until we reached the plain, and it would seem that none are formed except where the descent is but little, or the lava but imperfectly melted.

There is only one point more of which I will speak. I am not quite satisfied that there is a fissure in the side of the mountain, through which the lava made its exit to the surface. Those of our party who had seen the flow of 1840 and who had no doubt of a fissure in the side of the mountain then, think that there is no fissure in this case. I do not of course believe in the old theory of a perpendicular duct or pipe reaching down to the reservoir of lava, but it seems to me that the lava by the pressure of gases and steam works its way to the surface as the water of springs by hydraulic pressure. Hydraulic pressure also constitutes a part of the force which impels lava. Mauna Loa is full of caves, passages, &c., and very porous, and besides the lava, in case of this flow at least, could melt its way more or less, where it met obstructions. It may be, however, that there is a rent in the side of the mountain.

NOTE. We have received from Prof. Alexander of Honolulu a map giving the course of the lava, and enabling us to make a correction in the map published in the last number of this Journal. The course there given was copied from the "Commercial Advertiser" of Honolulu. It requires only that the current should be made to flow west-north-west from near its point of starting, and then on reaching the base of Hualalai, bend northwestward into the course given in the map.-EDS.

ART. IX.-On some points of Agricultural Science; by SAMUEL W. JOHNSON, Professor of Analytical and Agricultural Chemistry in the Yale Scientific School, and Chemist to the Connecticut State Agricultural Society.

The Absorptive properties of Soils.-It has long been vaguely known, that the soil possesses a remarkable power of absorbing a great variety of bodies. How the soil absorbs odors (more properly the volatile matters that give the sensation of odor) has often been seen in the case of garments upon which the fetor of the American skunk has fallen. The Indians long ago taught that they might be "sweetened" by burying them in the earth; and indeed we are told that these people sweeten the carcass of the skunk by the same process to render it fit for eating. Dogs and foxes bury bones and meat in the ground, and afterward exhume them in a state of comparative freedom from offensive odor.*

It is well known that some surfaces have a much greater power of attaching odors to them than others. Every person has observed that woolen garments retain smells longer than cotton or linen ones, and it appears that the color with which a cloth is dyed affects its retentiveness for some odors. It is a fact, as the

In the older treatises on agronomy we find allusion made to the power of soils to absorb gases, and this power, especially as exercised toward carbonic acid and ammonia, has been assumed to be of much agricultural significance, although the lack of precise experimental knowledge as to its extent, has been confessed and lamented.

The absorptive power of the soil not only for odors and gases, but also for fixed matters carried into it in a state of solution, is illustrated in certain commonly occurring instances. Thus the wells in densely populated cities, or in the vicinity of barn-yards, or filthy canals, remain sweet and pure for a greater or less period of time, though they must be constantly receiving waters that have been in contact with putrefying animal matters. The filtration of the foullest water through a thin stratum of loamy earth removes all unpleasant effluvium and taste.

In the year 1850 it became known through two interesting articles published in the Journal of the Royal Agricultural Society of England,* that the soil exerts an absorptive power toward certain substances, ammonia and potash especially, but not toward hydrochloric, nitric and sulphuric acids, so that if dilute solutions of hydrochlorate, nitrate, or sulphate of ammonia or potash are filtered through, or agitated with a certain quantity of soil, the salts are decomposed, the bases remain in insoluble combination with the soil, and the acids are found in the solution united for the most part to lime.

Previous to 1850, the absorbent power of the soil was explained as a result merely of the surface attraction of porous bodies. Thus Liebig in his "Chemistry applied to Agriculture and Physiology," referred the condensation of ammonia in soils, to the surface attraction of oxyd of iron, alumina and humus, and compared this power of soils to that exhibited by charcoal, which absorbs 90 times its volume of ammonia gas, and evolves it again on moistening with water. He also says, deciding from analogy but in the absence of experimental data, and erroneously, "the ammonia absorbed by the clay or ferruginous oxyds is separated by every shower of rain, and conveyed in solution to the soil."

