Some of a peculiar appear ance noticed. These have been seen only in the clear in tervals of milar to these are those which are common in clear frosty winter nights. Larger ones than these generally attend warm summer evenings, particularly when cirro-cumulus and thunder clouds abound*, with easterly winds. On the 10th of last month, a showery day with northerly wind was followed by a very clear night abounding with small meteors, but they were of a very peculiar and unusual kind, being of a blueish white colour, like the burning of phosphorus, and they left long trains behind them, of the same colour, which lasted for two or three seconds after their extinction. I suppose in the space of an hour I saw above thirty of them, but they were all of this kind, and left the long white tails, which remained for some seconds in the tract in which the stars had gone. These kind of meteors are strikingly different from the common kind noticed above; I have sometimes seen them before, but it has always been in the clear intervals of showery ther, followed weather, previous to the occurrence of high wind: it was by high winds, probably this sort of meteor to which Virgil alluded as a Alluded to by prognostic of windy weather. showery wea Vigil. A stationary meteor. Sæpè etiam stellas, vento impendente, videbis On the evening of the 25th of last June I saw a meteor, which was a pèrfectly stationary accension, and lasted scarcely a second; it was followed by many days of damp rainy weather. I wish that Meteorologists would note down the peculiarities observable in meteors in their monthly journals. I shall conclude by observing, that, if these considerations should appear trifling and frivolous to any of your readers, it must be remembered, that it is only by accurate and repeated observation of a multitude of phenomena, that the science of meteorology can be brought to any degree of perfection. Clapton, Sept. the 18th, 1811. I remain, Sir, yours &c. THOMAS FORSTER. I do not allude to those very large meteors, which occasionally appear: Such for example, as that seen in August, 1783. XI. On the Composition of Zeolite. By JAMES SMITHSON, Esq. ascertained MINERAL bodies being, in fact, native chemical pre- Species of m parations, perfectly analogous to those of the laboratory of nerals can be art, it is only by chemical means, that their species can be only by cheascertained with any degree of certainty, especially under mistry. all the variations of mechanical state and intimate admixture with each other, to which they are subject. And accordingly, we see those methods, which profess to supersede the necessity of chemistry in mineralogy, and to decide upon the species of it by other means than hers, yet bring an unavoidable tribute of hoinage to her superior powers, by turning to her for a solution of the difficulties, which continually arise to them; and to obtain firm grounds to relinquish or adopt the conclusions, to which the principles they employ lead them. Zeolite and natrolite have been universally admitted to be Zeolite and natrolite sup species distinct from each other, from Mr. Klaproth having posed to be disdiscovered a considerable quantity of soda and no lime, in tinct species. the composition of the latter, while Mr. Vauquelin had not found any portion of either of the fixed alkalis, but a considerable one of lime, in his analysis of zeolitet. The natrolite has been lately met with under a regular crystalline form, and this form appears to be perfectly similar to that of zeolite; but Mr. Haüy has not judged himself warranted by this circumstance, to consider these two bodies as of the same species, because zeolite, he says, "does not contain an atom of soda‡." I had many years ago found soda in what I considered to Soda found in be zeolites, which I had collected in the island of Staffa, lites long ago; supposed zeohaving formed Glauber's salt by treating them with sulphuric acid; and I have since repeatedly ascertained the presence of the same principle in similar stones from various Phil. Trans. for 1811, p. 171. +Journal des Mines, No. XLIV. other but their identity with Haüy's meso. other places; and Dr. Hutton and Dr. Kennedy had likewise detected soda in bodies, to which they gave the name of zeolite. There was, however, no certainty, that the subjects of any of these experiments were of the same nature as what Mr. type not ascer- Vauquelin had examined, were of that species which Mr. tained. Hauy calls mesotype. A specimen. sent by Mr. Haüy. This zeolite, or mesotype, analysed. Mr. Haüy was so obliging as to send me lately some specimens of minerals. There happened to be among them a cluster, of zeolite in rectangular tetrahedral prisms, terminated by obtuse tetrahedral pyramids, the faces of which coincided with those of the prism. These crystals were of a considerable size, and perfectly homogeneous, and labelled by himself" Mesotype pyramidée du depart. du Puy de Döme." I availed myself of this very favourable opportunity, to ascertain whether the mesotype of Mr. Haüy-and natrolite did or did not differ in their composition, and the results of the experiments have been entirely unfavourable to their separation, as the following account of them wiil show. 10 grains of this zeolite being kept red hot for five minutes lost 0.75 of a grain, and became opaque and friable. In a second experiment, 