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of soap or soda, and the wool is rendered at least equally white, clean, and soft as by other methods. Soluble glass may also be employed advantageously for domestic washing. A bath must be prepared over night, with 20 to 30 parts of water at 50° to 57° C., and of 1 part of neutral soluble glass; the linen is plunged into this bath and left there till the following morning, when, after the bath has been re-heated with additional hot water, it is to be worked with a wooden stamper. The aspect of the solution tells when the linen is nearly cleaned, when the former is to be drawn off and the linen drained. The operation is then completed by rinsing with a little soap; but it is well to pass the linen again through a weak solution, consisting of 1 part of soluble glass to 50 parts of water at 45° to 50° C., and then to rinse it out in pure

water.

CHEMICAL NOTICES FROM FOREIGN SOURCES.

Under this heading will be found an encyclopædic list of chemical papers published abroad during the past week, with abstracts of all susceptible of advantageous abridgment. The two half-yearly volumes of the CHEMICAL NEWS, with their copious indices, will, therefore, be equivalent to an English edition of the "Jahresberichte."

From this spot outwards the distinctness of perception rapidly decreases, and we naturally tend to equilibrate the sensations at the periphery of the object. If one of the horns of the lunar crescent is brought into the field of the fovea centralis, the irradiation there disappears; but by a peculiar compensation that at the other horn appears more than doubled. M. Le Roux further discusses the case of observation with the naked eye (as well as with telescopes when observing transits of Venus) of a dark ligament between two opaque bodies on an illuminated ground, and says that by sustained attention irradiation, but of imperfect accommodation. he can make these disappear. The ligament is not a phenomenon of

Mutual Determination of the Constant of Attraction, and of the Mean Density of the Earth.-A. Cornu and J. Baille.-(See page 211.)

Les Mondes, April 10, 1873.

New Variety of Hexylene.-M. Tchaikowsky.-Among the hexylenes of different origin one is known-that of Buff-which furnishes a primary hexylic chloride on combining with hydrochloric acid. Another-that of Erlenmeyer and Wanklyn-is converted into a secondary hexylic iodide on uniting it to hydriodic acid. It became interesting to attempt the preparation of an isomeric hexylene having the property of transforming itself into a tertiary hexylic iodide on the addition of hydriodic acid. Tchaikowsky has attained this object, setting out from methyl-diethyl-carbinol. This alcohol was obtained by the method of Boutlerow, by causing chloride of acetyl to react upon zinc-ethyl. The alcohol has been converted into the corresponding iodide by the action of gaseous hydriodic acid. On treating this 10dide with an alcoholic solution of potash in sealed tubes, first in the cold lighter than water, having a strong odour, and boiling between 68° and and afterwards at 100°, he obtained a liquid hydrocarbon, colourless, 72°. On analysis it gave 85.06 carbon and 14:57 hydrogen. On combination with hydriodic acid this hydrocarbon yielded a tertiary iodide, that of methyl-diethyl-carbinol, and was convertible into the latter by treatment with moist oxide of silver. On Ethyl-Trimethyl-Formene. W. Goriainow. -This new

Theory of the Sun Spots.-P. Secchi.-This is a reply to M. Faye's last note correcting certain misrepresentations. In an appended note the writer states that, having examined the drawings of sun-spots and protuberances in 1871 and 1872, he finds that of 300 spot groups in the former year 209 were accompanied with eruptions (or two-thirds); of 292 in the latter 150 (or about a half): a proportion which he thinks significant for his theory.

Reply to P. Secchi and to M. Vicaire.-M. Faye.-The writer vindicates his former assertion that the eruption hypothesis involves a number of gratuitous assumptions.

Report on a Memoir of M. Boussinesq Entitled "Essay on the Theory of Water Currents."-The committee give a somewhat lengthy analysis of this important work; in which M. Boussinesq treats of the motion of water in pipes and in open channels-considering fluid sections of various forms, especially those which are rectangular and of considerable breadth, constant, or gradually variable, and the circular or semicircular. Also cases in which the bottom of the channel presents longitudinally a sensible curvaturenon-permanent movements, such as those in rivers at times of floodthe laws which regulate the propagation of waves at the surface of flowing water, with the influence of slopes, friction, curves, &c. The committee remark on the agreement between the author's theoretical results and those of actual experience, and regard the treatise as one of much practical value.

