work had been sent to the press at Stockholm. | many centuries in a damp vault, the issues from The sixth volume of the French translation, from which the following extract is translated into English, was printed in 1832. It is not known whether the original work is in this country.

The following passages contain the opinions of Berzelius, and of other chemists, on humin, and humic acids, or as called here, geine and geic acid, and which were referred to in the quotation from Rennie, at page 28. It will be left to the reader to decide, how far my views of acid soils are supported by these opinions of chemists, founded upon chemical analyses of the substances in question. It is proper to state, that this new doctrine of geic or humic acid has not passed uncontroverted. It is altogether denied by Raspail, a French chemist, and who is a later writer than Berzelius.

Extracts translated from the Traite de Chimie.

which were stopped up by earth, and of which the existence was forgotten, until by chance it was again discovered. The grains had preserved their form, and the brightness of their outside skin; but they were black, and were reduced by the slightest pressure to a black powder. The water with which they were boiled was colored yellow, and it left, after being evaporated, a saline mass of a brownish yellow, which burnt with slight explosion when heated, and which, besides the substance cited, soluble in water, contained nitrate of potash, nitrate of lime, and a little of the muriates of potash and of lime. The nitrates were the result of the oxydation of the nitrogen contained in the gluten and vegetable albumen, and of the combination of the nitric acid thus produced, with the bases previously combined with vegetable acids. The weight of this mass soluble in water,

PRODUCTS OF PUTREFACTION AT THE SUR- including the salts and all the other principles, did

FACE OF THE EARTH.

Mould [terreau.]

The vegetable matters which rot at the surface of the earth, finish by leaving a blackish brown pulverulent mass, which has received the name of mould, [humus.]

All the vegetation of a year, which dies at the arrival of winter, is converted by degrees to mould, which is mixed with the earth in which the plant grew: whence it comes that the extreme surface of the earth contains a greater or less proportion of mould, which serves for the nutriment of the succeeding growth of plants. This mould, such as it is found in the earth, is often mingled with the products of a less advanced putrefaction, or even with vegetable parts not changed, principally, a great quantity of small roots. If we examine the mould, such as it is found in cultivated soils, it is found to be in a mass very much mixed; but it is always possible to extract the parts which characterize mould.

*

not exceed 1 per cent. of the weight of the black grain. When the part insoluble in water was boiled in alcohol, a small trace of a brown substance was taken up, which remained after evaporating the alcohol, and had the consistence of wax. The mass, exhausted of its soluble parts by boiling water and alcohol, was then heated slowly with a weak solution of caustic potash, which became saturated and colored of a blackish brown; and this treatment was continued as long as new potash lie took up any thing. This substance was precipitated from the solution by an acid: it was the body similar to apotheme which has already been mentioned, and of which the weight amounted to 26 per cent. The portion of matter insoluble in the alkali preserved the same appearance. This exposed to the action of diluted muriatic acid, yielded to it a certain quantity of line, of oxide of iron, and of phosphate of lime. The residue was again acted on by potash, which took up a new and very large proportion of the body similar to apotheme. This was, after that, combined with lime, and resisted in that state the action of potash. This calcareous combination amounted to 42 hundredths. The 30 per cent. remaining consisted of a black carbonaceous matter, insoluble in the solvent used.

During the transformation of the vegetable matters to mould, the first portion of their mass is changed into a brownish black substance, which presents all the characters of apotheme, when we have separated from it the unaltered extract, which the apotheme draws with it. The salts of such If cultivated soil is treated in the same manner, acids as are of organic origin, contained in the ve- similar results will be obtained, with this difference, getable matter, are destroyed, so that the elements that the earthy matter of the soil is found mixed of the acid are resolved into water and carbonic with the products which are obtained, whilst no acid, whilst the base is combined with the sub-soluble salts are met with, they being generally stance analogous to apotheme, which makes part carried off by the rains. of the mould. The salts of acids of mineral origin are preserved, unless they are soluble, in which case the rain carries them off. In addition, mould contains a,substance but slightly soluble in water, which colors the liquid yellow, and a carbonaceous substance which is entirely insoluble, and which appears to be one of the products of a destruction, still more advanced, of organic matters.

