plants from that which is in an unavailable form, we would go far toward accomplishing what was originally claimed for soil analysis; and this Dr. Peter attempted to do by treatment of the soils with carbonated water. It cannot be doubted, however, that plants, as well as agriculturists, have at their disposal much more powerful, or at lest more energetic, solvents; and that, therefore, a determination of those ingredients which may fairly be considered practically within the reach of agriculture, must go deeper than does that with carbonated

water.

Opinions may differ widely as to the proper strength and nature of the solvent ("Aufschliessungsmittel") to be selected. Hydrofluoric acid, or ignition with the alkaline earths, would evidently go too far; as no soil, probably, will ever yield up the whole of its nutritive ingredients to plants, and fertility is far from being proportional to the whole amount of potash, phosphoric acid, &c., contained therein.

When, however, a partial solvent of uniform strength is used in all cases alike, and its action continued for the same length of time, it may fairly be presumed that, as between soils of similar origin, the amounts so rendered soluble are, in a measure, proportional to the amounts of available nutriment present.

In using hydrochloric acid of the strength III to 1'12 sp. gr., obtained by slow steam distillation of stronger or weaker acid, rejecting the first and last portions, I have in most cases found quite a satisfactory agreement between the results so obtained and the experience of cultivators as to the productiveness and duration of the respective soils; always provided, that the difference in the amounts of inert sand present, of specific gravity, of depth of soil, &c., were taken into account.

The proviso is important, but that with a proper local knowledge these allowances can be made, and that in most cases the information thus gained regarding the nature and treatment of the soil will be vastly more complete and reliable than the judgment of any number of "old intelligent farmers," my experience has fully convinced me; witness the egregious mistakes daily made by such in the selection of new lands. Moreover, a small minority only of farmers is likely to possess the requisite "age and intelligence;" and it is quite important that the multitude of those less fortunate should have the benefit of all the help science can give them.

I will adduce but one" odious example " of a widely prevalent error in reference to the character of a class of soils that I have as yet been unable to eradicate, even from among the "old and intelligent;" who are unfortunately very much given to theorising on inadequate premises. Our prairie soils are notoriously limy; they are also "very sticky;" and the mud takes the hair off the feet of cattle, Ergo, every "sticky" clay soil in the State is called, considered, and treated as a "prairie" soil, especially if the hardened clods adhering above the hoofs of cattle should carry the hair with them. If such soil is unthrifty, and rusts cotton, it is because "there is too much lime in it," which "scalds" the seedlings. In matter of fact, most of these soils are notably deficient in lime, so as to be most directly and immediately benefitted by its application wherever it has been tried, in accordance with my suggestion. The lime here acts probably as much chemically as physically; the clay being rich in potash, as per analysis. While the physical defects of these soils are doubtless the main cause of the crop failures, yet analysis has suggested a remedy which relieves, for the time being, from the necessity of the more costly improvements; lime being comparatively easy of access. Analogous cases are far from infrequent, both in this and in the adjoining States; and I have been led to attach special importance to the determination of lime in soils, from the (not unexpected) rule which seems to hold good very generally, viz., that, cæteris paribus, the thriftiness

See, for example, the article "Heavy Flatwood Soil," in my Miss. Rep., 1860, pp. 276, 279.

of a soil is sensibly dependent upon the amount of lime it contains; while, at the same time, in the usual mode of culture without return to the soil, the duration of fertility is correspondingly diminished, and its cessation is very abrupt wherever much lime is present.

It may be said that, after all, this is but what, from data already known, might have been expected. Granted; then, a fortiori, soil analysis, involving the determination of lime, is of considerable use in determining the present and future value of soils.

In speaking of the "amount" of lime, I must be understood to refer, not so much to its absolute percentage, as to its quantity in comparison with that of potash, which, with phosphoric acid, is what all our fertilisers chiefly aim to supply. Their determination must, of course, be considered of prime importance, since their absence or extreme scarcity is fatal to profitable fertility; while, when they are present, even though immediately available for absorption to a slight extent only, we possess in lime, ammonia, &c., and the fallow, ready and powerful means for correcting their chemical condition.