New Observations on the Theory of Solar Cyclones.-M.

Vicaire.

Note on the Effects Produced by Currents on Mercury Immersed in Different Solutions.-Th. du Moncel.-When the current from a battery of 8 Chutaux elements is passed through springwater for an electrolyte-the electrode being a large drop of mercury connected with the negative pole, and a platinum wire with the positive-the polarisation current, on closing the secondary circuit after five minutes action of the battery, and through a circuit of 12 kilometres of telegraph wire, has at first an intensity represented by 7 or 8 degrees on a zinc galvanometer with two spirals of wire. This current gradually disappears in three minutes. With acidulated water the effects were less. With a saturated solution of chloride of sodium (other conditions the same) the polarisation current had at first an intensity of 25°, disappearing in fifteen minutes. With potash solution (salt in proportion of a fourth of weight of water) primary strength 26°; disappeared in fourteen minutes. With 3 per cent solution of cyanide of potassium, 18° 45'; twelve minutes. With solution of chlorhydrate of ammonia, 45° to 50°; five minutes. Thus we may form with these solutions gas couples and batteries of polarisation more energetic than those which have for base oxygen and hydrogen.

On

process which Lwow used for the preparation of tetramethyl-formene. Each drop of zinc-ethyl added to the tertiary iodide of butyl produces a strong reaction and rise of temperature. The fumes were passed first into hydrochloric acid, and then into alcohol well cooled. adding water to the alcoholic solution and distilling, the hydrocarbon is collected as a colourless liquid. After treatment with bromine, and removal of the excess of the bromine by means of alcohol, the hydrocarbon is rectified, and treated for some time in the water-bath with metallic sodium. The greatest part of the purified hydrocarbon passes over at 43° to 48°. It contains 83 65 per cent of carbon, and 16.84 per cent of hydrogen. Its formula is assumed to beCH, CH1(CH),

Formation of Tertiary Chloride of Butyl by Means of Isobutylen.-D. Salewsky.-Isobutylen was condensed in tubes containing concentrated hydrochloric acid, and well cooled. The tubes were then sealed and heated for some hours in the water-bath. On opening the tubes there was no escape of gas or vapour; all the isobutylen was combined, with formation of tertiary butylic chloride, almost pure.

Transformation of Amylene into Amylic Alcohol by Means of Sulphuric Acid.-M. Flavitzky.-A mixture of 2 parts of concentrated sulphuric acid, and I part of water was employed. The amylene was caused to act upon it in the state of vapour.

Action of Bromised Bromide of Acetyl on Zinc-Methyl.D. Idanow. The results obtained are indecisive.

Trimethyl-Acetic Acid, a New Isomer of Valeric Acid.A. Boutlerow.-The acid is volatile without decomposition at 160.5° to The 1615°. The distillate is colourless, and solidifies immediately. Its odour recalls composition is C,H10O2. It is insoluble in water. that of acetic acid and valeric acid, but is less offensive than the latter.

Le Moniteur Scientifique Quesneville, April, 1873. New Method of Oxidation, and New Explosive.-MM. Houzeau and Renard.-Hitherto chemists have only employed complicated reagents to disengage oxygen at higher or lower temperatures, such as mixtures of concentrated sulphuric acid with peroxide of manganese and bichromate of potassa, or bodies rich in oxygen like the chromic and nitric acid. These oxidising agents are open to the grave defect of determining either secondary reactions due more frequently to the influence of the acids or bases employed than to the oxygen liberated; or of producing too violent action which, raising the temperature, renders it impossible to trace the formation of the primary products. Houzeau has conceived the idea of employing concentrated ozone as an oxidising agent. He had previously shown the method of obtaining ozone in a concentrated state, by means of a simple tube supplied within and without with a metallic armature. As the decolourising power of ozone in relation to indigo is 40 times greater than that of chlorine, Houzeau was led to apply it to the formation of new organic compounds. One of the most remarkable results is ozobenzine, formed at ordinary temperatures by the action of concentrated ozone upon benzol. Ozo-benzine is a white, amorphous solid, which is immediately decomposed with violence when its temperature is sensibly raised. Its explosive force is so great that if a few decigrms. are submitted to a slight shock the windows of the room where the ex

detonates immediately with violence if brought in contact with concentrated ozone. If we take in connection with these facts the former observations of the same author on the presence of ozone in the air, and on the natural circumstances which seem to concentrate it occasionally in certain points of the atmosphere, we are entitled to ask whether, in some cases, conflagrations and explosions may not be due to this powerful chemical action, without any negligence or criminal intention on the part of persons concerned?

