but when it is deposited from animal fluids the form of the crystals is often much modified." The same authority says that pure uric acid is a white crystalline powder, requiring 10,000 parts of cold water for its solution." This being the case would account for no harm being done to my crystals by immersing them in drops of fresh water. The urates, although sparingly soluble, are much more so than uric acid. Urate of potash (neutral) is soluble, according to Miller, in forty-four parts of cold water; the urate of soda is somewhat less soluble, and the urate of ammonia is soluble in 1800 parts of cold water. The Micrographic Dictionary gives drawings of crystals of urates, none of which correspond-as some of its representations of uric acid do-with those in the Artemia, but it adds that their forms "are not very characteristic." In the article Uric Acid, in the same work, it is observed that "the crystals forming a natural deposit are almost invariably coloured, from combining with the colouring matter of the urine." Little crustaceans like brine shrimps would not be expected to colour this substance, and in all my specimens it was pure white, like glass. I should recommend anybody looking for these crystals to cut off the abdominal segments before using any compression. If the entire animal is compressed, too much mess is made to see them clearly, and unless the abdomens are placed in clean fresh water, the observer is pretty sure to be troubled by the deposit of salt from the strong brine in which the creatures dwell. THE COLUMNAR BASALT OF POUK HILL, BY J. JONES, Secretary of the Dudley and Midland Geological Society. We are so accustomed to regard the Giant's Causeway, and Fingal's Cave in Staffa, as the only British examples of columnar basalt, that perhaps the title of this chapter may appear indicative of some new discovery. This is not the case, however, for the peculiar columnar structure of the igneous rocks which occur in connection with the coal-measures of South Staffordshire, and also of the Clee Hills farther west, has been long known and recorded; but the face of basalt, which is now exposed at the extensive quarries of Pouk Hill, near Walsall, affords, perhaps, a finer section of this remark The hill able structure than has ever been exhibited before. is situated near the high road from Walsall to Willenhall, and about two miles from the former town. The basalt at this place seems to have been originally protruded from the neighbourhood of the Rowley Hills, about six miles distant, perhaps shortly after the formation of the lower coal-measures, for in an open working of the bottom-coal, to the south of the quarry, the basalt is seen reposing on the coal itself, which has been changed by contact into anthracite. In another section, exposed by cutting a tramway from the quarry, coal shales are seen to rest on the igneous rock, but they have not undergone any change; hence it is tolerably certain that the protrusion of the basalt took place immediately after the formation of the Bottom coal of the district. Mining operations have recently been carried on completely under the knoll of basalt, and no trace of any pipe or vent through which the stream of molten matter could flow has been discovered. Hence it is now generally admitted that the stream must have had its origin farther to the west, and after passing through the lower coal-measures some distance, it found an opening, and thus formed a large mound of igneous matter. The composition and mineral characteristics of this basalt are the same as that of the more remarkable localities in Scotland and Ireland. The central part of the mound has been long worked away; but, from the general arrangement of the columns, and the way in which they curve towards a point which would be directly over the middle of the quarry, there is reason to believe that the columns radiated regularly from the cooling surface of the basalt, and in the interior of the boss, assumed a vertical position. The workings on the north-eastern side show these vertical columns for a space of about thirty yards, and many of them are upwards of twenty feet in height. They are of a rude pentagonal form, and in some cases above two feet in diameter. Towards the top of the section the columns are smaller, and bend over with great regularity. A few months ago the Midland Geological and Scientific Society held one of their usual field meetings at the quarry, and examined carefully the geological features of the locality. The material is extensively used for road-making and paving in the neighbourhood. At the works of Messrs. Chance, glass makers, near Birmingham, this basalt has been melted and cast into candlesticks, vases, and other articles, which take a tolerably high polish, and somewhat resemble in appearance the black Derbyshire marbles. The mass of basalt at the Rowley Hills has also been extensively quarried for road purposes, and the largest excavation shows a very rude columnar arrangement of the igneous rock, but not nearly so well defined as that of Pouk Hill. Of course, we are not maintaining that the regular and beautiful appearance of the Isle of Staffa, or the north of Antrim, is reproduced in South Staffordshire; but the approach is so near in the case of Pouk Hill that it seems worthy of more than mere local record. A few years hence, and the quarry will doubtless be worked out; and indeed we very much question if a section equal to the one recently exposed will again be witnessed, as the basalt is being rapidly exhausted, and hardly a day passes without some of the columns being demolished. PASTEUR'S RESEARCHES ON PUTREFACTION. THE following paper was read before the French Academy on the 29th June, and will be found in the Comptes Rendus for that date:— "In every case in which animal or vegetable matter undergoes spontaneous alteration and develops fetid gases, putrefaction is said to occur. We shall perceive in the course of our examination that this definition has two opposite defects. It is too general, because it brings together phenomena that are essentially distinct; and it is too restricted, because it separates others which have the same nature and origin. "The interest and utility of an exact study of putrefaction has never been misunderstood. Long ago it was hoped it might lead to practical consequences in the treatment of maladies which the old physicians termed putrid. Such was the idea that guided the celebrated English physician Pringle when he published, in the middle of the last century, his experiments on matters septic and antiseptic, with a view to illustrate his observations on the diseases of armies. "Unfortunately the disgust inseparable from labours of this kind, joined to their evident complication, has hitherto arrested the majority of experimenters, so that nearly everything has still to be done. My researches on fermentation have naturally conducted me towards this study. The most general deduction from my experiments being that putrefaction is determined by organic ferments of the genus Vibrio. Ehrenberg has described six species of vibrio, to which he gives the following names 1. Vibrio lineola. 