Here again, the practical value of soil analysis is direct and indisputable. It is of no small interest to know whether the soil we intend to cultivate contains 0'75 per cent of potash and o'25 of phosphoric acid, soluble in HCl, or only the fifth or tenth part of these amounts. One will bear improvement of all kinds-will pay for underdraining, terracing, &c. ; while the other, quite similar in aspect perhaps, would not, according to Liebig's testimony, ordinarily be capable of profitable culture.

Again, it is well known that the same species of plants may occupy soils of widely different quality and value. True, an attentive observer will in such cases see differences in the mode of development; yet these are often such as to escape ordinary remark, and grievous disappointments frequently arise from this source, with new settlers especially. It is of no small importance to be able to identify, as well as to distinguish, soils resembling each other; and this soil analysis can undoubtedly do, if there is any virtue in the law of probabilities even-admitting all that may otherwise be said against their reliability.

Even if no other direct benefits than those already mentioned could be obtained by the chemical and mechanical analysis of soils (which I do not admit, and expect to prove otherwise hereafter); even if we leave out of consideration the addition to our general knowledge which may fairly be expected to result from extensive series of such investigations, carried out upon a uniform plan, whereby accidental errors (whether caused by "birds or squirrels," or analytical and other mistakes) will be eliminated; even thus, I contend that the practical and theoretical value of soil analyses is sufficiently great to justify whatever labour and expenditure may be bestowed upon them by state and national surveys; and that the neglect with which this branch of research has of late been customarily treated, is the more to be regretted as no probable amount of private effort can accomplish what must, of necessity, be done on an extended scale and with the prestige, voluntary assistance, and interest not usually accorded to any but public enterprises. And with due deference to the author of the two volumes whose extraordinary merits no one appreciates more than myself, I call upon my colleagues in State surveys, especially in the West and South, to re-consider this subject before it is too late, and a legislative fiat declares their work to be “finished." It is true that the agricultural colleges must and will take up and continue, as far as possible, the investigation of the agricultural peculiarities of each State; but the special and local experience acquired by those conducting a field survey, as well as their opportunities for extensive and comparative observations, are unfortunately "not transferable," even to the finest quarto report. In order to attain their highest degree of usefulness, our agricultural

* Miss. Rep. 1860, p, 203.

THE CHANGES WHICH COAL UNDERGOES BY EXPOSURE.

By H. ENGELMANN, E.M.

THE subject of loss of carbon, or rather of deterioration, which stone coal suffers by exposure has of late attracted much attention amongst American mining engineers and metallurgists. The different coals are not equally affected by exposure. Their texture, their chemical composition, and the impurities which they contain, exercise consider able influence. Under otherwise equal conditions those stone coals suffer most which contain a large proportion of easily decomposed hydrocarbons, or which have little cohesive strength. Gas coals, after having been stored long, make less and poorer gas than when they are fresh from the mine, and coking coals lose their coking quality, more or less; some kinds are said to deteriorate very markedly within a few days after being mined.

The nature of the changes which take place with the coal, and the conditions which influence them, still form a fruitful field for investigation. A large number of interesting experiments on this subject were made by Dr. Richter, Professor at the Mining School at Waldenburg, in Prussia, which deserve to be far more widely known than they appear to be in this country at least. A detailed account of them may be found in Dingler's Journal, 1870. I will confine myself to stating some of his principal results. As soon as the coal is mined it begins to absorb oxygen, rapidly at first, then more slowly. At first this action appears to be physical, but it soon becomes chemical, when the absorbed oxygen combines with the hydrogen of the coal to form water, and, with the carbon, to form carbonic acid. Heat intensifies the chemical action. Powdered stone coal fresh from the mine, heated to a temperature between 350 and 400 deg. F., increased in weight; although carbonic acid and aqueous vapour are disengaged, more weight of oxygen is absorbed. After a while a rather constant weight is obtained, and, by chemical analysis, the coal is then found to contain oxygen and hydrogen very nearly in the relative proportion in which they combine to water, which has not been the case in the fresh coal. The property of the coal thus rapidly to absorb oxygen depends mainly upon its proportion of free hydrogen. Of the Carbon of the coal only a few per cent (5 or 6) combine thus rapidly with the oxygen at the stated temperature, while the rest of the carbon is far more stable.

