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ter is confined merely by the furrounding fheath. It can scarcely have efcaped the notice of an obferver, that when a new feather first makes its appearance on the body of a bird, a tender filmy fubftance environs and defends it, during its infant state. But no fooner does the web increase to any strength, than the film gives way, and the feather continues to go to its perfect maturity.

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That this difeafe did not occafion the bird's death, I am certain; as it appeared healthy and well during the time it lived.'

Almost every article in this volume is illuftrated with a plate, and fometimes with two or three, always very clearly and correctly engraved; in one or two inftances beautifully and highly finished. On the whole, this firft volume appears a very interefting and useful one. The great object of the Society to establish and correct the immenfe fyftem of the Swedish naturalist, which, vaft in its extent, and numerous in its fubjects, cannot be accurately finifhed in every part, deferves our commendation. It is with pleasure we fee that their attention is directed alfo to the natural history of this country. For each defign, their knowledge, their abilities, and their opportunities, are well adapted. The botanical riches of this country, either in well-furnished confervatories, in vaft collections of botanical authors, and particularly of Herbaria, unrivalled by any nation, perhaps by all the nations of Europe, may thus be drawn out for the public ufe, and contribute to extend the knowledge of nature in the most pleasing of her productions. In the other kingdoms, our opportunities are not defective; and we have every reafon to believe, from this specimen, that the attention of the Society will be equally exerted.

The Tranfactions of the Royal Irish Academy, MDCCLXXXIX. 410. 11. 5s. Boards. Bonham, Dublin. 1790.

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HIS volume is, like the former, divided into three parts; comprehending articles which may be styled by the general term of scientific; thofe of polite literature, and of antiquities. We fhall, as ufual, follow them in their order.

Art. I. Experiments on the Alkaline Substances used in Bleaching, and on the Colouring Matter of Linen-Yarn. By Richard Kirwan, Efq. F. R. S. and M. R. I. A.-It is to be regretted that chemistry, in this kingdom, has not been more carefully ftudied, or applied to the different arts. It is within our own memory that the mineral acids were firft employed as fourings inftead of milk, in its acetous ftate; and we only learnt the ufe of the oxygenated muriatic acid from our neighbours. The alkaline fubftances, which are more particularly the object of our prefent author, we are generally fupplied with from

America

America or Spain. In the late war, our manufacturers were. alarmed left these fources being stopped, bleaching, as well as the glafs-houses and foap-furnaces, could be no longer fupplied, except at a great and difproportioned expence. The decompofition of falt was then thought of; and application was made to parliament to take off the duties of that falt employed in the manufacture of mineral alkali. The peace quieted the fears of the manufacturers, and no farther attempt was made. We think, however, that it ought to be refumed, and we shall felect our author's method.

I have alfo contrived another procefs for decompofing common falt. The particulars of my experiment were as follows:

ift, I rendered the common falt pure by adding to its folation a folution of mineral alkali until all the earthy matter was depofited.

zdly, To a folution of three ounces of this purified falt in nine ounces of water, I gradually added a faturate folution of 4,75 ounces of fugar of lead, both hot, until the folution of lead fcarce excited any whitenefs in that of the common falt. After one night's reft, part of the fugar of lead cryftallized in the bottom of the veffel, by which it is plain that too much of it had been used. Thefe cryftals weighed 240 grains; the supernatent liquor I again evaporated to nearly two-thirds, and after two days obtained large pellicles of acetous foda, which I separated; they weighed 325 grains; to the refiduum, which still had a fweetish Lafte, I added a folution of mineral alkali, until no farther precipitation appeared; a very fmall quantity of the alkali was fufficient for this purpose. I then evaporated the remainder nearly to drynefs; and afterwards heated it in a crucible to rednefs: in this heat it inflamed, and when calcined nearly to whiteness, I took it out and diffolved it in twelve ounces of water, filtered it, and on adding a hot folution of allum, obtained a precipitate, which when dried, weighed 169 grains, and indicated the quantity of pure alkali to be 112 grains nearly. In this process nothing is loft, for the lead may be either revived or turned into a pigment.