The separation of organic odors and coloring matters from foul water by contact with earth, has been considered analogous to the action of animal charcoal, by which, for example, beer writer has personally observed, that when a skunk has emitted its stench in the cellar of a house, the odor clings most perceptibly to silver ware which has been buried among napkins in the recesses of a "chína closet" long after it has disappeared from every other article on the premises. It is probable that the soil, or some of its ingredients, "sweeten" a garment as above stated, by first effecting a transfer of the odorous matter from the surface of the fabric to its own surface, and then destroying it by oxydation in the same manner as operated by charcoal and platinum black. See note on p. 78.

* On the absorbent Power of Soils." By H. S. Thomson. Vol. xi, pp. 68-74; and "On the Power of Soils to absorb Manure." By J. Thomas Way, Consulting Chemist of the Roy. Ag. Society. Vol. xi, pp. 317-380; also, vol. xiii, pp. 123–142.

and wine may be deprived of odor,* color and taste, and to that of alumina which forms insoluble lakes with organic pigments.

Way, in his comprehensive investigations before alluded to, after studying separately as far as possible the absorptive effect of each ingredient of the soil, was led as a last resort to investigate the relations of the silicates to saline solutions. The simple silicates he found ineffectual and had recourse therefore to the complex silicates. He digested feldspar with solution of chlorid of ammonium but detected no reaction, and thence concluded that the fragments of granitic rocks could not perceptibly decompose saline solutions. In order to trace the action of such silicates as are formed to a small degree in the wet way in soils by the weathering of the granitic minerals, Way next prepared double silicates of alumina with the bases potash, soda, lime and ammonia respectively. In the first place he procured an alumina-potash- or alumina-soda-silicate, by precipitating the solu ble alkali-silicates with a salt of alumina; on digesting these double silicates with solutions of lime and ammonia, he succeeded in replacing the potash and soda by lime and ammonia, though but incompletely, for different preparations of his alu mina-ammonia-silicate contained but 451 to 5.64 per cent of ammonia instead of the quantity equivalent to the partly displaced alkali which, according to him, in case of the aluminasoda-silicate, should be 15-47 per cent.

Way gives as characteristic of this class of double silicates, that there is a regular order in which the commonest protoxyd bases replace each other. He arranges them in the following

series:

Soda-Potash-Lime-Magnesia-Ammonia: and according to him, potash can replace soda but not the other bases; while ammonia replaces them all: or each base replaces those ranged to its left in the above series, but none of those

* Several years ago Stenhouse found that the disinfecting property of charcoal depends, not merely upon the condensation in its pores of odorous matters, but also upon their destruction by the condensed oxygen with which doubtless, it is charged. The writer (after Stenhouse) has kept the carcass of a dead rat all summer long in the working room of the Yale Analytical Laboratory without its evolving any disagreeable effluvium, simply by burying it an inch deep in powdered charcoal. The only odor that is perceived, is a strong one of pure ammonia, and in time, all the putrefiable parts of the carcass disappear, the hair and bones only remaining. The animal matters enveloped in charcoal (or other highly porous body capable of con densing oxygen, as platinum black or platinum sponge; probably also most soils, especially those rich in humus) are completely oxydized to water, carbonic arid and ammonia (free nitrogen ?), without the appearance of the intermediate and fetid products that occur in putrefaction. The sweetening of meat by charcoal (or earth?) consists in the oxydation (eremecausis) of the putrefying surface. Stenhouse found that platinized charcoal (charcoal ignited after moistening with chlorid of platinum) makes an excellent escharotic and disinfectant for foul ulcers, and latterly the surgeon is employing permanganate of potash-an energetic oxydizing agent-for the same purpose.

SECOND SERIES, VOL. XXVIII, No. 82.—JULY, 1859.

on its right. Way remarks, that "of course the reverse of this action cannot occur." Prof. Liebig (Ann. de Chem. u. Phar., xciv, 880) has drawn attention to the fact that Way directly contradicts himself in describing the preparation of the potashalumina-silicate, which may be obtained by digesting either the lime-alumina or soda-alumina-silicate in nitrate or sulphate of potash, when the soda or lime is dissolved out and replaced by potash.