Different stone coals heated to the boiling-point of water until their weight remained constant, would absorb in a humid atmosphere at 60° F., from 2 to 7 per cent of water, and it was remarkable to observe that some solid pitch coal would absorb three times as much water as a soft laminated coal. The faculty of absorption could not be judged from the appearance of the coal, but coals from the same stratum exhibited considerable uniformity of behaviour. The coals which absorbed most water were also those which absorbed most oxygen. Twenty grm. coal absorbed in the first twenty-four hours after mining from 2 to 9 cubic centimetres oxygen. Stone coal absorbs carbonic acid even more eagerly than oxygen, taking up three times as much of it. At higher temperatures, the chemical action of the oxygen is increased, and a slow combustion takes place.

The influence of humidity on the deterioration of coal is complicated, and Dr. Richter's experiments did not lead to very definite results in that respect. Air-dry coal absorbs the oxygen far more rapidly than moist coal, and

eagerly, taking up at the same time some nitrogen from the air. On the other hand, humidity induces decomposi tion of the iron sulphuret contained in most coals, which in turn accelerates the chemical changes of the coal by creating heat, by causing it to split and slack, and probably, also, by inducing chemical action between the oxide of iron formed and the coal, if not between the oxygen and coal directly.

Light appears to exercise little influence. When coal has been exposed some time, and absorbs oxygen with little avidity, this absorption is a little greater in the dark. These were the principal results of Dr. Richter.

An interesting experiment was made some years ago in Germany to test the deterioration by exposure of Silesian gas coal. A quantity of coal slack was divided in three parts. One part was directly used in the gas factory, another after having been housed one month, and the third after one month's exposure in the yard. The relative proportions of gas obtained were 135, 111, 95. The losses by exposure were, therefore, 17.2 per cent and 29.5 per cent. The gas coke from the first lot was serviceable; from the second and third unserviceable.

It can hardly be doubted that this affinity of the oxygen for the coal has contributed much towards determining the quality of the coal which the different strata now present, but acting slowly in the course of ages, the effect has not been an apparent decomposition, but merely a difference of quality. The bituminous coking and gas producing coals have been least affected. They retain the largest proportion of hydrogen uncombined with oxygen and the least combined. The sinter or sand coals, which coke little or not at all, and furnish a poor gas, contain less hydrogen uncombined with oxygen, and more oxygen and hydrogen combined, than if they had been partly deteriorated by exposure. How little chemical equilibrium exists in a coal stratum is evident from the immense amount of carburetted hydrogen gas which is evolved in the coal mines, even in those which are not subject to dangerous accumulations of it in the form of fire-damp, and which in many, especially in deeper mines, can be heard escaping in minute bubbles from the sides of the rooms, making a peculiar noise. The quality of the roof and the quality and thickness of the superincumbent rock formations have exercised an important influence in determining the quality of the coal strata. Not seldom the deeper strata of a coal basin are the most bituminous ones. The more recent brown coals, the coals which are so extensively developed throughout the region of the Rocky Mountains, which are of cretaceous age, and present the appearance of stone coals, contain generally little hydrogen compared to their large proportion of oxygen. They should on that account not be apt to decompose readily, but the large amount of hygroscopic water which they contain, and their lack of cohesive strength, render many of them an easy prey to deterioration by exposure. I have seen many car-loads brought into this city (Salt Lake), of which the uppermost pieces, from an exposure of several days to the scorching sun and drying winds, were cracking and exfoliating very much like burnt lime in a moist atmosphere. These coals would certainly be of superior quality if they had been buried deeper in the bowels of the earth, and protected by heavy deposits of dense rock strata, which would have prevented the loss of so much of their bitumen, and rendered the access of oxygen more difficult. These coals are, however, not equally devoid of bitumen, and a locality in Sanpete Valley, U. T., presents a curious example of the influence of a solid casing. Near the village of Wales there is an outcrop of this brown coal, which is far more bituminous than the average. It is encased between solid beds of a slaty limestone, which forms a foot wall and roof of great stability. There is no clay seam or shale intervening. The whole thickness of the bed is about forty inches at this point, which appears to diminish to both sides, but it is not all coal. In its upper part it encloses several inches