To give an example of a completed formation of a mould of vegetable origin, I shall here state the results of an analysis to which Bracannot submited some wheat, which had remained during

*What Berzelius calls apotheme, is "a deposite ghly soluble in water, produced in an aqueous solution of vegetable extract during slow evaporation, and certaining a larger proportion of carbon, than does an equal weight of extract."

To describe the constituent principles of mould, it is necessary to designate them by particular names. I will then call extract of mould the body soluble in water, and I will give the name of geine* to the matter similar to apotheme, which constitutes the principal mass of mould. As to the coally substance insoluble in water, alcohol, acids and alkalis, I will designate it by the name of carbonaceous mould.

Extract of mould.

We obtain this substance by drawing it from the mould by the action of cold water, which becomes thereby colored yellow, and which leaves after evaporation, a yellow extract of a bitter taste, and from which some geine is separated when it

*Or kumin, as termed by other authors.

is again acted on by water. If this solution is thirds of its weight of the precipitated mass. left to evaporate spontaneously, in contact with These acid properties belong in part to the geine, air, it becomes covered with an insoluble pellicle, which owes them to the action of the alkali, and and when a certain degree of concentration has which may, in this case, be called geic acid; they been reached, the liquor becomes turbid. The ought to be in part attributed to a combination of solution is precipitated by the salts of tin and of the geine with the precipitated acid. According lead: after the precipitation, the liquor is without to Einhoff, it is the latter case which is really precolor. According to Korte, the sulphuretted hy-sented, and the acid cannot be carried off, but with drogen gas precipitates it also. This extractive the aid of an alkali. Sprengel, on the other hand, matter is contained in the water of many springs and streams. The water of the springs of Porla in Westrogotha, contains so great a quantity that it is colored yellow. When the iron contained in this water is oxydized from the air, the extract of mould is precipitated with the oxide of iron, and the water becomes clear.

Geine.

pretends to have freed the geine, by prolonged washing, from the muriatic acid which had served to precipitate it: and to make certain the absence of the muriatic acid, he has mixed the washed geine with a little nitrate of silver. After evaporation to dryness, and calcination, the residue, treated by nitric acid, was dissolved, without leaving any muriate of silver. But as muriate of silver, like the other salts of silver, is reduced to a This substance has received different names. metallic state by bodies containing carbon and Bracannot has given to it the name of ulmin, for hydrogen, and carbon itself effects the same reasons which I have exhibited and opposed in a change when disengaged along with water, this former part of this work. Dobereiner and Spren-result proves nothing. In general, in the descripgel gave to it the name of acid of humus, because it combines with the earths and alkalis. But for the same reason we might give the name of acid to more than the half of all vegetable bodies.

tions of geine, they have attributed the properties of that which has been changed by the action of an alkali, to the geine which has not been altered. The geine which reddens vegetable blues, is the Geine does not exist in vegetable earth only; same, whatever may have been the acid which soot contains it also, and according to Bracannot, served for its precipitation. Its saturated aqucous it is formed when the saw-dust of wood is exposed solution is of a yellowish brown, and the combito the action of caustic potash. It is almost im- nation is precipitated anew by acids, excepting possible to obtain geine in a state of purity. One the carbonic, and the sulphuretted hydrogen. Colpart of the geine which is met with in a natural lected upon a filter, it is presented under the form state, is in combination with bases; but when we of a gelatinous mass, of a taste slightly acid, asattempt to remove these by an acid, the geine tringent-and by drying, it contracts strongly, and combines in part with the excess of acid, and ac- forms clots of a deep brown, almost black, with a quires itself (in part) the property of reddening vitreous fracture, and which are not dissolved vegetable blues. Geine possesses all the proper- again in water after being once completely dried. ties of apotheme, and it is produced like other The aqueous solution of the acid geine, is precipiapothemes; that is to say, by the action of the air tated by the salts of lead, of tin, and of iron; but on dissolved extract of mould. In its natural state is not disturbed by gelatine, albumen, starch, gum, it does not act chemically, either like the acids or tannin, or solution of soap. According to Bracanthe alkalis, nor does it have any effect on the color not, it is precipitated by a mixture of the solution of vegetable blues. It is but slightly soluble in of gelatine and gallic acid. The dried geine is water, which it colors of a pale yellow; is still less dissolved with difficulty, and incompletely, in alsoluble in alcohol, and insoluble in ether. Ex- cohol. The solution reddens vegetable blues, posed to the action of heat it takes fire, burns at whilst the part not dissolved is without this power, first with flame, then without flame like spunk, though it still preserves the property of combining spreading a peculiar odor, something like that of with potash. Geine is destroyed by concentrated burning peat. Submitted to dry distillation, it is acids. The sulphuric acid dissolves it, taking at decomposed, gives half its weight of a charcoal the same time a black color, carbonizing it, disenhaving a metallic lustre, of empyreumatic oil, an gaging sulphurous acid gas, and leaving for resiacid water containing acetic acid and sometimes due the ordinary products which result from the ammonia, some carburetted hydrogen, and a little action of this acid. By the addition of sur-oxide carbonic acid gas. If geine is held suspended in (or black oxide) of manganese, carbonic acid gas water, through which a current of chlorine is pas-is disengaged. The nitric acid dissolves and desed, this whitens it, and precipitates a white resin- composes geine, with a disengagement of nitric like substance. Iodine is without action on it. oxide gas, and carbonic acid gas. If the solution If we add an acid to an alkaline solution of geine, is evaporated to the consistence of sirop, and then the geine is precipitated. If the whole of the mixed with water, there is precipitated a peculiar geine is not precipitated, that part which is pre- bitter substance in powder, and there are found in cipitated retains in combination a small portion of the solution, artificial tannin and oxalic acid. the base, and leaves, when it is burnt, a small quantity of alkaline ashes. If, on the contrary, an excess of acid is poured into the alkaline solution, the liquor is discolored, and the precipitated geine strongly reddens vegetable blues, a property which cannot be removed by placing the geine on a filter, and pouring water upon it. So long as the liquor which passes through the filter contains free acid, it is not colored; then it begins to be colored, and finally it dissolves as much as two

