INORGANIC SUBSTANCES BY ANIMAL CHARCOAL.

BY F. WEPPEN.

FROM the fact that animal charcoal precipitates a number of very different colouring matters from their solutions, it was presumed that this effect was not limited to colouring matters, and the presumption has been substantiated by the following experiments, which show that animal charcoal likewise precipitates bitter substances, resins, and substances containing tannin. The charcoal used for these experiments was obtained from bone-black by repeatedly boiling it with muriatic acid; afterwards well washing it, and then exposing it to moderate red heat.

I. ORGANIC SUBSTANCES.

1. Bitter Substances.—Ten grains of the substance were digested with two ounces of boiling water, and the filtered infusion shaken with the charcoal, until the bitter taste had entirely disappeared.

A solution of two grains of extract of aloes in two ounces of water, became quite tasteless with forty grains of charcoal.

2. Resins.-One drachm of the tincture of guaiacum and of the tincture of jalap were respectively diluted with as much alcohol; the first required thirteen grains, and the latter twenty-five grains of charcoal to precipitate the resin contained therein to such a degree, that the solution became only very slightly clouded upon the addition of water.

3. Astringent Substances.-A solution of one grain of extract of nutgalls in half-an-ounce of water required twenty grains of charcoal; a solution of half-a-grain of pure tannin dissolved in half-an-ounce of water required ten grains of charcoal; an infusion of ten grains of rhatany root and the same quantity of cinchona bark in two ounces of water, required twenty grains of charcoal to deprive them of their power of reacting on the salts of iron.

II. INORGANIC SUBSTANCES.

That animal charcoal precipitates certain metallic salts from their solutions in water or spirit of wine, is a fact which has been long established. I find that probably all metallic solutions are similarly affected, though some require more charcoal than others. Moreover, this effect does not depend on the chemical constitution of the metallic oxide, whether its formula be M O or M2 03.

The following salts were subjected to experiment:

Sulphate of copper

" zinc

"protoxide of iron
"oxide of chromium

Nitrate of oxide of mercury

Acetate of lead

Emetic tartar

Chloride of tin

Corrosive sublimate

Acetate of the oxide of iron
Nitrate of nickel

On an average, thirty grains of charcoal were required for every grain of these salts, dissolved in halt an ounce of water; but, for reasons hereafter mentioned, it was difficult to precipitate them entirely, the addition of charcoal only rendering the reaction less distinct.

If caustic ammonia be added to those salts whose bases cannot be precipitated by ammonia, or which are redissolved by excess of the precipitant (copper, zinc, silver, lead n sugar of lead) much less charcoal is required;

and the precipitation takes place much sooner. Not merely basic metallic oxides, but also certain metallic acids are precipitated by charcoal; oxide of lead dissolved in caustic potash was precipitated by charcoal; also the acids from antimoniate of potash and tungstate of ammonia. On the other hand, no effect was obtained on arseniate and arsenite of soda; and arsenious acid dissolved in water could not be entirely precipitated by animal charcoal. Bichromate of potash and chromic acid were reduced by the charcoal, in the cold slowly but yet completely. The chromate of potash became converted into carbonate of potash. Furthermore, the charcoal precipitated iodide of mercury from the ammoniacal iodide of mercury; and sulphuret of antimony from the ammoniacal sulphuret of arsenic.

A solution of iodine in water or in iodide of potassium is quickly decolourized by charcoal; but it is impossible to precipitate sulphur from its solutions in alcohol or oil of turpentiine; for even after a large addition of charcoal, the filtered fluid heated over a silver plate still yielded traces of sulphuret of silver.

Salts having an alkaline base, as cream of tartar, ferrocyanide of potassium, gypsum, and alum, and also lime-water, appeared to be unaffected by charcoal; but a reaction takes place on chloride of barium, particularly if a few drops of caustic ammonia be added to the solution.

