Imatges de pÓgina
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hour = 2.265. But our author very justly remarks, that their computed distances fall very short of the real; and they seem to have counted too few steps to form their calculation on.

Art. IX. On Infinite Series. By E. Waring, M.D.F.R.S. This article; as usual, we shall decline abridging.

Art. X. An Account of some Appearances attending the Conversion of cast into malleable Iron. In a Letter from T. Beddoes, M.D. to Sir J. Banks, Bart. P. R. S.-Dr. Beddoes appears, from his reasoning on these appearances, to have abandoned the old, almost forsaken, doctrine of Stahl *, and to have become an antiphlogistian. It is impossible to abridge the descriptions, and of course the reasoning. . The principal phänomena seem to be at a certain period of the process, the generation of an elastic fluid, and of a considerable degree of heat.

Art. XI. On the Decomposition of fixed Air. By S: Tennant, Esq. F.R.S. - Our author's method of decomposing fixed air we shall transcribe.

• It has long been known, that when phosphoric acid is combined with cálcareous earth, it cannot be decomposed by distillation with charcoal: for though vital air is more Atrongly attracted by charcoal than by phosphorus, yet in this compound it is retained by two attractions, by that which it has for phosphorus, and by that which the phosphoric acid has for lime; since the vital air cannot be disengaged unless both these attractions are overcome. As these attractions are more powerful than that which charcoal has for vital air, if phosphorus is applied to fixed air and calcareous earth, the vital air will unite with the phosphorus, and the charcoal will be obtained pure. These substances, in order to act upon each other; must be brought into contact when red-hot; and this may be easily affected in the following manner. Into a glass tube, closed at one end, and coated with sand and clay to prevent the sudden action of the heat, a little phofphorus Mould be first introduced, and afterwards fome powdered marble. The expe. timert succeeds more readily if the marble is slightly calcined, probably because that part which is reduced to lime, by immedia ately uniting with the phosphorus, detains it to act upon the fixed air in the other part. After the ingredients are introduced, the cube should be nearly, but not entirely clofed up: by which means so free a circulation of air as might infiame the phosphorus is preyented, whilst the heated air within the tube is suffered to escape. When the tube has remained red-hot for some minutes, it may be

• We perceive, in a late periodical work, the New London Medical Joure bal, of which we purpose to give sume account, that Ds. Black has joined the band of apoftates.

CRIT. REY, N, AR. (IV.) March, 1791. U taken taken from the fire, and muit be suffered to grow cold before it is broken. It will be found to contain a black powder, consisting of charcoal intermixed with a compound of lime and phosphoric acid, and of lime united with phosphorus. The lime and phos. phoric acid may be feparated by solution in an acid and by filtration, and the phosphorus by sublimation.'

The coal thus produced did not differ from the charcoal of vegetables. This double power of attraction did not change either the marine or the fluor acid.

Art. XII. Meteorological Journal, principally relating to Atmospheric Electricity; kept at Knightsbridge, from the gth of May 1789, to the 8th of May 1790. By Mr. J. Read. The journal is of the highest importance, though incapable of abridgment. The meteorological phænomena are little underItood, probably because we have not sufficiently attended to atmospheric electricity. At the same time, it must be obvi. ous, that more than one journal fould be kept to render the observations applicable. Three should undoubtedly be kept on the diferent seas that surround the island, to examine the connection of the atmospheric electricity with the tides: perhaps as many in the inland parts, and some in the neighbourhood of higher mountains. Our author's apparatus deserves imitation.

Art. XIII. Farther Experiments relating to the Decomposition of dephlogisticated and inflammable Air. By J. Priestley, LL.D. F.R.S.-Dr. Priestley hangs with the eagerness of apprehension on his old opinions; but his candour, in carefully examining the different facts, and confessing his errors, is highly singular and commendable. He finds that the acid is not really owing to the azote, but to the proportion of the pure and inflammable airs inflamed in the production. If the former is in excess, the acid appears. When there is not enough of the latter, the phlogisticated air is decomposed; when too much, some is even produced. There is flill, however, reason to suppose that the phlogisticated air is in some measure connected with the acid, from the circumstances in the first of the following paragraphs; and we shall copy the other, not only on account of the information which it contains, but to show how unwilling Dr. Priestley is to resign his former opinions.