La Revue Scientifique de la France et de l'Etranger,
April 19, 1873.

This number contains no original papers on chemistry or its allied sciences.

PATENTS.

ABRIDGMENTS OF PROVISIONAL AND COMPLETE SPECIFICATIONS

DELIVERED FROM OCTOBER 5 TO OCTOBER 11, 1872.

A new or improved process for the manufacture of soap. William Lorberg, North Bow, Middlesex. October 8, 1872.-No. 2959. The features of novelty of this invention consist in a new or improved process of manufacturing soap. I take a definite quantity of fat, animal or vegetable, or a mixture of the two, or a mixture of either of the two and rosin in the state of thick oil in proportions varying according to the quality of soap it is intended to produce, the finer varieties of fat yielding a soap superior to that formed by lower descriptions of fatty matters. The fats to which I particularly refer are tallow, mutton suet, or a mixture of the two known in the trade as "melted stuff." Animal oils, such as fish oils, cocoa-nut oil, palm oil, palm-kernel oil, cotton-seed oil, olive oil, and the like. The said mixture is heated to the melting-point, say about 100° F., the object being to have the fats in a liquid state at as low a temperature as possible, merely to insure contact with the chemical ingredients, afterwards to be mixed with them. To this mixture I then add gradually and with diligent stirring from 50 to 60 per cent of a solution of caustic soda, indicating in the cold from 30° to 40° Baumé. As soon as combination has taken place, which it does with evolution of heat in a few minutes, I add water, solution of glutin, silicate of soda, or silicate of soda and potash, and for certain kinds of soap sulphate of soda, alumina, and carbonate of potash. The proportions of all these matters vary with the proposed quality of the soap, but in general' they are as follows, namely, fat 100 parts, alkali 50 to 60 parts, silicate of soda or of soda and potash 25 to 50 parts, glutin 25 to 50 parts, water 20 to 50 parts. All the ingredients are added to the above compound in the cold, and thoroughly incorporated by stirring. The mass, which is now of a creamy subsistence, is covered up, allowed to heat and cool down again, which requires from twenty-four to forty-eight hours more or less, after which it is ready to be taken out of the frames and cut into slabs or bars, as may be desired. The soap then only requires to be seasoned, that is to say, to be exposed for some time to the influence of the atmosphere In a drying-room or other convenient shelter, which hardens and dries it. Improvements in the manufacture of artificial manures. Benjamin Tanner, Liverpool, Lancaster. October 9, 1872.-No. 2974. This invention consists in the economical production of single, double, and triple superphosphates having one, two, or three alkaline bases instead of the lime, or in addition thereto, and the production of ammoniacal matters in combination or admixture therewith in a more or less rapidly soluble condition, so as to produce highly concentrated artificial manures. For the convenience of description the following paragraphs, which describe the processes embraced by this invention, are numbered consecutively:

1. Solutions of any form of phosphate of lime and other mineral phosphates are made in hydrochloric acid, phosphoric acid, water, or mixtures thereof, by well-known arrangements. These solutions are treated with silicic acid, or sulphuric acid, or oxalic acid, or mixtures thereof, to remove any portion of the lime present, and, by preference, to reduce it in relation to the phosphoric acid to the proportion present in mono-calcic, bi-calcic, or tri-calcic phosphate. Sulphate, silicate, or oxalate of potash or mixture thereof, is or are then added to the liquor, for the purpose of removing all or a portion of the lime, and for substituting potash. The liquor is separated from any insoluble salts formed, and the clear liquor, on evaporation, yields a superphosphate of potash more or less intermixed with superphosphate of lime, and in such proportions as may be desired. Any other corresponding alkaline salt or salts may be used instead of, or in conjunction with, the potash added thereto, and any form of single, double, or triple superphosphate can thus be produced.

2. A very similar result is attained by adding the base or bases to be substituted for the lime or alkaline matter in a caustic condition, or in combination with any acid or elements which during the process of manufacture are decomposed or volatilised, such as chlorides, for example.