In the precipitation of metallic salts by charcoal, three circumstances may happen:-1. The salt may be absorbed without decomposition. 2. The oxide contained in the salt may be reduced; or 3. The salts may be precipitated in a basic state. With some of the salts (sulphate of the protoxide of iron and corrosive sublimate) the latter takes place. As soon as the charcoal begins to act, the solution of the salt becomes distinctly acid, and by quantitative examination, the greatest part of the acid will be again found in the fluid. This separation of the salts into acid and basic compounds is the reason why the last traces of the bases are so difficult to be removed by charcoal; for the acid which has become free prevents the perfect precipitation. Hence also, a salt to which some free acid has been added, is but little or not at all affected by charcoal. So also if we boil with acid the charcoal which has been used for precipitation, the precipitated oxides or basic salts contained therein, can almost entirely be extracted, though the last traces of the same resist the action of the acids.

Mulder mentions in his Physiology, that lead can be precipitated in the metallic state from sugar of lead, by means of charcoal. If this were the case, no oxide of lead could be extracted by boiling the washed charcoal in acetic acid. Whether easily reducible, metallic oxides, for example, oxide of silver, can be reduced to the metallic state by charcoal, I have not ascertained. It has lately been asserted that the precipitation of the metallic salts by charcoal depends on the calcareous salt, which cannot perfectly be extracted by the application of acids. If this were the case, by the application of a salt, whose acid forms a very easily soluble combination with lime, a calcareous salt would be found in the liquid standing over the charcoal.

In order to determine this I dissolved ten grains of corrosive sublimate in two ounces of water, and shook this with ten scruples of charcoal. The acid liquor was filtered, deprived of every trace of mercury by sulphuretted hydrogen, and evaporated. The last drops of the liquid certainly showed distinct traces of lime. The charcoal used in this experiment was then boiled with muriatic acid, washed, and again mixed with ten grains of a solution of corrosive sublimate. In both the second and third trials traces of a calcareous salt were found in the liquid. When the charcoal, which had been used in all three experiments, was deflagrated with nitrate of potash, and the saline mass dissolved in water, a very small residue only was obtained; which, moreover, was only partially soluble in muriatic acid. It, therefore, appeared to me improbable, that a salt of lime should be extracted out of it by means of a solution of corrosive sublimate, rather

than by means of muriatic acid. And, moreover, if this even had been the case, the contained calcareous salt would have been removed after I had three times treated the charcoal with corrosive sublimate. The calcareous salt, therefore, must have originated either from the water, or from the vessels, in which the fluid had been evaporated. In fact, after an equal quantity of water had been evaporated in a porcelain capsule, to a few drops, and only one drop of muriatic acid added, I obtained distinct evidence of the presence of lime on the addition of oxalate of ammonia. Moreover, as charcoal also precipitates substances, where the precipitation cannot depend on the presence of calcareous salts, as in the case of iodine, it is very improbable that the effect on metallic salts depends on the calcareous salts.Ann. der Chimie, Bd. lv., Heft 2.

POTATO DISEASE.

TO THE EDITOR OF THE PHARMACEUTICAL JOURNAL.

SIR, I trust you will not think the few remarks I am about to make on the potato disease to trespass on your space too much. I, like many others, was induced to try some remedy for the twofold purpose of preserving the seed and checking the disease. In the early part of November, I procured two sacks of potatoes, the one having grown on high land, the other on fen land. After sorting the whole, taking particular care to separate the diseased and those cut by the fork, I placed the sound potatoes in a dry loft on straw exposed to a current of air for a week; after that time, I placed them in large crates, in layers of potatoes and straw, exposing the sides to the full action of the sun and air daily. The diseased potatoes from the high land, I put into a mixture of whiting and water for about five minutes, then exposed them to dry for two days, and placed them in the same form as the others. The diseased potatoes of the fen land I exposed to chlorine gas for twelve hours (proposed by Mr. Tatershall), and after drying, laid them in saw-dust. I now find after six weeks trial, the whole of the potatoes are perfectly sound, including those placed in the whiting and water. Your obedient servant,

Bourn, December 15, 1845.