• When I first prepared an account of my fate experiments for the Royal Society, I entertained this idea ; but I now consider it as a: least uncertain, because when I mix the two kinds of air in such proportions as to produce water, I find in the residuum much more phlogisticated air than I do when acid is produced, which af

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fords a fufpicion that, in this case, the principle of acidity goes whully into the phlogisticated air, which, as my former experie, ments Thew, actually contains it, though it is not easy to ascertain in what proportion.

• Having exploded three ounce meafures of a mixture of fame. thing more than two parts inflammable air, and one of dephlogirticated, and another equal quantity in which the initimmable air bore a less proportion to the dephlogisticated, the former of which I knew would yield water, and the latter acid, I found the refiduum of the former to be 0.57 oz. m. not affected by nitrous air, and weakly inflammable; and in order to find how much phlogisticated air it contained, I mixed different proportions of phlogisticated and inlammable air, and concluded from the manner of firing them, and this refiduum, that it could not confilt of less than one third of phlogisticated air, viz. 0.19 oz. m. But the residuum of the mixture which would have produced acid was o.62. oz. m. of the standard of 10, which I find by computation to contain not omre than 0.062 oz. m, of phlogisticated air. I repcated this experiment very many times, and never failed to bave a similar result ; so that it is very possible that the pure-water we find may be nothing more than the basis of the two kinds of air ; and the principle of acidity in the dephlogistated air, and the phlogiston in the in Rammable air, may combine to form a superfuous acid in the one case, and the phlogisticated air in the other.

• This supposition is strengthened by finding that whether the produce be acid, or pure water, the two kinds of air unite in nearly the same proportions. But since water has an affinity to almost every substance in nature, and a peculiarly strong one to the acid and alkaline principles, it may be impossible that it should be wholly free from them; and if they be in proper proportions to faturate one another, and in the same quantities, their presence may never appear.'

Thus are we approaching nearer to the confirmation of the opinion respecting the composition of water, and still nearer to the downfall of the phlogistic system. It is held up almost by Dr. Priestley alone.

Art. XIV. Experiments on Human Calculi. In a Letter from Mr. T. Lane, F.R.S. to W. Pitcairn, M. D. F. R.S -The substance of these experiments have been long before the public, and the detail is of little importance. They only fhow that calculi differ in their chemical qualities; and that volatility is connected with solubility in alkalis. Do these remarks, however, at all influence the doctrine of a peculiar acid? Why is our very able (unknown) correspondent the author of the Treatise on the Stone and Gravel,' so long filent? Art. XV. Chermes Lacca. By W. Roxburgh, M.D. of

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Samulcotta. Communicated by P. Rufel, M.D. F.R.S.Dr. Roxburgh describes these little animals very carefullyThe number of males is not more in proportion to that of females than as one to gooo. The eggs, arid glutinous liquor they are found in, is of a bright red colour; and our author thinks, if carefully preserved, would be as valuable as cochineal.

Art. XVI. The Longitudes of Dunkirk and Paris from Greenwich, deduced from the Triangular Measurement 1787, 1788, supposing the Earth to be an Elipsoid. By Mr. j Dalby; communicated by C. Blagden, M. D. Sec. R. Š.--The longitude of Dunkirk refpecting Greenwich has been hitherto computed by spherics, supposing that the surface of a sphere nearly coincides with the surface of the earth from east to weit. On an elipsoid it is about 1".5 more; on a more accurate calculation it scarcely, perhaps, reaches 1".