of slate, and in its lower part an irregular seam of the same slaty limestone, from o to 10 inches in thickness. The coal itself is very solid, has a subconchoidal fracture, and, aside from the slate, contains a large proportion of ashes. Thus armour-plated against the inroads of decomposing agencies, it has retained considerable bituminous matter at the cost of purity. This coal is remarkable also on account of the vast number of small fresh water shells which are associated with it, and which must render it rich in phosphorus. Not only is the limestone above, below, and the coal full of these white shells, but the block slate is also crammed full of them, and even the coal itself near the slates.-Engineering and Mining Journal.

LIQUID GLUE PREPARED FROM SACCHARATE OF LIME.

A SOLUTION of 1 part of loaf-sugar in 3 parts of water, when spread on paper, imparts to it neither gloss nor strength, for the size does not adhere to the fingers when moistened. If, however, we add to the sugar the fourth part of its weight of slaked lime, and warm it to 145° to 165° F., then let it macerate some days, shaking it frequently, we shall find the greater part of the lime dissolved. The solution decanted from the lime sediment is then found to have the properties of mucilage, and a coat of it possesses gloss and firmness.

If we soak 3 parts of glue broken in small pieces in 12 to 15 parts of this saccharate of lime, then on warming it the glue dissolves rapidly, and remains liquid when cold without losing its strength, as glue does when treated with acid. Glue of any desirable consistency may be prepared by varying the amount of saccharate of lime added; the thicker glue keeps its muddy colour, the thin becomes clear on standing.

Gelatine dissolves in this solution of lime and sugar without previous soaking; even old gelatine, which has become insoluble in hot water, is soluble in this compound. This glue has great adhesiveness, and admits of very many uses; it cannot, of course, be used on colours that are injured by the lime, as, for example, chrome-yellow, Parisblue, zinc-green, Behringer's green and carmine. Ponceau made from carbolic acid is changed into a beautiful carmine colour. When warming the glue to dissolve it, a strong smell of glue is given off, but this is destroyed by a few drops of oil of lavender; a small admixture of 2 to 3 per cent of glycerine is also an advantage. Carbonic acid acts upon the lime when the glue is exposed a long time to the air, producing little white specks, without, however, affecting its adhesive and preservative power.— Journal of Applied Chemistry.

PROCEEDINGS OF SOCIETIES.

ROYAL IRISH ACADEMY.

MISCELLANEOUS.

Shaping Soft Rubber with a File.-We hear from Professor Morton, President of the Stevens Institute, that the ordinary thick sheet rubber used in making up lantern tanks and for many similar purposes, may be readily dressed into exact shape with a file, if only it is supported by being clamped between plates of wood or metal in the vice. The file is used dry, and in all respects as in working on wood or metal.

The Luminiferous Ether. Though compelled to think of space as unbounded, there is no mental necessity whether it is filled or empty must be decided by experito compel us to think of it either as filled or as empty; ment and observation. That it is not entirely void, the starry heavens declare, but the question still remains : Are the stars themselves hung in vacuo? Are the vast regions which surround them, and across which their light is propagated, absolutely empty? A century ago the answer to this question would have been, "No, for particles of light are incessantly shot through space." The reply of modern science is also negative, but on a somewhat different ground. In support of the conclusion able to offer proofs almost as cogent as those which can that the celestial spaces are occupied by matter, it is be adduced for the existence of an atmosphere round the earth. The notion of this medium must not be considered as a vague or fanciful conception on the part of scientific men. Of its reality, most of them are as convinced as they are of the existence of the sun and moon. The luminiferous ether has definite mechanical properties. It is almost infinitely more attenuated than any known gas, but its properties are those of a solid rather than of a gas. It resembles jelly rather than air. A body thus constituted may have its boundaries; but, although the ether may not be co-extensive with space, we at all events know that it extends as far as the most distant visible stars. In fact it is the vehicle of their light, and without it they could not be seen. This allpervading substance takes up their molecular tremors, and conveys them with inconceivable rapidity to our organs of visions. It is the transported shiver of bodies countless millions of miles distant which translates itself in human consciousness into the splendour of the firmament at night. If the ether have a boundary, masses of ponderable matter might be conceived to exist beyond it, but they could emit no light. Beyond the ether dark suns might burn; there, under proper conditions, combustion might be carried on; fuel might consume unseen, and metals be heated to fusion in invisible fires. A body, moreover, once heated there, would continue for ever molten. For, the loss of heat being simply the abstraction of molecular motion by the ether, where this medium is absent no cooling could occur. A sentient