3. Phosphoric acid, or phosphoric and hydrochloric acids, more or less diluted with water, are also treated with the base or bases in a caustic condition, or in combination with any acids or elements (such as chlorides), which during the process are decomposed or volatilised, and their solutions, when evaporated, produce any form of single, double, or triple superphosphate. The superphosphates produced by the processes above described are sometimes further concentrated by dissolving the soluble portion in water, separating the insoluble matter, and evaporating the liquor as hereinafter described. If desired an additional quantity of alkaline matter is added.

4. These solutions, when prepared for evaporation, are intermixed with shoddy, woollen waste, blood, flesh, or other form or forms of nitrogenised matter, and evaporated to dryness, a single, double, or

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triple superphosphate being obtained, having ammoniacal matter in a slowly soluble form intermixed therewith.

5. The solutions described in paragraph No. I are also treated in the manner therein described, or solutions of phosphoric acid are intermixed with shoddy, woollen waste, blood, flesh, or other form or forms of nitrogenised matter, and evaporated to dryness. The product I call " ammonio-phosphate."

6. Phosphoric acid or solutions of phosphate of lime and other phosphates in hydrochloric acid, phosphoric acid, water, or mixtures thereof, is or are intermixed with ammonia, and with sulphate or bisulphate of lime. The proportions of the materials shall be, for every equivalent of phosphoric acid present there shall be present one, two, or three equivalents of lime, or any intermediate quantity; and for every equivalent of sulphuric acid there shall be one equivalent of ammonia present. The insoluble matter may be separated, and the clear liquor evaporated. The product will be a superphosphate of lime having ammonia in a rapidly soluble form intermixed therewith. 7. When it is desired to separate any portion of the ammoniacal salt formed as described in paragraph No. 6, the liquor which has been prepared for evaporation is concentrated sufficiently to enable the ammoniacal salt to crystallise out, the remaining liquor is evaporated to dryness, yielding a product similar to that described in paragraph No. 6, but less rich in ammonia.

8. The several forms of superphosphate herein described may be phosphated and rendered more powerful as a manure by the addition of phosphoric acid thereto.

9. It is preferred to carry out the evaporation by the use of steam, or hot air, or mixtures thereof, the action being safer and more satisfactory.

Improvements in the manufacture of alkalies, and in apparatus employed therein. James Hargreaves, chemist, and Thomas Robinson, ironfounder, Widnes, Lancaster. October 10, 1872.-No. 2982. Our said improvements consist, first, in intimately mixing sulphate of soda and sulphate of potash, or either of them, with coal or other carbonaceous material and metallic oxides, and fusing them in a crucible heated from the outside, the said crucible having an outlet at the bottom to allow the fused crude soda or potash to flow out when finished. Second, in using iron, preferably cast-iron, to form the crucibles aforesaid, or to form the beds and sides of furnaces used in the manufacture of crude soda or potash.

Improvements in evaporating liquids, and in the means or apparatus to be employed therein. Albert Ungerer, chemist, Simmering, near Vienna, Austria. October 10, 1872.-No. 2985. This invention, which relates to improvements in evaporating liquids, consists of a perpendicular shaft or tower constructed of stone or other suitable material, and covered with a perforated platform or cistern, from which a considerable number of wire or other ropes or rods are suspended into the interior of the tower. The liquid to be evaporated is first conducted to the top of the tower, and then allowed to run down through the perforations in the cover along the ropes or rods at a speed which can be regulated according to circumstances. Hot air or the products of combustion proceeding from a furnace enter the tower near its base, and escape through an opening near its top, meeting on their way the liquid spread over the immense surface afforded by the ropes, and thus concentrating the same by evaporation, more or less according to the heat of the gases and the speed at which the liquid is allowed to run down the ropes. It is preferred to place a cistern at the base of the tower, in order to collect the concentrated liquid and so that it may be removed.

NOTES AND QUERIES.

Action of Heat on Gems.-The effect of the oxy-hydrogen flame upon beryls and emeralds has been fully studied by Mr. Greville Williams, whose results will be published very shortly.

Oxychloride of Lead.-Can any of your readers inform me if it is possible to make oxychloride of lead perfectly white, and how?-C. Removing Smell from Dissolved Gutta-Percha.-Would any of your readers kindly inform me of a method of removing the disagreeable smell left in gutta-percha and other substances when bisulphide of carbon has been used as a solvent? Long exposure of the substance, even in thin films, to the air does not answer the purpose. -M.