3. Vibrio subtilis. 4. Vibrio rugula. 5. Vibrio prolifer. "These six species, in part recognized by the first micrographers in the last centuries, have been since seen by all who have paid attention to infusoria. I reserve, so far as it concerns me, the question of the identity or the difference of these species, and of the variety of their forms, subordinated to changes in the condition of the medium in which they live. I accept them provisionally such as they are described, and I arrive at the conclusion that these six species of vibrions are six species of animal ferments, and that they are the ferments of putrefaction. Besides this, I have shown that all these vibrions can exist without free oxygen, and that they perish in contact with this gas, if nothing preserves them from its direct action. The fact that I announced to the Academy two years ago, and of which I have recently pointed out a second example, namely, that there exist animalcule ferments of the genus Vibrio which can live without free oxygen, was only a particular incident appertaining to a mode of fermentation which is perhaps the most wide-spread in nature. "The conditions under which putrefaction is manifested may vary considerably. Suppose, in the first instance, the case of a liquid, that is to say of a putrescible substance, of which all the parts have been exposed to contact with the air. Either this liquid may be shut up in a close vessel, or it may be placed in an open vessel, having an aperture more or less large. I will examine in succession what happens in the two cases. "It is commonly known that putrefaction takes a certain time to manifest itself, and that this time varies according to temperature, neutrality, acidity, or alkalinity of the liquid. Under the most favourable circumstances a minimum of about twenty-four hours is necessary before the phenomenon begins to be manifested by external signs. During this first period the liquid is agitated by an internal movement, the effect of which is to deprive of its oxygen the air which is in solution, and to replace it by carbonic acid gas. The total disappearance of the oxygen when the liquid is neutral or slightly alkaline is due, in general, to the development of the smallest of the infusoria, the Monas crepusculum and Bacterium termo. A very slight agitation occurs as these little beings travel in all directions. When this first action of exhausting the oxygen in solution is accomplished, they perish and fall to the bottom of the vessel like a precipitate; and if by chance the liquid contains no fecund germs of the ferments I have spoken of, it remains indefinitely in this condition without putrefactionwithout fermenting in any way. This is rare, but I have met with several examples. Most frequently when the oxygen in solution has disappeared, the vibrion ferments, which have no need of this gas, begin to appear, and putrefaction immediately sets in. Gradually it accelerates itself, following the progressive march of the development of the vibrions. The putridity VOL. IV.-NO. II. I becomes so intense that the microscopic examination of a single drop is very unpleasant. The fetid odour depends chiefly on the proportion of sulphur the substance contains. The odour is scarcely sensible if the matter is not sulphuretted, as, for example, in the fermentation of the albumenoid matter which water can carry away from the yeast of beer. The same is the case with butyric fermentation; and after my experiments butyric fermentation must, from the nature of its ferment, be considered as a phenomenon of exactly the same order as putrefaction properly so called. Thus we see what happens when putrefaction is in some sort restrained." "It results from what precedes, that contact with air is not necessary to the development of putrefaction, but that, on the contrary, if the oxygen, dissolved in a putrescible liquid, is not removed by the action of special beings, putrefaction will not occur, as the oxygen would cause the vibrions to perish if they tried to develope themselves." "I shall now examine the case of free putrefaction in contact with air. That which I have already said might make it appear that it could not take place under such circumstances, as oxygen kills the vibrions which excite it. Notwithstanding this, I shall demonstrate that putrefaction in contact with air is more complete than when it is effected under shelter from air." "Let us go back to our aerated liquid, this time exposed to contact with air in a wide-mouthed vessel. The removal of the oxygen takes place as previously described. The difference is that the bacteriums, etc., do not perish, but propagate themselves to infinitude at the surface of the liquid which is in contact with the air. They form a thin pellicle, which gradually thickens, falls into rags to the bottom of the vessel, is formed again, and so forth. This pellicle, with which is usually associated divers mucors and mucedines, prevents the solution of oxygen gas in the liquid, and thus permits the development of the vibrio-ferments. For them the vessel is as if closed against the introduction of air. They can even multiply in the pellicle at the surface, because they find themselves protected by the bacteriums and mucors against too direct an action of the atmospheric air." "The putrescible liquid thus becomes the seat of two kinds of action, very distinct, and which are in relation to the physiological functions of the two kinds of beings that nourish themselves in it. The vibrions, on one hand, living without the aid of atmospheric oxygen, determine, in the interior of the liquid, acts of fermentation-that is to say, they transform nitrogenous substances into more simple, though still complex, products. The bacteriums or the mucors burn these same products, and |