it is not found upon anything else than dry wood, or only the consequence? I laid drawings of the ergot before the Assembly of Naturalists, at Florence (1841), in which the grains at the point had sprouted out into three leaves; an additional reason in favour of the ergot being only a monstrosity. It still remains to be ascertained, whether the excrescence only occurs on the scutellum. The fungus, which Quekett has very well described, is an Oidium. It is well that we can get rid of such an abominable term as Ergotætia, badly formed as it is from the Greek and the French. The observations on the different modes of propagation are very interesting; it is a question, however, whether they are not the result of an optical illusion."

We are not disposed to defend the generic term Ergotalia; though we by no means agree with the German botanists in their rigid adhesion to the Linnæan canons on nomenclature; as we have always thought "that it is of little real importance what name an object bears, provided it serves to distinguish that object from everything else."

The assertion that Quekett's fungus is an Oidium is not new. We heard it made, soon after the appearance of Mr. Quekett's paper, by a celebrated English fungologist.

Link adopts F. Bauer's notion that the ergot is a monstrosity; Quekett, on the other hand, contends that it is a deformity caused by the influence of a parasitic plant. In favour of the latter opinion may be urged the fact that the parasite has been detected in every ergotized grass which has been examined: on this point, English, French, and German writers are agreed. Surely, then, its presence cannot be said to be accidental? Its presence on other parts of the plant than the ovary is no argu ment against this opinion-indeed, Mr. Quekett admits that it may grow anywhere; but it only gives rise to ergot when it enters the plant and arrives at the ovarium.

There is one very strong fact in favour of Mr. Quekett's opinion, and with which Link appears to be unacquainted. We refer now to the power possessed by this fungus of infecting healthy grains of corn, and of ergotizing them. This fact was ascertained by Mr. Quekett subsequently to the publication of his paper in the Linnæan Transactions; but an account of his experiments was published in the London Medical Gazette, for the 8th of October, 1841.

Twelve healthy grains of rye, of wheat, and of barley, all grown in neighbouring fields in Surrey, were placed in a little water in a plate, and a few ergots of wheat added. The sporidia of the fungus adhering to the latter were brushed off into the plate by camel's hair pencil, and the ergots of wheat subsequently removed. Another set of healthy grains were then treated in the same way with the sporidia of the fungus obtained from the ergot of Elymus sabulosus. The two sets of grains were then covered with glass shades, and in a few days germination commenced. Subsequently the young plants were placed in the

ground; but only four of rye, three of barley, and four of wheat grew, and became perfect plants. Of these, every one of the rye, and one of the barley plants were ergotized; but the wheat escaped!

Link's argument for the monstrous nature of ergot, founded on the sprouting out of three leaves from it, appears to us to carry with it little weight. The same occurrence may happen to a deformed as well as to a monstrous growth.

It is scarcely necessary to reply to the doubt raised by Link, whether the observations on the different modes of the propagation of the fungus are not the result of an optical illusion. Mr. Quekett is too well known as a skilful and experienced microscopist to leave any doubt on this point, in the minds of English observers.

OBSERVATIONS ON DR. BIRKBECK NEVINS' TEST

FOR ASCERTAINING

P.

THE PURITY OF DISULPHATE OF QUININE.

BY G. M. MOWBRAY,

Fellow of the Royal Medico-Botanical Society, Member of the Chemical Society, M. P. S., &c.

THE following test has been suggested by Dr. Birkbeck Nevins, as appropriate for readily ascertaining the purity of disulphate of quinine.

"To one or two grains of the suspected salt✶ add three or four drops of sulphuric acid, in a white evaporating dish, and twice as many drops of water; if the salt contains either starch or fatty matters they will remain; whilst, if they are absent, the whole will be dissolved. Let heat be next applied to the solution, and, as it becomes concentrated, the acid will char any sugar which may be present, which will be indicated by a black stain round the edge of the solution, and the whole will speedily assume the same colour."

Allow me to submit that this test is perfectly valueless, and for the following reasons:-Dr. Nevins appears to have overlooked a fact well known to Chemists, whose investigations have been directed to organic compounds, that salts may be readily recognised as belonging either to the organic or inorganic class by heating on platina, if the compound under examination, after heating, yields a carbonaceous residue, then it belongs to the former class; if a whitish ash be left after ignition, then an inorganic compound has been operated upon. Now Dr. Nevins directs us to add sulphuric acid to the disulphate, the effect of this is to convert the salt into the soluble sulphate, and on the

If the acid be added first, the quinine will not be dissolved by the subsequent addition of water; the water should first be added, and then the acid, as many dispensing Chemists have found to their cost,

application of heat this soluble sulphate, in common with all organic salts, is decomposed, yielding a carbonaceous residue. Could Dr. Nevins have shown that which is opposed to all experimental results with organic compounds, that in the presence of sulphuric acid, quinine is not readily carbonized, and the reverse of this is the fact, as may readily be ascertained by heating a crystal of the soluble sulphate, by the side of a sample of quinine purposely adulterated with sugar or gum, his test might be so far admissible; but as Dr. Nevins has not shown this, and it cannot be shown withal, therefore his test is fallacious.