Art. XVII. On the Method of determining, from the real Probabiliti:s of Life, the Values of contingent Reversions in which three Lives are involved in the Survivorship. By Mr. W. Morgan, F.R.S.- This is a very correct and valuable are ticle; but it is impollible to abridge it. The calculations are accurate, and the method clear and ingenious.

Art. XVIII. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon in Rutland; by T. Barker, Esq. with the Rain in Surrey and Hampfhire, for the Year 1790. Communicated by T. White, Esq. F.R.S-The thermometer was from 85% to 251: but the former number was evidently from reflected fun, since the thermometer within doors was never above 75 in the same month. The barometer was froin 30.13 to 28.32. The rain at Lyndon 21.629 inches; at South Lambeth, 22.31; at Selbourn 32.27; at Fyfield 22.05. The winter was mild; the summer cold and fhowery; the autumn warın.--Mr. Barker adds an account of chalk found at Redlington in Rutland, and at Stukeley in Huntingdon, out of the usual direction of the chalk beds.-Buz that there have the fixed direction which he supposes, we sus. pect to be without foundation.

Art. XIX. Description of a simple Micrometer for measuring small Angles with the Telescope. By Mr. T. Cavallo, F.R.S.

The micrometer consists of a piece of mother of pearl, minutely divided, and situated in the focus of the eye-glass of a telescope. It is cafily constructed ; and its use, by means of the table subjoined, will be found very convenient.

Art. XX. A new Method of Investigating the Sums of Infinite Series. By the Rev. S. Vince, A. M. F. R. S.-An ingenious paper, incapable of being given in an abstract.

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Art. XXI. Experiments and Observations to investigate the Composition of James's Powders. By G. Pearson, M. D. F.R.S.-We have seen nothing more clear and satisfactory than the investigation before us. The peculiar preparation of antimony, fold as Dr. James' invention, is a very convenient and useful one. Our author first examines this preparation with that minute and scientific chemical acumen, that scarcely leaves room for doubt or fufpicion: nothing of the flightest practical importance seems to have remained without investigation. From 240 grains, he procured 100 of phosphorated lime; 57.15 of algaroth powder, a soluble calx of antimony; 19.85 of an insoluble antimonial calx, with a little phosphorated lime; 55 of the same caly, with a suspicion only of the mixture of lime. The deficiency amounted but to 8 grains. The following facts are curious and little known.

• The above analysis thewed no eflential ingredients of James's powder but antimonial calces, phosphoric acid, and calcareous earth, which trvo lait fubftances appeared to be united together ; but it would have been vain and unnecessary labour to have attempted to make this powder by mixtures of any of the commonly known calces of antimony and phosphorated time; because none of them, from their well known qualities, could form a powder ef the same colour and specific gravity as James's powder, and like it partially soluble in acids. From the above experiments, however, the probability was evident, that this substance might be made by calcining rogether antimony and bone-ashes ; which operation produces a pou der called Lile's and Schawanberg's feverpowder; a preparation described by Schroder and other chemists 150 years ago. The receipts for this preparation differed in the proportion of the antimony to the bone-ames, and in the state of the bone ; some directing bone-thavings to be previoudy boiled in water ; others ordered them to be burnt to ashes before calcining them with antimony; and in other prescriptions the bone-lavings were directed to be burnt with the antimony. According to the receipt in the possession of Mr. Bromfield, by which this powder was prepared forty-five years ago, and before any medicine was known by the name of James's powder, two pounds of hart's-horr shavings must be boiled to dissolve all the mucilage, and then, being dried, be calcined with one pound of crude antimony, till she smell of fulphur ceases, and a light grey powder is produced. The same prescription was given to Mr. Willis, about forty years ago, by Dr. John Eaton, of the college of physicians, with the material addition, however, of ordering the calcined mixture to be exposed to a great heat in a close vessel to render it white. Mr. Turner made this powder above thirty years ago by calcining to. gether cqaal weights of burnt hart's-horn and antimony in an open

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