being, on approaching a heated body in this region, would be conscious of no augmentation of temperature. The gradations of warmth dependent on the laws of radiation would not exist, and actual contact would first reveal the heat of an extra ethereal sun.-Tyndall.

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 halfyearly volumes of the CHEMICAL NEWS, with their copious indices, will, therefore, be equivalent to an English edition of the "Jahresberichte."

NOTE. All degrees of temperature are Centigrade, unless otherwise expressed.

Comptes Rendus Hebdomadaires des Séances de l'Academie des Sciences, December 23, 1872.

In addition to a series of papers strictly relating to other departments of physical sciences, this number contains the following original memoirs relating to chemistry:—

Action of Iodine upon some of the Hydrocarbons Belonging to the Aromatic Series.-P. Schutzenberger.-This essay contains the record of a series of experiments made with the view to ascertain the action of iodine under pressure (sealed tubes), and at a high temperature, upon certain hydrocarbons. Benzol gave a negative result; naphthaline was quite carbonised, but toluen is dehydrogenised, the result being the formation of new hydrocarbons-among these benzyltoluen, CH14-2C,H.-H.; and a red-coloured solid body, soluble in benzine and in chloride of carbon, fusion-point 100°, formula,2n(C14H11)=2(C,H ̧- H ̧).

Reciprocal Conversion of Inactive Tartaric and Racemic Acids; Preparation of Inactive Tartaric Acid.-E. Jungfleisch. -Reserved for full translation.

December 30, 1872.

This number contains the following origina papers and memoirs more particularly relating to chemistry :

On some Reactions of the Chlorides of Boron and Silicium. -L. Troost and P. Hautefeuille.-When the vapours of chloride of boron are caused to pass through a non-glazed porcelain tube at redheat, the chloride is partly decomposed, chlorides of aluminium and silicium are evolved, and borate of alumina formed in the tube. If the chloride of boron is made to pass through a red-hot glazed porcelain tube the glaze is acted upon, and there is also formed, in addition to the chlorides above named, double chloride of aluminium and potassium. Pure chloride of silicium does not act upon porcelain even at the highest temperature; but both this chloride and that of boron under the same conditions act upon many other substances, such as zirconia, titanic acid, &c., forming chlorides thereof.

Quantitative Estimation of Manganese in Iron Ores, PigIron, and Steel by a Colorimetric Process.-P. Pichard.-Reserved for translation, a remark also applying to thefollowing paper :Volumetric Estimation of Small Quantities of Arsenic and Antimony.-A. Houzeau.

Presence of Methyliac in Methyl-Nitric Ether and in Methylic Alcohol.-M. Lorin.-It appears that on testing samples of methyl-nitric ether and of methyl-alcohol, the author found therein a substance which on being treated with hydrochloric acid yielded methyliac hydrochlorate. The process of the operation is described at great length, and it further appears that the samples operated upon were relatively pure.

Use of Cupric Liquors for the Estimation of Sugar.-L. Possoz.-When the cupric liquors used for the estimation of sugar are either treated with carbonic acid or with alkaline bicarbonates, there is precipitated from these fluids some carbonate of copper, while another portion of copper remains in solution. This (tartrate of copper and potassa, or of soda + aikaline carbonates) is not decomposed by pure cane sugar at temperatures between 60 and 95°, but is readily decomposed by inverted sugars. The fluid freed from caustic alkalies cannot give rise to the errors lately mentioned in various periodicals.

Researches on the Spectrum of Chlorophyl.-J. Chautard.