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THE

SUPPLEMENT

ΤΟ

VOL. XXVII. No. 701.

ON THE

ALKALINITY OR ACIDITY OF CERTAIN SALTS AND MINERALS, AS INDICATED BY THEIR REACTION WITH TEST-PAPER.*

By W. SKEY, Analyst to the Geological Survey of New Zealand. A KNOWLEDGE of the reaction of various substances with test-paper is justly esteemed of considerable importance, since it enables us at once to refer them to one or other of three distinctive groups, each of which has strict regard to the molecular structure of those substances falling within it, as manifested by the chemical combinations they are most prone to form. These groups are, as is well known, the alkaline or basic, the acidic, and the neutral, and properly prepared testpaper indicates the one to which any particular substance belongs, by suffering certain colourations when brought in contact with it, these changes being the result of chemical ones, by which the combinations previously existing among the colouring matter of such paper are ruptured, and new ones superinduced.

The terms alkalinity and acidity, therefore, have a signification expressive of condition, and their real meaning is only this, that, as applied to any substance, they indicate a tendency in such to form combinations with acid or alkaline bodies, as the case may be. Neutrality, however, has a relation more to the breaking-point (if I may so term it) of these combinations in the litmus-paper, than to absolute condition of the substance tested; for it is easy to conceive that a substance may be acid or alkaline, and still, by reason of the feebleness of either of these characters, be unable to overturn the combinations referred to, and so manifest either of these reactions.

I only point this out that I may not be misunderstood in the use I make of the term neutrality, and not for the sake of opening a question, as I do not attempt here to remove the neutral point thus arbitrarily located to a position nearer to the true one, preferring to take up ground less subject to criticism, and of more immediate interest, viz., that set forth in the heading of this paper, to which, after the above necessary explanations, I now address myself.

These reactions being in general so easy to obtain in the case of bodies capable of manifesting them, I may perhaps be deemed hypercritical when, in the course of this statement, it is found that my remarks tend to show that the condition of certain of these bodies, as demonstrated by such tests, has been misstated in our popular works on chemistry, and that this has tended inferentially to involve us in further errors relative to the numerous substances chemically allied thereto; at the risk of being thought so, however, I do not hesitate to make the following remarks, and the exact condition of such bodies shall be the principal subject of this paper.

The ores I particularly object to as having their true characters in these respects misstated, or inferentially liable to be misapprehended, belong to a class of salts insoluble, or nearly so, in water. They are the carbonates, borates, silicates, phosphates, and arseniates of the alkaline earths (lime, baryta, strontia), also of magnesia, silver, and lead. Theoretically, they should be alkaline, from the following considerations.

Taking an equivalent of any of these bases, and combining it with one of sulphuric or any of the stronger acids, we have a salt corresponding to those of the alka

Read before the Wellington Philosophical Society.

common character in respect to this particular reaction.

Now the alkaline carbonates, borates, and their common phosphates, &c., give a very decided alkaline reaction with litmus-paper, properly prepared; they are indisputably alkaline, but the corresponding salts of lime, strontia, &c., are, as a rule, accepted either from experimental results direct, or from inferences based on them, as being neutral, although, from the above considerations, they ought to be alkaline.

The importance of ascertaining which of these two assumptions is correct is obvious, for, if these salts are in reality neutral, we learn, and must take cognisance of, a radical difference existing either in the acids or the bases of which these salts are made up, according as the other portion of the salt is possessed of powerful or weak affinities. In such a case lime, for instance, would not retain the same degree of saturating power (quantivalence) through all its combinations with the acids, the degree of this in any case being determined by the strength of the acid employed; a strong one being thus necessary, as it were, to draw out its highest capabilities in this respect.

Our recently acquired knowledge of the mobility (if I may term it so) of the component molecules of bodies in respect to each other, even in the case of simple elements, and the great tendency many of them manifest to form intercombinations among themselves, dispose us favourably towards a belief which, by ascribing a variable potentiality of this nature to these bodies, explains away the apparent anomaly I have just referred to as pertaining to them in their present reputed condition, and make it very desirable to have experimental results, by which to enable us to decide between theory and our present belief. Results, therefore, having for their sole purpose this object I now relate, from which it will be seen, I think, that theory is in this case our safer guide.