36, Paternoster Row.

[We cannot coincide in opinion with Mr. Mowbray in his unqualified condemnation of Dr. Nevins's test. In our last number a precaution was pointed out by Dr. Nevins himself, an attention to which would, we think, obviate the chief source of fallacy. Mr. Mowbray states that, on the application of heat to the solution of disulphate of quinine in oil of vitriol, "the soluble sulphate in common with all organic salts, is decomposed, yielding a carbonaceous residue." This is an error: disulphate of quinine forms an exception to the general rule, and may be boiled in strong oil of vitriol without becoming blackened. Upon this fact is founded the test recommended by Dr. Nevins. It is true that if the salt becomes dry round the edges of the boiling liquid, it will cease to be protected by the oil of vitriol, and will become charred like other organic substances, as Dr. Nevins has stated.

We think a modification of the test might be adopted with advantage, which consists in dropping the disulphate to be tested into cold oil of vitriol undiluted. If pure, no change of colour is produced. If sugar be present a blackness will gradually ensue. Salicine under similar circumstances produces a bright red colour. By previously moistening the salt with a drop or two of water, the action of the test is more speedy. Mr. Mowbray is in error in stating, that if the oil of vitriol be added undiluted to the disulphate the salt will not be dissolved by the subsequent addition of water.-ED.]

ON THE EXISTENCE OF PHOSPHORIC ACID IN ROCKS OF IGNEOUS ORIGIN.

BY GEORGE FOWNES, PH. D.

THE important although obscure functions attributed to the elementary body phosphorus, both in the vegetable and in the animal kingdoms, and the well-known fact that rocks of nearly every description afford on disintegration soils more or less capable of supporting the life of plants, and from which consequently phosphoric acid cannot possibly be absent, seemed to render a search for that substance in rocks of igneous origin generally very desirable, because if there found, an easy and satisfactory explanation of the origin and first source of the element in question would be given. As I am

not aware that any direct researches on this subject have yet been made, or at least placed on record, I venture to submit to the notice of the Royal Society the results of a few experiments made by myself, which, so far as they go, resolve the question in the affirmative.

The first substance tried was the fine white porcelain-clay of Dartmoor, Devon, the result of the disintegration of the felspar of the granite of that district. This is one of the chief components of porcelain and of the finer kinds of English earthenware, and was found on analysis to correspond very closely in composition with that of the material employed in the manufacture of the Sèvres porcelain. It was thought that phosphoric acid, if present, would be in combination with a portion of the alumina and as the phosphate of that earth is readily soluble in dilute mineral acids, while the silicate offers great resistance to these agents, mere digestion with acid would suffice to extract the whole, or the greater part of the phosphate, which could be afterwards precipitated by an alkali, and examined.

With this view, 1000 grains of the clay were boiled during several hours in a flask with a quantity of pure dilute hydrochloric acid; a large bulk of distilled water was then added, and the whole allowed to rest until perfectly clear. The acid liquid was then carefully decanted from the undissolved clay, evaporated in a porcelain basin to a small bulk, and precipitated by a slight excess of pure ammonia. The scanty, reddish precipitate obtained, which consisted chiefly of alumina and oxide of iron, was collected upon a little filter, thoroughly washed with distilled water, dried, and ignited. It was next reduced to fine powder, and mixed with an equal weight of pure silica in a finely divided state, and six times as much anhydrous carbonate of soda. This mixture was heated to fusion in a platinum crucible. When cold, the melted mass was acted upon by boiling water, and the soluble and highly alkaline portion separated by a filter from the insoluble silicate of alumina. The solution was mixed with excess of nitric acid, evaporated to dryness, water added, and the product filtered. The liquid thus obtained was divided into two portions; one of these was carefully neutralised by a little ammonia, and mixed with a few drops of solution of nitrate of silver; a distinct yellow precipitate appeared, which was freely soluble in dilute nitric and in acetic acids. The second portion was mixed with excess of ammonia and some hydrochlorate of ammonia, and a few drops of solution of sulphate of magnesia added. After a short interval, a crystalline, granular, white precipitate, the ammonio-magnesian phosphate made its appearance, which increased in quantity by agitation.

