its compounds present some analogy to those of the second, and still more to those of the fourth group. Solid carbonic acid, obtained by cooling the liquid, is a transparent glassy substance resembling fused boric acid. The bichloride of carbon, CC14, is comparable to the chlorides of silicon and tin, SiCl4 and SnCl4, &c. The elements fluorine, oxygen, nitrogen and carbon, which would thus stand at the head of the four groups, present a curious numerical sequence :— : It is observable that the monhydrides are powerful acids, the binhydrides somewhat neutral bodies, and the terhydrides rather alkaline than otherwise. Similar relative differences in character may be traced to a certain extent in their corresponding deri vatives. In all four groups a gradual development of metallic characters accompanies the increase in atomic weights, illustrating forcibly the extremely artificial character of the division of the elements into metallic and non-metallic bodies. In the several groups to be subsequently considered, we do not find the perfec tion of metallic character pertain to those members which have the highest atomic weights. It is interesting to observe, that by the use of more or less empirical seriated formula, and by a recognition of chloroderivatives in mineral as well as in organic chemistry, it is possible to manifest clearly the really simple relations which subsist between the members of the different groups, and to reduce to an orderly position numerous bodies generally considered anomalous; as is the case, for instance, with kakodylic and stibtriethylic compounds*. Remembering the greater development of basylous characters in arsenic and antimony than in nitrogen and phosphorus, the compounds of kakodyle and stibtriethyle are strictly comparable, not only in formulæ but in properties, to their normal azote and phosphorus congeners. * Vide Cavendish Society's translation of Laurent's 'Chemical Method,' p. 278 et seq., to learn the ingenious contrivances that were resorted to by Laurent for obviating the anomalies presented by the kakodylic and stibethylic compounds. LX. On the Connexion of Catalytic Phænomena with Allotropy. By C. S. SCHÖNBEIN. [Concluded from p. 261.] THE property of changing O into O is not, however, confined exclusively to inorganic substances; for according to my more recent experiments, a number of organic substances act the part of exciters of oxygen and carriers of O. Among these I may especially mention the camphene oils, of which oil of turpentine may be taken as the type. With reference to this oil, my experiments have shown that it takes up oxygen even in the cold, proportionally more rapidly under the influence of sunlight, and much more slowly in the dark. But this oxygen associated with the oil does not immediately produce true oxidizing actions, as is evident from the fact that it may be again transferred to a variety of inorganic and organic oxidizable substances; that is, the oil of turpentine charged with oxygen comports itself as a powerfully oxidizing agent. It separates, for instance, iodine from iodide of potassium, converts sulphurous acid instantaneously into sulphuric acid; oxidizes phosphorus first to PO3, then to POs, protosalts of iron to persalts, indigo-blue dissolved in sulphuric acid to isatine, &c.;-all of them, it will be seen, oxidizing actions perfectly similar to those which oxygen produces when it has been allotropized by electricity or phosphorus. We may therefore ascribe to oil of turpentine, as to phosphorus, binoxide of nitrogen, &c., the property of allotropizing common oxygen. And since this oil, after it has been deprived of its Ŏ by oxidizable substances, can again take up fresh oxygen, and can convert this into the Ŏ condition, we may compare it more espe cially with binoxide of nitrogen, and may consider it, like that body, as an exciter of oxygen and carrier of Ŏ. I will here take the opportunity of remarking, that I have succeeded in obtaining in the past winter an oil of turpentine which contained more than 2 per cent. of ozonized oxygen, as is evident from the fact that a gramme of it was able to decompose 220grms. of my normal tincture of indigo, which had such a standard that 10 grms. of it were decolorized by 1 milligramme of Ŏ. This oxygen does not, however, even in the cold comport itself quite indifferently towards the constituents of the oil of turpentine; it gradually oxidizes this liquid, and hence the formation of resin, water, carbonic acid, &c. This action takes place the more rapidly the higher the temperature of the oil containing Ŏ, whence it arises that oil of turpentine may be more strongly charged with Ŏ in winter than is possible during summer; although, all other circumstances, insulation, &c. being equal, the ozonization of common oxygen occurs much more rapidly when exposed to heat than in the cold, as follows from the fact that oil of turpentine quite free from O, spread out in a thin layer and exposed in summer to the air and light, dries up to resin in far shorter time than is the case under the same circumstances in winter. This formation of resin, like the oxidation of sulphurous to sulphuric acid, or of indigo-blue to isatine, is not effected by O, but by O. If the allotropy of oxygen had not been discovered, and if the allotropizing property of oil of turpentine were still unknown, the fact, that this gas, standing in contact with oil of turpentine, oxidizes a series of substances towards which it is of itself chemically indifferent, would be considered as a contact or catalytic action of the oil. We may now, however, go a step further, and may refer the oxidizing actions caused by the oil of turpentine, like so many other so-called catalytic actions, to an allotropic modification of oxygen, produced in this case by the oil of turpentine. The comportment, not only of the rest of the camphene oils and of common æther, but also of several other organic substances, is similar to that of oil of turpentine. One of the most interesting of these is contained in the juice of many mushrooms, and I showed, last year, that it takes up common oxygen even in the dark, and so changes it that it may be readily transferred to other oxidizable substances; a substance, therefore, which again is comparable to binoxide of nitrogen as an exciter of oxygen and carrier of Ŏ. Substances quite analogous, as far as this chemical action is concerned, are found in a large number of plants, and probably occur more or less extensively in all. I have found them in the most various species of