Laftly, Glauber's falt may afford the mineral alkali, but most eafily in the form of liver of fulphur: I endeavoured to decompose it by the above procefs, but the quantity of alkali obtained from a large quantity of it was very inconfiderable.'

We have reason to think that common falt, fuffered to deliquefce on an iron plate in a damp cellar, will have the affinity of its ingredients at leaft weakened, if the acid does not entirely unite with the iron, and leave the alkali in the form of efflorefcence on the plate. Mr. Kirwan analyfes the different afhes, &c. and finds the following results:

• Tabie

Cryftallized foda

Table of the quantity of mere alkali in one hundred avoirdupois pounds of the following fubftances by the aluminous teft:

One hundred pounds,

Sweet barilha

Mineral alkali.

20 lbs.

24

Mealy's Cunnamara kelp

3.437

Ditto defulphurated by fixed air

49457

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He next defcribes the method of preparing the afhes, and afterwards examines the nature of the colouring matter feparated from yarn. It feems to be an oily, or rather a refinous fubftance, though infoluble in effential oils. In his experiments on this fubject, he found 4.2 grains of the faline fubftance of kelp performed as much as 75 of that of Dantzic; 38 of barilla, 15 of that of Cashup; 21 of that of Clarke; and 213 of foap. The following conclufions deferve tranfcribing:

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1ft, Liver of fulphur is of all alkaline compounds the ftrongeft folvent of the colouring matter; next to this the cauftic vegetable, and after this the cauftic mineral alkali; the mild vegetable and the mild mineral alkali occupy the last place. Sulphur, it is faid, leaves a stain in linen; but if liver of fulphur be used in the beginning, that is to fay, in bleaching the yarn, the ftain will probably be removed by the purer alkalies afterwards ufed. Hence the folutions of kelp, cafhup, and markoft are advantageously ufed in the first proceffes of bleaching, for which Dantzic and fweet barilha are lefs fit; but fix tun of kelp will be necessary to produce the fame effect as one tun of cashup; yet as the former is manufactured at home it deferves the preference.

2dly, As the alkali manufactured from inland weeds is more powerful than the mineral, Mr. Clarke's is more powerful, or may be rendered fo, than any imported. It is already fufficiently cauftic, and may be converted into liver of fulphur only by adding one-twentieth of its weight of fulphur to it when boiling, and thus it is fitted for the firft proceffes of bleaching. In its primitive ftate it is fit for the fecond procefs, and by rendering it milder, which may be effected by burning half a bushel of charcoal in a pan in the fame room in which its folution ftands, it will be adapted to the laft proceffes, in which a less active alkali is required.

• 3diy,

3dly, Clarke's falt converted into liver of fulphur is preferable to kelp, because this latter, by the prefent manner of manufacturing it, holds charcoal in folution; this coaly matter it depofits on the yarn, and thus leaves a black tinge; whereas Mr. Clarke's is free from this contamination, to fay nothing of the far greater quantity of alkali it contains, infomuch that one tun of Clarke's is nearly equal to eight tun of kelp. Hence it clearly follows that the linen manufacture ftands in 'no fort of need of foreign falts or afhes for the proceffes of bleaching.'

Art. II. Letter from Richard Kirwan, Efq. F. R. S. and M. R. I. A. to the Right Honourable the Earl of Charlemont, P. R. I. A.—Mr. Kirwan faid that, in England, beds of coal lefs than two feet and a half in thickness, are judged not worth working. Mr. Mills affures him that thinner feams are worked in Cheshire, and particularly defcribes the ftrata at Blakelow, about a mile S. E. of Macclesfield.