The ground taken up by these results has been already just broken in upon, as will perhaps be remembered, in a communication to this Society, entitled "The Alkalinity of Carbonate of Lime," and while the criticism which it evoked has been already useful in stimulating me to this inquiry, it will be useful again, but in a different manner, by supplying us with a knowledge of the precise conditions deemed necessary, by a well-known chemist, to insure reliable indications when testing substances generally in respect to their behaviour with the test I am employing-litmus-paper. Using the precautions recommended in this criticism, I prepared the test (litmus-paper) for use by simply washing it in water free from ammonia till it acquired a pale violet colour, in which condition "it is a delicate test for either acids or alkalies."

Thus prepared, the test, when pressed upon them in a moist state, indicated the conditions of the following substances to be as stated below:

If the terms acidity and alkalinity have any meaning, or if the test here applied to discover these properties is trustworthy, we cannot refrain from classifying those substances specified in the first and second columns of the foregoing table as alkaline and acidic respectively. That the test used is trustworthy, in the case of alkalinity at least, and these results consequently so far correct, is in the highest degree probable, from the fact that it has been approved of, and I may say recommended, for this latter object, by one who attempts to demonstrate the condition of neutrality in a case for which, as aforesaid, I have assigned alkalinity.

The correctness of this table being allowed, we may safely and largely add to it by filling in with those salts analogous in chemical composition to the ones stated, or we may at once deduce from it the following general conclusions:

(1). That those salts of the earthy oxides, as also those of the oxides of silver and lead, which contain single equivalents of carbonic, phosphoric, arsenic, or boracic acids, are alkaline.

(2). That the common silicates of these oxides are also alkaline.

(3). That the salts of the sesquioxides and the remaining metallic protoxides are acid when containing one equivalent or more of phosphoric or arsenic acid.

(4). That the silicates of the sesquioxides are neutral. The salts of the oxides, therefore, enumerated under the foregoing Nos. 1 and 2 appear to agree, in respect to the characters under investigation, with the corresponding salts of the alkalies; the oxides themselves, as compared to those of the so-called alkalies, thus exhibiting an equal alkalinity through all their combinations, and therefore each oxide is, as far as we can judge, similar in molecular arrangement throughout all such combinations.

In the case of those salts comprised in section 3, it is seen that they compare with the sulphates and chlorides of the same or corresponding bases in being acid; but the degree of this acidity is, we know, dissimilar, and may be inferred from the character of alkaline salts with these acids respectively, which has been already described.

The facts above stated have a great significance in respect to the relative potency of the alkalies as compared with that of the alkaline earths; thus, the perfect equality of the bases magnesia and lime as compared with potash (equivalent for equivalent) in respect to alkalinity (here shown) will, if fully recognised, oblige us to dispute the title which this base now holds-that of being the most powerful of any we are yet conversant with.

In reality, lithia has far better claims upon this position, as having the lowest combining number, and being, equivalent for equivalent, undoubtedly equal to potash in basicity, it has, therefore, for similar weights, the greatest saturating power for acids.

Next to lithia is magnesia, then lime, soda, and afterwards potash. In this connection it is proper to remark that lithia is the only base which readily attacks platinum when fused upon it-a pretty good test of strength, one would think, and proving, as far as a single result has weight, that the relative position I here assign to this base is correct.

Both potash and soda, however, have certainly an appearance of being far more powerfully alkaline than any of the bases just compared with them; but this is due simply to the fact that they dissolve in water to a larger extent, and with far greater speed than these bases, whereby they are enabled to act with greater facility, and effect more, in a given time.

The fact is that, in our use of the term alkalinity, hitherto we have not expressed absolute potentiality, but rather energy or speed of action, and this speed being dependent (other circumstances being equal) upon the degree of solubility in water of the substance tested, we have thus unconsciously perverted the true meaning of the term (alkalinity), by making it denote a certain degree of

solubility-a quality which we do not know is the least related to it.

It only remains to notice that, in relation to rocks, the terms basicity and acidity have, by the facts above stated, their significance enlarged, and their appropriateness rendered still more apparent than before, while the term neutrality is now shown to be predicable of certain of them, and to be equally significant.