plants; and I will here add, that the wide diffusion of such organic ozonizing substances may be very easily proved by means of freshly-prepared tincture of guaiacum. Every substance by which this resin-solution is turned blue has the property of transforming O into Ŏ; and everything which causes this coloration, even without the presence of O, is to be considered as a carrier of Ŏ. Indigo-blue dissolved in sulphuric acid is another very valuable means of recognizing the various conditions of oxygen, and may be applied for this purpose in many cases in which the tincture of guaiacum could not be used. Since this colouring matter can be oxidized to isatine by O, but not by O, it can be conjectured from the decolorization, or from the unchangeability of the indigo solution, whether under the given circumstances Ŏ has been changed into Ŏ or not. I have already shown, years ago, that tincture of indigo is decomposed by common oxygen, when both bodies are placed Phil. Mag. S. 4. Vol. 13. No. 88. June 1857. 2 H in contact with a number of inorganic and organic substances. Phosphorus, as need scarcely be mentioned, is especially distinguished among inorganic substances. When shaken in a finelydivided condition with atmospheric air and solution of indigo, the latter is decomposed with tolerable rapidity at ordinary temperatures, and very rapidly at a somewhat higher temperature. We are no longer surprised at this action; for we know now, that under these circumstances phosphorus ozonizes atmospheric oxygen; and the decomposition of the indigo solution can be effected even without the presence of phosphorus, that is, by first leaving atmospheric air for some time in contact with phosphorus, then removing the phosphorus, and shaking the air thus treated with the tincture of indigo. It is scarcely necessary to say that this action is produced by the oxygen allotropized by the phosphorus. Among organic substances, the camphene oils and common æther are similar in their comportment to phosphorus; with this difference, however, that these substances act less powerfully than the latter body, and that their activity is essentially increased by light, while that of phosphorus appears to be wholly independent of this agent. This chemically exciting influence is conveniently proved with water which has been coloured blue by solution of indigo, and which is brought in contact with oil of turpentine, or æther free from Ŏ. Under these circumstances the coloured water becomes decolorized, and in the light with greater rapidity than in the dark. Similar results are obtained if the diluted solution of indigo is mixed with spirit of wine, wine, beer, wood-spirit, tartaric acid, oleic acid, linseed oil, &c., and exposed to the action of air under the influence of light, from which it is clear that these substances also possess the property of inciting O to oxidize dissolved indigo to isatine, that is, of transforming it into O. That the latter substances have themselves undergone an oxidation by the oxygen which they have modified, in consequence of the oxidizablity of their constituents, is just as self-evident as that oxygen ozonized by phosphorus unites with that body to form phosphorous acid. It would therefore, I believe, be an incorrect view were we to regard the oxidation of oil of turpentine, of tartaric acid, &c., as the immediate cause of the oxidation of indigo-blue. The ozonization of common oxygen must precede both acts of oxidation, and hence these do not follow each other, but are simultaneous. I must mention here the remarkable compounds of the alcohol radicals with metallic bodies, which are distinguished by their high degree of oxidizability. Stibæthyle, cacodyle, &c. take fire even at ordinary temperatures; and they also, in contact with atmospheric air or oxygen, decompose tincture of indigo at least as rapidly as phosphorus, as I have shown on a former occasion. We may assume therefore that these compounds exercise an allotropizing influence on common oxygen, the magnitude of which may be equal to the degree of their oxidizability. The decay of organic substances in atmospheric air is certainly one of the most important and extensive oxidizing processes, and in my opinion this is effected not by common oxygen, but by Ŏ; that is, just in the same way as the so-called slow combustion of phosphorus, the change of oil of turpentine into resin, &c., of spirit of wine into acetic acid and water, &c. This view leads to the further assumption, that atmospheric O is transformed into O by the organic substances themselves, aided by the agencies of heat and light acting in the same direction. And inasmuch as we consider catalytic and allotropizing actions as the same thing, so may we view decay as the greatest catalytic process which is to be found in the economy of nature, My earlier experiments have shown, in reference to decayed wood (Scheinholz), that when left in contact with atmospheric air it slowly decomposes dilute tincture of indigo. The parings of raw potatoes and many other vegetable structures do the same, and also turn tincture of guaiacum blue, I will here again call to remembrance the fact, that a substance is contained in a great number of mushrooms, which absorbs atmospheric oxygen and changes it into the Ŏ condition; and further investigations will show that there are many other vegetable and animal substances of this kind still unknown. I have not long since shown, that this fungus substance readily gives up its oxygen to other oxidizable, and especially organic substances, for example to albumen, and produces oxidizing actions which would not take place without its intervention. Such facts appear to me to help us towards a better comprehension of the decay of organic substances, and to throw some light upon the well-known observation, that mixtures of organic substances, such as we always meet with in vegetable and animal structures, decay more easily or more rapidly than the substances contained in these mixtures when exposed in an isolated condition to the action of atmospheric oxygen. Numerous examples have shown us what a great influence the presence of certain bodies exercises upon the comportment of other substances towards oxygen. Free hydrogen, for example, remains quite indifferent towards oxygen at ordinary temperatures; but its decay, that is, its oxidation, commences as soon as we introduce platinum into the gaseous mixture. We have also seen that a great number of inorganic and organic substances which are indifferent to oxygen are oxidized in the |