Geine forms soluble combinations with alkalis. When an excess of geine is used, the caustic alkalis are so neutralized by this substance, that they lose their peculiar chemical action and properties. In this respect geine agrees with gluten, vegetable albumen, the brown of indigo, the sugar of liquor ice, apotheme, and other bodies not acid. Dunng the evaporation, the solution furnishes a black mass, which acquires lustre by complete drying, and splits, and is easily reduced to a powder. It

is re-dissolved in water, its taste is weak, bitter | from the alkaline solution, in the state of acid and disagreeable. Caustic ammonia gives a like geine. When cold, the sulphuric acid has but mass, soluble in water, which gives up, during little effect on it. According to Bracannot, the evaporation, the excess of alkali employed. Geine nitric acid converts it, at a gentle heat, to a brown is not dissolved always in alkaline carbonates; liquor, in which water produces a precipitate of a when it is so dissolved, these carbonates are trans- chocolate color, which possesses the properties of formed, half into geates, half into bi-carbonates. acid geine, and is dissolved without residue, in the When the solution is boiled, the bi-carbonate is alkalis. decomposed with disengagement of carbonic acid gas, and in this manner the geine drives off all the carbonic acid. If a solution of geine in carbonate of ammonia, is evaporated, a residue is obtained containing neutralized geate of ammonia. The solution of geine in caustic potash in excess, absorbs oxygen from the air, and at the end of some time, the alkali is in part carbonated.

Soil [terre végétale.]

It is the mixture of these several substances with the upper layer of the surface of the earth, which constitutes the vegetable earth, or soil, properly so called. Arable land is a bed of this soil, placed upon a bed of earth which contains no mould. Its fertility depends upon the quantity of mould which it contains. Growing plants continually diminish the quantity of geine contained in the soil; and when the plants are carried off from the soil on which they grew, which happens almost always with cultivated land, it is finally exhausted to that degree as to produce nothing. It is on this account that it is necessary to manure land. The matters discharged and left by animals, or the barn-yard manure which is used for this purpose, are by degrees converted into geine, and thus replace the matters dissipated by vegetation. Botanists who have directed their attention to vegetable physiology, have remarked that the plants vegetate well enough without geine, until the time arrives for them to commence their sexual functions. But as soon as these are ended, and the fruit begins to be developed, the plants absorb a great quantity of the nutritive principles contained in the soil, and if these are not in the soil, the flower falls without forming any fruit. The experiments to which Th. de Saussure has submitted soil, [terre végétale] appear to demonstrate that the three constituent principles of mould, may be converted the one to the other, under the alternately preponderating influence of air and water. Water converts to the extract of mould a part of the insoluble geine contained in the soil, and this transformation extends more and more, so that finally the greater part of the geine becomes