ROBERT M. MILLS.

ON THE POTATO DISEASE.

BY ANDREW URE, M.D., F.R.S.

THE vague and contradictory statements concerning the nature of this calamitous visitation of Providence, as well as the directions for the treatment and preservation of the tubers, generally impracticable and preposterous, which have recently issued in vast variety from the press, do little honour to economic chemistry. It is needless to notice all the notions and schemes which have either officially or spontaneously been projected. Only two of these deserve comment; the first, as coming from a great master in science; the second, as emanating from the Irish Commissioners.

Professor Liebig imagines the essence of the disease to consist in the conversion of the albumen, a usual constituent of healthy potatoes, into caseine, a principle which, by its great instability of composition, is supposed to cause the potato to putrefy rapidly. I have subjected this opinion to the test of experiment. Perfectly sound potatoes, as also diseased ones, were

sliced or grated, and separately digested in a very dilute alkaline ley at a blood heat. The infusions, when cool, being filtered and faintly acidulated with dilute acetic acid, afforded respectively a like proportion of caseine. looking flakes. It would thus appear, from this mode of testing, as prescribed by M. Dumas in the seventh volume of his Traité de Chimie, that sound potatoes contain as much caseine as unsound.

Professor Liebig's plan of preserving diseased potatoes is founded on the above notion, and consists in cutting them into slices one quarter of an inch thick and steeping them twenty-four or thirty-six hours in dilute sulphuric acid. On this proposal I need make no comments, as it has no chance of being practised beyond the precincts of Giessen.

In the Pharmaceutical Journal for October last, I inserted a few observations on diseased potatoes, chiefly with a view of showing, that till the putrefactive stage commences, the potato had the same acidulous reaction as in the sound state, but that then a portion of ammonia made its appearance, as was proved by its alkaline action on litmus paper, and by its coming over in distillation. That brief notice was written while I was at a distance from home on professional business, and where I had no means of prosecuting my experiments. At my first period of leisure since, I resumed my inquiries, and have obtained certain results which may probably be found useful, as well as interesting. Before entering into a detail of them, I shall shortly describe the constituents of sound potatoes, according to the most authentic analyses. Their average composition in 100 parts, according to Einhof and Lampadius, is-fibrous matter, 7; starch, 15; vegetable albumen, 1; gum, acids, and salts, 3.5; water 75. Besides these principles, Vauquelin, by his older and more minute analysis, discovered the following in minute quantities:-crystallizable asparagin; an azotised substance resembling gum : a resinous matter emitting an agreeable odour when heated; an extractive matter which blackens in the air; citric acid; citrates and phosphates of potash and lime.

The fibrous matter of potatoes is not of the same species as that of woody roots, but consists of a substance analogous to starch, which swells in water, becomes transparent, dissolves for the most part in dilute sulphuric acid, and affords gum and sugar, only by the action of concentrated sulphuric acid. In some of Einhof's experiments, the gummy matter which remained after evaporating the potato juice was saccharine, but he ascribed the formation of this sugar to an alteration produced on a portion of the gum in the course of analysis. Neither he, nor Lampadius, nor even Vauquelin, found sugar in sound potatoes. There can he no doubt, however, that from several causes, potatoes may become sweet-tasted, indicating that part of their starch is saccharified. Thus, by exposing them to repeated alternations of temperature, a few degrees below and above that of melting ice, the formation of sugar is so much promoted, that they grow soft with the production of a syrup of so rich a nature, that it will not permit the potatoes to solidify even when cooled several degrees below 32° Fahrenheit. This curious transmutation seems to depend, at least in its origin, upon a vital reaction; for when they are frozen very rapidly, no sugar is formed either during or after their thawing; but, on the contrary, potatoes so treated afford more starch than otherwise.