Art. III. The Origin and Theory of the Gothic Arch. By the Rev. M. Young, D. D. F. T. C. D. and M. R. I. A. In this very able and ingenious effay, Dr. Young examines the different explanations given of the origin of the Gothic arch. Each feems to our author untenable, but he chiefly leans to wards Mr. Barry's opinion, of which we many years fince fpoke with refpect. Mr. Barry fuppofed the pointed arcle to have arifen from an accidental corruption of the rounded arch, in confequence of the variable changes which fancy or fafhion craves, joined with the different views and inclinations. of the conquerors of the western world: it certainly feems to have originated in Italy about the downfal of the Roman empire. Dr. Young appears to coincide with this idea, though he adds to it the fuperior advantages of the pointed arch. The comparison of the Gothic and Grecian arches is juft and correct; but we think the view might be fimplified in this way. The refiftance of the round arch certainly depends on the ac tion of two circular arcs, each refting at one extremity on the pier, and at the other on the key-ftone, the refiftance of either fupporting the other. In the comparifon, therefore, the queftion returns to the comparative ftrength of a circular and an eliptical arc. If this view be purfued geometrically, it will lead to the fame conclufions in a fhorter way than in Dr. Young's investigation, and include his laft theorem of the fuperiority of eliptical arches. The difficulty of raifing confider able weights on pointed arches will be equally apparent, as it acts to fo great a difadvantage if the arch is pointed very much, and fo partially, unlefs the refiflance at the fides is very great. Art. IV. An Account of a Difeafe which, until lately, proved fatal to a great number of Infants in the Lying-in Hofpital of

Dublin,

Dublin, with Obfervations on its Caufes and Prevention. By Jofeph Clarke, M. D. Mafter of the Hofpital above-mentioned, and M. R. I. A.-The disease which has been fo fatal to children; and in the Dublin hofpital for many years carried off nearly 16 or 17 in 100, is convulfive. The nurfes call it the nine-day fits, from the period of attack; and divide it into dif ferent fpecies according to the appearance. This mortality was fo furprising and confiderable, that it induced our author to compare the circumftances in other hofpitals with those of Dublin: the facts we shall transcribe!

That in an old hofpital, which preceded the prefent, but inftia tuted by, and under the care of, the fame gentleman, and in a less airy part of Dublin, of three thousand feven hundred and forty-fix children therein born, only two hundred and forty-one died within the first month, which are in the proportion of one to fifteen and a half, or from fix to feven in the hundred.

That during a period of five or fix years in the British Lyingin Hofpital, London, of three thousand fix hundred and eleven therein born, only one hundred and forty-fix died within the first three weeks or month, which are as one to twenty five, or four in the hundred.

That in the London Lying-in Hospital I was pofitively affured the death of an infant was a rare occurrence. It is there computed with fome confidence (for I was told that no written account is kept) that the number of ftill-born infants far exceeds the number of those dying after birth. The proportion of ftill-born we know to be about a twentieth part, or five in the hundred.

That near forty years ago, when the diseases of children were lefs understood, and more efpecially the falutary practice of inoculation, Dr. Short computed, from fome very extenfive registers, that London loft thirty-nine per cent. under the age of two yearsEdinburgh and Northampton thirty-four or thirty-five-Sheffield twenty-eight-country places from twenty to twenty-eight ;whereas in the Dublin hofpital there was loft a number equal to half of that loft in many of these places, and nearly equal to the whole of that in fome of them, in two weeks, or in about the fiftieth part of the fame space of time. From which, and fome other confiderations of lefs weight, I thought the uncommon mortality of children in the Dublin Lying-in Hofpital fatisfactorily proved.

The caufe feemed to be too great clofenefs of the wards, which brought on a difeafe that has appeared in the different forms of a convulfive or a fpafmodic diforder, affecting the jaw more partially, or the whole fyftem more generally, in many parts of the world, and been described by various practitioners. The mortality of the women is not greater in the Dublin HofCRIT. REV. N. AR. (IV.) Jan. 1792. C pital

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