This experiment, which demonstrates the presence of a small quantity of phosphoric acid in the clay, in a most unequivocal manner, was several times repeated with a like result. The purity of the acids, carbonate of soda, and other materials employed, were rigorously tested, and filtration through paper of the original acid liquid purposely avoided, lest a trace of earthy phosphate should have been dissolved from the paper.

The porcelain-clay is extracted from the disintegrated granite by mere washing with water, and subsidence, and the water of the district in which it is found is, in all probability, exceedingly pure. It was thought worth while, however, to examine in the same manner the decomposed rock, which had not been subjected to any artificial treatment, and a specimen taken by myself from the quarry was chosen for the purpose. The result showed the presence of phosphoric acid as in the clay, and apparently to about the same extent, allowance being made for the quartz-grains, mica, &c.

In the examination of unaltered felspar, I failed, unfortunately, in getting a conclusive result. The mineral, although reduced to very fine powder by trituration in a mortar of Swedish porphyry, was found to be so hard and dense as to resist completely the action of the acid at a boiling temperature. An insignificant quantity of oxide of iron was dissolved out, in which no phosphoric acid could be detected. 200 grains of the powdered felspar were

then fused with a large excess of carbonate of soda: the mass was treated with water, filtered, the solution supersaturated with nitric acid, and evaporated to dryness; water was poured upon the residue, and the whole placed upon a filter. The solution was then examined, as before, for phosphoric acid, but with an indistinct and doubtful result. Too small a quantity of the felspar had been used, and the mass of nitrate of soda present interfered too seriously with the action of the tests to render their evidence of any value. A far better mode of investigation would be, to act upon the powdered mineral with hydrofluoric acid, in the manner recommended by some analysts in the examination of natural silicates containing an alkali; not being, however, in possession of the necessary platinum vessels, I was obliged to abandon the attempt.

Other substances were then tried with very decisive results. The method of proceeding adopted was very much the same as that already described. The minerals were very finely powdered in the porphyry mortar and boiled, as before, with dilute hydrochloric acid. All were much more readily attacked than the porcelain-clay, and yielded solutions containing a large quantity of alumina and oxide of iron. The liquid was separated from the insoluble part by decantation, evaporated nearly to dryness, water added, and then an excess of ammonia. The copious, bulky precipitates obtained were washed and digested in dilute acetic acid, which has the property of dissolving with great facility both oxide of iron and alumina, while it leaves untouched the phosphates of those bases. The undissolved residue was dried, ignited, fused with silica and carbonate of soda, and the product examined in the manner already described. The addition of silica is indispensable to the retention of the whole of the alumina in an insoluble condition. Phosphate of alumina is not decomposed by carbonate of soda by fusion, or only partially, and is besides soluble in an aqueous solution of that salt.

The results of the examination may be thus briefly stated :—

Dark gray vesicular lava from the Rhine, used at Cologne as a building-stone, being exceedingly strong and durable.-Enough phosphate of soda was extracted from 1000 grains of this substance to exhibit the yellow phosphate of silver, and the phosphate of magnesia and ammonia upon a large scale. The phosphoric acid might be said to be here very abundant, that is, comparatively speaking. No attempt was however made to estimate it quantitatively, as the operation is attended with great difficulty, and the result of doubtful value from the unavoidable errors of experiment bearing too large a proportion to the quantity of the substance.

White trachyte of the Drachenfels, near Bonn, on the Rhine.—This rock is apparently as rich in phosphoric acid as the preceding; nothing could be more distinct and satisfactory than the indications of the reagents.

Dark red, spongy, scoriaceous lava from Vesuvius.-This was tried in the same manner, and yielded abundance of phosphoric acid.

Compact, dark green basalt, or toadstone, from Cavedale, Derbyshire.-This substance was very tough, and difficult to powder. Enough phosphate of soda was, however, extracted from 750 grains of the rock to exhibit very unequivocally the characteristic tests described.

Dark blackish-green, extremely strong basalt from the neighbourhood of Dudley, termed Rowley-ragg, gave a very similar result. Phosphoric acid is not so plentiful in these substances as in the lava, although its presence is easily rendered evident.

An ancient porphyritic lava containing numerous crystals of hornblende, from Vesuvius.-The phosphoric acid was here very distinct, but not so abundant as in the more recent lava.

A specimen of tufa, or volcanic mud, also from Vesuvius, was found to contain phosphoric acid in notable quantity.

These were all the substances tried they were taken, as is at once seen,