10 grains, being exposed for 10 mi-nutes to a stronger fire, lost 0.95 of a grain, and consolidated into a hard transparent state, 10 grams of this zeolite, which had not been heated, were reduced to a fine powder, and diluted muriatic acid poured upon it. On standing some hours, without any application of heat, the zeolite entirely dissolved, and some hours after, the solution became a jelly: this jelly was evaporated to a dry state, and then made red hot. Water was repeatedly poured on this ignited matter, till nothing more could be extracted from it. This solution was gently evaporated to a dry state, and this residuum made slightly red hot. It then weighed 3.15 grains. It was muriate of soda. The solution of this muriate of soda, being tried with solutions of carbonate of ammonia and oxalic acid, did not afford the least precipitate, which would have happened had had the zeolite, contained any lime, as the muriate of lime* would not have been decomposed by the ignition. The remaining matter, from which this muriate of soda had been extracted, was repeatedly digested with marine acid, till all that was soluble was dissolved. What remained was silica, and, after being made red hot, weighed 49 grains. The muriatic solution, which had been decanted off from the silica, was exhaled to a dry state, and the matter left made red hot. It was alumina. To discover whether any magnesia was contained among this alumina, it was dissolved in sulphuric acid, the solution evaporated to a dry state, and ignited. Water did extract some saline matter from this ignited alumina, but it had not at all the appearance of sulphate of magnesia, and proved to be some sulphate of alumina, which had escaped decomposition, for on an addition of sulphate of ammonia to it, it produced crystals of compound sulphate of alumina and ammonia, in regular octahedrons. This alum and alumina were again mixed and digested in ammonia, and the whole dried and made red hot. The alumina left weighed 3.1 grains. Being suspected to contain still some sulphuric acid, this alumina was dissolved in nitric acid, and an excess of acetate of barytes added. A precipitate of sulphate of barytes fell, which after being edulcorated and made red hot, weighed 1-2 grains. If we admit of sulphate of barytes to be sulphuric acid, the quantity of the alumina will be = 3·1 — 0·4 = 2·7 grains. 1 ་་་ From the experiments of Dr. Marcett, it appears, that 3.15 grains of muriate of soda afford 1.7 grain of soda. Hence, according to the foregoing experiments, the 10 Its component grains of zeolite analysed consisted of parts. These names are retained for the present, as being familiar, though since Mr. Davy's important discovery of the nature of what was called -'oximuriatic acid, the substances, to which they are applied, are known not to be salts, but metallic compounds analogous to oxides. 1 ♦ Phil, Trans. 1807: or Journal, vol. XX, p. 39. Reasons for retaining the name of zeolite. As these experiments had been undertaken more for the purpose of ascertaining the nature of the component parts of this zeolite than their proportions, the object of theth was 'considered as accomplished, although perfect accuracy in the latter respect had not been attained, and which, indeed, the analysis we possess of natrolite by the illustrious chemist of Berlin renders unnecessary. I am induced to prefer the name of zeolite for this species of stone, to any other name, from an unwillingness to obliterate entirely from the nomenclature of mineralogy, while arbitrary names are retained in it, all trace of one of the discoveries of the greatest mineralogist who has yet appeared; and which, at the time it was made, was considered as, and was, a very considerable one, being the first addition of an earthy species, made by scientific means, to those established immemorially by miners and lapidaries, and hence having, with tungsten and nickel, led the way to the great and brilliant extension, which mineralogy has since received. And, of the several substances, which, from the state of science in his time, certain common qualities induced Baron Cronstedt to associate together under the name of zeolite; it is this which has been most immediately understood as such, and the qualities of which have been assumed as the characteristic ones of the species. Names given Indeed, I think, that the name imposed on a substance by discoverers should not be by the discoverer of it ought to be held in some degree sacred, and not altered without the most urgent necessity for doing it. It is but a feeble and just retribution of respect for the service, which he has rendered to science. altered. Existence of *phosphoric found. Professor Struve, of Lausanne, whose skill in mineralogy is well known, having mentioned to me, in one of his letters, acid suspected in it, but none that, from some experiments of his own, he was led to suspect the existence of phosphoric acid in several stones, and particularly in the zeolite of Auvergne, I have directed my inquiries to this point, but have not found the phosphoric, or any other acknowledged mineral acid, in this zeolite. Js quartz an acid? Many persons, from experiencing much difficulty in comprehending the combination together of the earths, have been led to suppose the existence of undiscovered acids in stony crystals. If quartz be itself considered as an |