The character of rock masses, or portions of them, in these respects may be discovered in a very direct and simple manner, by just pounding a portion of them upon litmus-paper moistened and properly prepared, when, according to the results and manner of sampling, we know off-hand the true condition of the specimen as a whole, or of any particular portion of it; and, knowing this, we learn at once the general affinities of such rocks or portions of rocks, or to particularise whether they are absorbent of acid silicates or silica, or of basic silicates (as the earthy or alkaline ones), or whether, as in the case of clay or clay slate, they are negative to both these

classes of bodies.

I may add, in conclusion, that the rationale of the new process for the retention of the fertilising constituents of sewage by means of phosphate of alumina is readily explicable by the fact that this is an acid salt (see table); it is thus enabled to chemically absorb all the more basic organic portions of such sewage, these being generally the most valuable for manure, as they are, I believe, the inost noxious to animal life.

PROCEEDINGS OF SOCIETIES.

MANCHESTER LITERARY AND PHILOSOPHICAL

SOCIETY.

Ordinary Meeting, April 15th, 1873.

R. ANGUS SMITH, Ph.D., F.R.S., Vice-President, in the Chair.

MR. WILLIAM THOMPSON was elected an Ordinary Member of the Society.

The following letter from Mr. WILLIAM BOYD Dawkins, F.R.S., was read:

As Secretary of the Committee of the British Association for carrying on the exploration of the Victoria Cave, I am obliged to notice the "Notes on Victoria Cave," by Mr. W. Brockbank, published in the Proceedings, March 10th, 1873, pp. 95 et seq. The notes in question are based partly on Mr. Brockbank's examination of the cave during two visits, with an interval of two years between them, partly on the facts recorded by Mr. Tiddeman and myself, and partly on a ground plan constructed by our superintendent, Mr. Jackson, for the Exploration Committee, that is not yet published. I submit that, until the work of the Committee to which the cave has been handed over by the kindness of the owner be finished, and the observations, to which Mr. Brockbank has had no access, be recorded, his notes must of necessity be imperfect and liable to error. How much he is in error as to matters of fact may be estimated by the examination of the statement, p. 97-" the day before my visit a mass of at least 100 tons had fallen from above the face of the Victoria Cave." Mr. Jackson writes me that not even a mass weighing 1 ton, although two blocks possibly of 10 cwts. each, had fallen. The statement at p. 96, in which I am made to differ with Mr. Tiddeman as to the presence of the pleistocene mammalia inside the cave, is altogether unfounded, and the inference that I "varied my description" after my paper came before the Society is negatived by the fact that the abstract in question was printed for private circulation in 1872. The remains occur at the entrance and extend both inside and outside the cave, as

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I pointed out in my diagram. These are merely two out of many points which have been raised, and which do not lead me to alter my conviction that the stratum containing the mammalia is of pre-glacial age, or to undertake any responsibility as to the views which I have not advanced. Were I to discuss all the points which have been raised, I should anticipate the Report of the Committee to the British Association. If these hasty and necessarily imperfect observations were not calculated to throw discredit on the Exploration, I should not trouble the Society with this note.

On some Improvements in Electro-Magnetic Induction Machines," by HENRY WILDE, Esq. An abstract of this paper will appear in an early number of the CHEMICAL NEWS.

MICROSCOPICAL AND NATURAL HISTORY SECTION. Extraordinary Meeting, December 11th, 1872. JOSEPH SIDEBOTHAM, F.R.A.S., in the Chair. MR. JAMES M. SPENCE exhibited a large and interesting collection of natural history and other objects from Venezuela. Mr. Spence had lately returned from that country, in which he spent eighteen months, during which time he accumulated a very extensive collection.

The natural history collection contained a number of hunter's skins of the larger animals of prey and of the chase; but the great wealth and beauty of the fauna of the country was best illustrated by the extensive collection of birds, which is probably the best ever got together, and embraces examples of nearly all the tribes found in the Venezuelan Republic.

The economical portion of the collection was of great interest and value, chiefly from its extent and the care which had been exercised in its collection and transportation, and the valuable notes of Dr. Ernst of Caracas, which accompany it, rendered it still more valuable. Specimens of the vegetable and mineral productions of Venezuela were to be seen in great number and variety. Among the plants exhibited was a small collection of Characea named by Dr. Ernst, but the chief interest was in a small collection of plants gathered by Mr. Spence on the summit of Mount Naiguati.