Way was doubtless led into the error of assuming a fixed order of replacements by considering these exchanges of bases as regulated after the ordinary manifestations of chemical affinity. His own experiments abundantly show that among these silicates there is no inflexible order of decomposition, nor any complete replacements.

Liebig, in the paper just cited, was led from this contradiction and from other considerations, to reject the conclusions of Way, especially as there was no direct proof that these double silicates exist in soils.

The recent researches of Eichhorn, "Ueber die Einwirkung verdünnter Salzlösungen auf Ackererde," (Landwirthschaftliches Centralblatt, 1858, ii, 169, and Pogg. Ann., No. 9, 1858,) have cleared up the discrepancies of Way's investigation (which is itself one of remarkable interest), and have confirmed and explained his facts.

As Way's artificial silicates contained about 12 per cent of water, the happy thought occurred to Eichhorn to test the action of saline solutions on native hydrous silicates. He accordingly instituted some trials on chabazite and natrolite, an abstract of which is here given.

On digesting finely pulverized chabazite with dilute solutions of chlorids of potassium, sodium, ammonium, lithium, barium, strontium, calcium, magnesium, and zinc, sulphate of magnesia, carbonates of soda and ammonia, and nitrate of cadmium, he found in every case that the basic element of these salts became a part of the silicate, while lime passed into the solution. The rapidity of the replacement varied exceedingly. The alkalichlorids reacted evidently in two or three days. Chlorid of barium and nitrate of cadmium were slower in their effect. Chlorids of zinc and strontium at first, appeared not to react; but after twelve days, lime was found in the solution. Chlorid of magnesium was still tardier in replacing lime.

Four grams of powdered chabazite were digested with 4 grams chlorid of sodium and 400 cubic centimeters water for 10 days. The composition of the original mineral (1), and of the same after the action of chlorid of sodium (II), were as follows:

Nearly one-half the lime of the original mineral is replaced by soda. A loss of water also has occurred. The solution separated from the mineral, contained nothing but soda, lime and chlorine, and the latter in precisely its original quantity.

By acting on chabazite with dilute chlorid of ammonium (10 grams to 500 c. c. water) for 10 days, the mineral was altered, and contained 3.33 per cent of ammonia. Digested 21 days, the mineral, dried at 212°, yielded 6-94 per cent of ammonia, and also had lost water.

These ammonia-chabazites lost no ammonia at 212°, it escaped only when the heat was raised so high that water began to be expelled; treated with warm solution of potash it was immedi ately evolved. The silicate appears to be slightly soluble in distilled water, the solution giving with solution of iodid of mercury in iodid of potassium, the yellow coloration indicative of ammonia.

As in the instances above cited, there occurred but a partial replacement of lime. Eichhorn made corresponding trials with solutions of carbonates of soda and ammonia, in order to ascertain whether the formation of a soluble salt of the displaced base limited the reaction; but the results were substantially the same as before, as shown by analyzing the residue after removing carbonate of lime by digestion in dilute acetic acid.

Eichhorn found that the artificial soda-chabazite reëxchanged soda for lime when digested in a solution of chlorid of calcium; in solution of chlorid of potassium both soda and lime were separated from it and replaced by potash. So, the ammoniachabazite in solution of chlorid of calcium, exchanged ammonia for lime, and in solutions of chlorids of potassium and sodium, both ammonia and lime passed into the liquid. The ammoniachabazite in solution of sulphate of magnesia, lost ammonia but not lime, though doubtless the latter base would have been found in the liquid had the digestion been continued longer.

It thus appears that in the case of chabazite all the protoxyd bases* may mutually replace each other, time being the only

* Eichhorn's observations indicate that the combined (basic?) water of a silicate is also liable to be increased or removed. May not the small amount of water of many specimens of properly anhydrous minerals be thus acquired? May not in some cases the loss by ignition in minerals, be due to ammonia that has entered into combination in the same manner?