Geine forms with the alkaline earths pulverulent combinations but little soluble, which have an external resemblance to geine. The best means for obtaining them, is to mix a solution of the geate of ammonia, with the solution of an earthy salt; the combination of the geine with the earth is precipitated, and may be separated by filtration, from the supernatant fluid. In the humid state, these compounds are slightly soluble in water. According to the experiments of Sprengel, one part of geate of barytes is dissolved in 5200 parts of water, one part of geate of lime is soluble in 2000 parts of water, and one part of geate of magnesia, in 160 parts of water, cold. These same compounds require for their solution, rather smaller proportions of boiling water. After having been completely dried, they will no more dissolve. In the air, the base is combined in part with carbonic acid, and the carbonate which results therefrom, remains in the state of mixture with a combination of geine, and of a base analogous to a super-salt. The alkaline carbonates decompose the earthy geates; they dissolve the geine, and leave the base in the state of carbonate. According to Sprengel, the geates of lime and magnesia are dissolved in the caustic fixed alkalis, and in the carbonate of ammonia. Other chemists have not arrived at the same result; and according to them, the geate of potash, acted on by the hydrate of lime, precipitates all the geine. The geate of alumina is pre-soluble. In contact with the air, the dissolved cipitated when a solution of alum is mixed with a solution of geate of potash, or of ammonia. This compound is dissolved in 4200 parts of cold water. In the moist state it is dissolved easily, and in abundance, in the alkaline carbonates and hydrates, and even in ammonia. According to Sprengel, it resists the decomposing action of acids, so that it is difficult to extract from it geine exempt from alumine. A combination is obtained having an excess of alumine, by digesting a solution of the geate of ammonia with hydrate of alumina. *

*

*

Carbonaceous mould.

matter passes again to the state of geine. The carbonaceous mould which changes a part of the air into carbonic acid, is itself changed by air into geine, and into the extract of mould, and it is upon this transformation that appear to depend in part the advantages derived from the tillage of the soil, which is divided by the action of the plough, and exposed to the immediate influence of the air. In this manner all the parts of the soil contribute to nutrition; whilst it is probable that the solution of the extract of mould, that of the geate of lime, and perhaps also that of the geate of alumine, are immediately absorbed by the roots. During a heavy rain, this solution penetrates the interior, and often to very deep beds of the steril earth; but notwithstanding that, it is not lost to vegetable life: for the roots of trees seek it, and bring it back as matter suitable for their nourishment.

The substance to which this name has been given has been but little examined. It is insoTuble in alkaline liquors. Its color is a brown, almost black. Placed in contact with a body in combustion, it takes fire, and burns with- Experience has demonstrated that quicklime, out thame like spunk. According to the experi-and the carbonate of lime, mingled with the soil, ments of Th. de Saussure, carbonaceous mould favor the vegetation produced thereon. Chemistry combines with the oxygen of the air, and forms has not yet explained, in a satisfactory manner, carbonic acid gas, and when it is left a long time the power which lime thus exerts; however, it is exposed to air and water, it becomes by slow de-known that when the soil contains this alkaline grees soluble in alkalis. The acids precipitate it earth, or, in its place, ashes only, the mould is

quickly consumed, and vegetation becomes more acid liquid, containing the acetate of ammonia; rich in proportion. It has thence been concluded and when it is distilled, after having mixed it with that lime acts, partly in exciting the plant to great-water, a liquid product is obtained which reddens er activity, and partly in rendering more soluble vegetable blues, and likewise contains acetate of the principles of the soil, which are absorbed by ammonia. In opposition to Einhof, Sprengel afthe roots when dissolved in the water which the firms that the acid geine is produced only for the earth has imbibed. Lime is not then a true [or want of bases, and that its acid action proceeds alimentary] manure. It contributes only to pro- only from the geic acid which it contains, and not mote and hasten the absorption of the principles from the presence of a foreign acid. De Pontin which serve to nourish the plant; and that lime has made the analysis of an arid* soil taken from may be serviceable, it is necessary to introduce the plain of Eckerud in the government of Elfsinto the soil, improved by lime, materials proper burg in Sweden, and found that the geine had to furnish new quantities of mould. The lime, or there combined with the malic, acetic, and phosthe alkali contained in ashes, acts also in hastening phoric acids. The dissolving of the soluble printhe change of organic matters to mould. ciples of the soil in boiling water, left to be de

