, and now are, entirely free from any disease or symptoms of infection.

The young shoots are in no way affected by its application, and the older wood covered with the deposited sulphur continues exceedingly healthy.

The specimens exhibited to illustrate the durability and protective influence of the deposited sulphur were from vines which in the autumn of 1851 were covered with the disease, but which since the autumn of 1852 have received no further treatment.

The vines in the immediate neighbourhood, and adjoining one of the houses, are covered with the disease, but, notwithstanding their close proximity, no indication of the disease has at present been detected in either of the three houses.

A solution of pentasulphide of calcium is prepared by boiling 30 parts by weight of caustic lime with 80 parts by weight of flowers of sulphur, suspended in a sufficient quantity of water; heat is applied until the solution has acquired a dark red colour, and the excess of sulphur ceases to dissolve. The clear solution is drawn off, and after

dilution with water may be applied to the vines by means of either a sponge, brush or syringe. A saturated solution of pentasulphide of calcium may be diluted with from 12 to 20 times its volume of water previous to being employed.

On a New Method for determining the Commercial Value of Oxide of Manganese. By ASTLEY PASTON PRICE, Ph.D., F.C.S.

It is well known that several methods have been described for determining the commercial value of oxide of manganese, that is to say, for estimating the amount of available chlorine capable of being obtained from a given sample of manganese.

There are, however, certain practical inconveniences attendant on the employment of many of these processes, most of them demanding an amount of time and manipulation which it is most desirable to obviate.

The method I have for some time employed, and which I have found to give accurate results, is based on the conversion of arsenious into arsenic acid by means of chlorine, and the transformation of arsenious into arsenic acid by the employment of a solution of hypermanganate of potash.

The specimen of manganese under examination is dissolved in a normal hydrochloric acid solution of arsenious acid; and the arsenious acid remaining unchanged into arsenic acid is determined by a standard solution of hypermanganate of potash. In employing a solvent containing a reducing agent, it will be found that the solution of the oxides of manganese is materially facilitated, and may be effected at a low temperature in a very short space of time.

In adopting this method, some difficulties presented themselves :

On dissolving arsenious acid in hydrochloric acid, terchloride of arsenic is given off, and it becomes difficult to obtain a correct normal solution. This difficulty is avoided by dissolving the arsenious acid in a solution of caustic potash, and then adding the alkaline solution to an excess of hydrochloric acid.

Another difficulty occurred in effecting the solution of the oxide of manganese in the arsenical solution, as in proportion to the elevation of temperature does the loss of terchloride of arsenic increase. This source of error is prevented by employing a dilute acid solution of arsenious acid, and adapting one of Will's nitrogen bulbs, containing a solution of potash, to the flask in which the oxide of manganese is dissolved. Any terchloride of arsenic which may pass over is there effectually retained, provided solution be effected at a low temperature. The normal solution of arsenious acid is made by dissolving 113.53 grs. of arsenious acid, corresponding to 100 grs. of peroxide of manganese, in a solution of potash, and then adding hydrochloric acid until the solution occupies 100 measures.

A standard solution of hypermanganate of potash is obtained by diluting, for example, 5 measures of the normal solution of arsenious acid, corresponding to 5 grs. of peroxide of manganese, and then determining the number of measures of the solution of hypermanganate of potash that are required to transform the arsenious acid therein contained into arsenic acid.

These two solutions being obtained, an estimation of the value of a specimen of oxide of manganese may be expeditiously and accurately made.

Ten, or any number of grains of the specimen under examination, are placed in a small flask, to which 10 or more measures of the normal arsenical solution are added, and to the flask is adapted one of Will's nitrogen apparatus, containing a solution of potash. The flask is then placed in a water-bath, or a gentle heat is applied until solution is effected. The contents of the flask, after having been allowed to cool, are, together with the solution of potash, transferred to a larger flask, and diluted with water. The amount of arsenious acid remaining unchanged is then determined by the addition of the standard solution of hypermanganate of potash, and the quantity thus indicated being deducted from the number of grains of arsenious acid employed in the first instance, will give the value of the specimen submitted to analysis.

In order to obtain correct results by this method, it is of course necessary that the hydrochloric acid and the potash employed should be free from sulphurous or nitric acid, or any other reducing or oxidizing impurities.

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