This mountain, whose altitude is nearly 9,500 feet, is the highest in Venezuela, and was regarded as almost inaccessible until Mr. Spence and five companions made a successful ascent in April, 1872. A species of grass allied to the bamboos, and new to science, was one of the results of this ascent.

The exhibition also included an assortment of interesting curiosities of native manufacture, recent and ancient. There were goblets, drinking cups, and flasks more or less finely carved out of cocoa-nuts, some mounted in silver; and a series of delicately-worked cups and bowls of calabash.

From the State of Trugillo, Mr. Spence has brought three curiously-shaped vessels obtained from Peruvian burial places.

The collection remained open to the public for some days, and was visited by a large number of persons.

January 27th, 1873.

The collection contains gold in quartz of very rich character, argentiferous ores, green and blue carbonates of copper, copper pyrites, galena, iron ores of various kinds, carbonaceous minerals, calcites, silicas, and rock specimens of gneiss, mica, taic schists, kaolin, hornblendic rocks, and serpentine, with a few imperfect fossil and silicified woods.

The gold quartz of the richest kind came from the province of Guayana, where vast regions of auriferous rocks occur; and where also gold is found in small grains, flakes, and nuggets of all sizes from an ounce to many pounds weight, in a clay from 2 to 8 inches thick, as well as in a red peroxidated iron earth, both probably alluvial drifts. The quartz veins are richly impregnated with gold in crystals and strings, as may be seen in specimens in the collection. Other specimens of the gold rocks come from the Isle of Aruba, and Loro Estado, Tacasumino.

The argentiferous ores are galenas and cupriferous, and are not of very great richness; they are from La Guaira, Cumanà, and Coro, where decomposed galenas are worked for silver.

The copper ores include twenty specimens from mines that have been worked with profit, one of which, the Aroa mines in the province of Yaracui, is the most famous for the superior richness of its carbonates. The specimen of cuprite from this mine or Quebrada has some long and beautiful crystals of olivenite with cubes of strontian, and from Aragua are specimens of pyrargyrite or red silver ore; others from Caracas, Coro, and the river Tui, include malachites and a native sulphate of copper, probably a crystallisation from the waters issuing from the mines. The chalcopyrites are neither numerous nor very good; the best comes from the Aroa mines, the small granular pyrites appears to be most abundant in a decomposing gneissoze rock.

The galenas are from mines at Los Teques, Aroa, and Campano; several are pseudomorphous crystals in filmy aggregations, interesting specimens for the mineralogist. The iron ores include specimens of pyrites (mundic) which in Venezuela appears to be as abundant as in most palæozoic regions; ten of the samples are rich, and would be profitable if the cost of mining is not too expensive at Barquisimeto, Caracas, and the Aroa mines.

The hæmatites include specular, micaceous, and red iron ores, all comparable to the best European ores. The limnites comprise bog-iron ore of recent formation and a brown amorphous ore. The siderites include an aggregation of tabular crystals from Caracas, probably a carbonate of protoxide of iron valuable in making steel, and massive clay ironstones from the districts of Corui Machate, where coal is also worked. The crystallised and compact magretites come from the same place. A thin vein of brown siliceous ironstone has its surfaces covered with minute fragments of clear quartz, singular and beautiful under the microscope.

The carbonaceous minerals are coals, graphite, sulphur, asphaltum, and petroleum. The coals are from Nuevo Mundo, where Mr. Spence has proved the existence of workable coals, the Island of Toas in the Lake Maraciabo, and a cannel coal from Coro, with several black shales from these localities. These coals are undoubtedly of excellent quality, and from report can be worked economically; their age is at present unknown, from the want of any proper geological survey, and in the absence of fossils of any kind in the shales in this collection; in all probability, however, the Venezuelan coals are of true

The graphite from Caracas is an impure, amorphous, earthy kind, in schists of 2 inches thick, occuring in talcose and micaceous rocks. The sulphurs are massive and of good quality from Campano, Cumanà, and Coro. Asphaltum and its varieties are reported to be found on the coasts in great deposits and in springs: the specimens in the collection are of excellent quality.

The twelve rock specimens of quartz crystals include some of equal purity and size to those obtained from