It is known by experience, that gypsum also posited, when the hydrate of lime was mixed augments the fertility of the earth, especially when therein, these acids as well as geine, so that there leguminous plants are cultivated. It is not proba- was found afterwards in the water only traces of ble that this neutral salt acts in the same manner the acetate and hydrate of lime. But when a as lime, and we are ignorant of what is its mode current of carbonic acid gas was made to pass of acting. through this precipitate steeped in water, the geine Soil [terre végétale] possesses the property of remained, without dissolving, in combination with being able to retain as much as three-fourths of the carbonate of lime produced, while there was its weight of water without appearing moist, and formed a solution slightly yellowish, which left, like charcoal, it condenses atmospheric humidity. after evaporation, a residue of calcareous salts. It owes this property to the geine which it con- This residue was treated by alcohol, which took tains, which is one of the substances which, of all up a certain quantity of acetate of lime, and left known, absorbs moisture with most energy. a salt of lime of a gummy appearance, which was Mould [terreau] can absorb double its weight of soluble in water, and possessed the properties of water, without appearing moist; and after being the malate of lime. In burning the geate of lime, dried, it draws from the air, in less than twenty- and taking up the residue by muriatic acid, there four hours, a quantity of water, which may vary was obtained a solution which, when treated by according to the humidity of the atmosphere, from ammonia, gave a small precipitate of phosphate 80 to 100 per cent. of its weight. This property of lime. The greater part of the acid geine was depends upon its light and dust-like consistence; dissolved in the carbonate of ammonia. Hydrate and geine, of which the fracture becomes vitreous of lime was poured into the solution, which prefrom its course of chemical treatment, is deprived cipitated the geine without leaving in solution a of this physical property, which is of the utmost salt of lime. But when after having washed the importance to vegetable life. For, in consequence precipitate, it was calcined, and the residue treated of this property, mould retains water in the earth with muriatic acid, there was obtained a solution, and obstructs its evaporation; and it is probably which, after the expulsion of the carbonic acid, this water which maintains the extremities of the gave with ammonia an abundant precipitate of roots in the state to perform their functions. the phosphate of lime. These experiments confirm those given by Einhof.

It is usual to divide soil into fertile earth, and acid earth. The first is very common-the se- An arid soil becomes fertile when there is cond presents itself but rarely. It produces no- mixed with it lime, or ashes and earth, inasmuch thing, unless it be mosses: it is in marshy places as the soil consists principally of geine. The rethat it is ordinarily found. It is in general com- port of Sprengel, according to which, it [this chaposed in the same manner as fertile earth; but racter of soil] is produced in consequence of the whilst in the latter the geine is united with lime, absence of the bases which are found in fertile and perhaps with other bases besides, it is, in the earth, is certainly true; but it does not follow from acid earth, combined with acids, which, according that, that it owes its acidity solely to the acid nato Einhof, are the phosphoric and acetic acids. It ture of the geine. The ashes of arid* soil always is for this reason that it has the property of red- contain a great quantity of silex. dening vegetable blues, and that it gives, by calcination, ashes which contain phosphoric acid. To dry distillation, it yields a great quantity of an

*This is still more strange, that so abrupt a translation should be made from acid, to arid soils and in such manner as to induce the belief that the change was not owing to the author-but to an error of the press. But It is not a little strange to say it is "usual [dans though this mistake would be as likely to occur in l'usage] to divide soils into fertile earth and acid earth," French as almost any other, (only one letter bewhen the acid nature of any, has been treated by Ber- ing different in the words acide and aride—) still it is zelius as a new discovery, and of which the truth is difficult to believe that this same error should he e not admitted by all of those who had taken the sub- been made and left to stand three times in this and the ject into consideration. If this division had indeed next page, where "arid" soils are named, and are been usual, there would have been no want of numer- marked as above. The French translation is said to ous authorities (whatever might be their value) for contain numerous typographical errors. I leave others the acidity of soil, to decide whether these are among the number of pot.

11

THE STATEMENTS OF BRITISH AUTHORS ON open the land it is laid on, and not bind; it may be