The nutritious quality of potatoes resides chiefly in the starch, fibrine, and albumen; the latter being essential to the formation of blood, Boussingault rates the feeding of a cow for twenty-four hours at fifteen kilogrammes (about thirty-three pounds avordupoise) of potatoes, and the quantity of azote in them at fifty grammes, orth part of their weight. This would give th part of azote in dried potatoes. Now, since these contain four times as much albumen as the moist ones do, we shall have four per cent. of albumen in them, according to the above analysis, which four parts coutain the whole of the azote in 100 parts of dried potatoes, amounting to th,

THE POTATO DISEASE.

or one and one-third per cent. But 100 parts of albumen, according to Dumas and Cahours, contain 15.75 of azote, and four will therefore contain only 0.65, being about one-half the proportion of azote assigned by Boussingault. Having, in the course of my frequently recurring analyses of guano, contrived a method of determining its proportion of azote, even to th of a grain, or half a milligramme, I have recently had recourse to this method in the examination of potatoes. When a portion of these, in a dry, pulverulent state, was subjected to ignition in contact with hydrate of soda and lime, 0.579 of azote were obtained from 100 parts of the potato; a number which accords well with that deduced from Dumas and Cahours' results, as applied to the proportion of albumen in potatoes, an accordance which seems to justify my determination. Potato, in its ordinary moist state, will hence contain about 0.015 of azote, or one and a half parts in a thousand. To this element, and the animal principles into which it enters, the nutritive quality of potatoes is to be ascribed, while their starch and starchy fibrine afford the fuel of animal temperature.

In the diseased potatoes, a portion of the starch is transformed into sugar, and of the albumen into an acrid offensive brown substance. If such tubers as are characterized by brown spots in the interior, and a thickened brown skin, both composed of fungous fibres, be grated or sliced, and exposed to pressure, either alone or with a little tepid water, the juice obtained will be found to have a mawkish sweet taste, followed by a sense of pungency on the tip of the tongue. If some of this juice be mixed with a little of Trommer's grape-sugar test (an alkalized solution of sulphate of copper) this blue-coloured mixture will change into a bright orange hue, slowly, in the cold, but rapidly on the application of a gentle heat, with a deposit of protoxide of copper. By means of a modification of that test, described by me in the Pharmaceutical Journal for July, 1842, I have ascertained the existence of about five per cent. of saccharine matter in diseased potatoes; yet by the same re-agent, which is sensible to th of a grain of sugar, I could observe none of it in perfectly sound potato. After satisfying myself, in this way, as to the presence of sugar in diseased potatoes, I proceeded to verify the fact by placing their expressed juice, as also their infusion, in contact with a little yeast, at a fermenting heat of from 80° to 90° Fahrenheit, and watched the resulting phenomena. A fermentative action soon began, and in an hour or two became so brisk as to throw up a thick, creamy froth, like that occurring with small-beer wort. thirty-six hours, the liquor having considerably diminished in specific gravity, At the end of was subjected to distillation, and yielded alcohol equivalent to about four per cent. of sugar in the potato. In order to obviate any chance of fallacy in these results, I requested Mr. Scanlan to repeat my fermentation experiments on a somewhat larger scale than mine, with diseased potatoes found in his own neighbourhood, at the extremity of London, opposite to my residence. He has accordingly made several similar researches, with like results, of which I shall give the particulars of one only. Two and a half pounds of the expressed juice of such potatoes as are now used solely for feeding cattle, corresponding to three and one-third pounds of the entire tubers, were mixed with a small portion of yeast, and set to ferment in half-filled bottles. The action soon became so vigorous that the barm rose to the brim of the bottles. At the end of thirty-six hours the liquor having become nearly tranquil, was distilled, and afforded 5000 water-grain measures of an alcoholic liquid, of specific gravity of 0.988, containing, by Tralle's table, eight per cent. of absolute alcohol, equivalent to sixteen of sugar. 800 grains, may be regarded as the quantity of sugar indicated by this expe16 X 50 = riment in three and a half pounds of the diseased potatoes, or in 23333 grains, being nearly three and a half per cent. In other samples I found, as above stated, results indicating considerably more sugar, the proportion being very variable, according to the state of the disease. The vinous spirit