Annalen der Chemie und Pharmacie, No. 1, 1873. On Sulphate of Iron Precipitated by Alcohol, and on the Quantity of Water Contained in the Double Sulphate of Iron and Ammonia, and of the Double Sulphate of Iron and Potassa,

L. Caro.-This paper, written chiefly to rectify some experiments known, viz., that the composition of protosulphate of iron precipitated made by Barckhausen and Rheineck, mainly confirms what is already by alcohol is the same as that of the crystallised salt; while, as regards the two other salts, Rheineck's statement as to their composition is proved to be erroneous.

On Hydrogen Shifting (Wasserstof Verschiebung) on the Carbon Skeleton (Kohlenstoff Skelet) of Organic Compounds. -W. Heintz. This essay, illustrated by a series of complex formulæ, is not well suited for abstraction.

Monatsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin, August, 1872.

This number contains no original papers relating to chemistry, but we quote the title of Dr. Vom Rath's paper on

The Crystallographic System of Leucite. - Illustrated by several engravings.

Annalen der Physik und Chemie, von Dr. J. C, Poggendorff, Nos. 11 and 12, 1872.

These numbers contain no original papers relating to chemistry.

Bulletin de la Société Chimique de Paris, December 1, 1872. The original papers in this number have been already abstracted from other French periodicals.

Le Moniteur Scientifique Quesneville, January, 1873. Anthracen and its Derivatives.-E. Kopp.-The continuation and end of this exhaustive essay treats on the modes of applying artificial alizarine and purpurine, native alizarine, and the extracts of madder. There are a large number of practical receipts and directions for the use of the dyer and calico printer.

Memoir on Two Acids Found in the Mother-Liquors of Coralline.-A. Commaille.-This essay, treating on parathionic and thioamylic acids, and on an acid isomeric with sulphamylic acid, is a full account of the author's researches already alluded to (see CHEMICAL NEWS, vol. xxvi., p. 300).

Method of Purification of Rosolic Acid.-Ch. Girard. In the introduction to this paper the author gives a resume of the methods by which pure phenol or cresylol may be converted into rosolic acid, while, further, the experiments of Wanklyn and Caro with rosaniline, and those of Liebermann with the same substance (the final result in each case being the formation of rosolic acid) are spoken of. The author next describes at length a rather complex process of purifying the rosolic acid obtained from either rosaniline or any of its salts by the aid of water under high pressure at 205°. The substances resulting from this reaction are first treated by the author with aniline, heat being applied. Thus there is formed azuline blue, which is first treated with hydrochloric acid, then washed with water, dried and reduced to powder; this is treated with caustic potassa. The insoluble residue is again treated with dilute hydrochloric acid, then washed with distilled water, and having been dried, the residue is treated with the vapours of either chloroform or crystallisable benzine; again dried, treated with alcohol, filtered, and the solution evaporated. The residue is treated, under pressure at 100°, with alcoholic potassa solution, whereby aniline is formed (from the triphenylic-rosaniline present in the matter), and rosolate of potassa, which, after the addition of water, is decomposed by an acid, yields flocculent rosolic acid. This is further purified, after washing and drying, by solution in boiling absolute alcohol; from the hot filtrate of that solution the pure rosolic acid is deposited on cooling in a crystalline state.

New Method of Preparing the Hair of Rabbits and Hares to be Used in Felt Hat Making, Without the Use of Mercury.M. Hillairet.-A detailed account of some newly-devised processes, by the application of which the use of mercury may be avoided in the preparation of felt.

Preservation of Timber and Wood by Means of Tar.-Dr. Quesneville. This essay contains a condensed account of the resuits of practical experiments made in France and Belgium by different persons to ascertain the value of tar as a preservative of timber, and the best methods of applying it.

Memoirs on the Estimation of Phosphoric Acid. — T• Schlæsing and G. Ville.

Bibliography.-Under this heading attention is called to the following work:-"Histoire de la Botanique, de la Minéralogie et de la Géologie Depuis les Temps les Plus Réculés jusqu'à nos Jours," par Dr. F. Hoefer, the eminent editor of the well known "History of Physics and Chemistry."

Although not belonging to chemistry, we call attention to the two following essays:

The Floods of the Seine.-H. Parville.-This memoir contains not only important historical, but hydrographical and geological information concerning the causes of the rapid rising of the rivers in eneral.