1

In the fecond part, this author examines the obfervations relative to the irregularities in the increafe and decrease of luftre of the above-mentioned ftar. He alfo points out the refults which seem to arife from the obfervations and attempts to explain them. These hypothetical inveftigations are illuftrated by diagrams on two adjoining plates. Upon the whole, Mr. P. feems to confider it as poffible, that the above-mentioned ftar is of the nature of our fun, according to Dr. Herfchel's laft hypothefis concerning that luminary, which is defcribed at large in a former volume of the Philofophical Tranfactions.

VII. An Account of fome analytical Experiments on a mineral Production from Devonshire, confifting principally of Alumine and Water. By Humphry Davy, Efq. F.R.S. &c.

This mineral was found filling fome of the cavities and veins in a rock of foft argillaceous fhift near Barnstaple. Its external characters are defcribed by Mr. Davy in the following manner.

"The most common appearance of the foffil is in fmall hemifpherical groups of cryftals, compofed of a number of filaments radiating from a common centre, and inferted on the furface of the fhift; but in fome inftances it exifts as a collection of irregularly difpofed prifms forming fmall veins in the ftone: as yet, I be lieve, no infulated or diftinct cryftal has been found. Its colour is white, in a few cafes with a tinge of gray or of green, and in fome pieces (apparently beginning to decompofe) of yellow. Its luftre is filky; fome of the fpecimens poffefs femi-transparency, but in general it is nearly opaque. Its texture is loose, but its fmall fragments poffefs great hardness, so as to fcratch agate.

"It produces no effect on the fmell when breathed upon, has no tafte, does not become electrical or phofphorefcent by heat or friction, and does not adhere to the tongue till after it has been ftrongly ignited. It does not decrepitate before the flame of the blow-pipe; but it lofes its hardness, and becomes quite opaque. In confequence of the minutenefs of the portions in which it is found, few of them exceeding the fize of a pea, it is very difficult to afcertain its fpecific gravity with any precifion; but from feveral trials, I am difpofed to believe, that it does not exceed 2,70, that of water being confidered as 1,00." P. 156.

By chemical analyfis it was found that 100 parts of this mineral confift of 70 of alumine, 1,4 of lime, and 26,2 of fluid; 2,4 parts of it being loft in the course of the ope

ration.

Mr. D. found that a red heat is not, but a white heat is, fufficient

fufficient to expel from it all the water capable of being vo latilized. Fifty grains of the most tranfparent part of the foffil loft 13 grains in a red heat, and 15 in a white heat, Amongst the other ingredients, a minute portion of oxide of iron, and a fimilar portion of acid, were found in it. Thefe, however, Mr. D. fuppofes to be adventitious, fo that, in his opinion, this mineral may be confidered as a compound of about 30 parts of water and 70 of alumine; in confequence of which, Mr. D. propofes to call it Hydrargillite,

VIII. Experiments on Wostz. By Mr. David Mufhet,

This Paper contains the account of an experimental exa mination of five cakes of wootz, or caft fteel from Hindoftan, undertaken by Mr. Mufhet, at the request of Sir Joseph Banks.

In the first place, Mr. M. defcribes the different appear, ances of the cakes, for they were not of the fame uniform quality. He then relates the various experiments made by forging thofe cakes, wherein he notices their various duc tility, tenacity, &c, and to this he fubjoins the following general remarks.

"The formation of wootz appears to me to be in confequence of the fufion of a peculiar ore, perhaps calcareous, or rendered highly fo by mixture of calcareous earth along with a portion of carbonaceous matter. That this is performed in a clay or other veffel or crucible, is equally prefumable, in which the separated metal is allowed to cool; hence the cryftallization that occupies the pits and cells found in and upon the under or rounded furface of the wootz cakes.

"The want of homogeneity, and of real folidity in almoft every cake of wootz, appears to me to be a direct confequence of the want of heat fufficiently powerful to effect a perfect reduction; what strengthens this fuppofition much, is that thofe cakes that are the hardeft, i. e. that contain the greateft quantity of carbonaceous matter, and of course form the most fufible fteel, are al. ways the most folid and homogeneous. On the contrary, thofe cakes, into which the cutting chiffel moft eafily finds its way, are in general cellular, replete with lamina, and abound in veins of malleable iron.

"It is probable, had the native Hindoftan the means of rendering his caft fteel as fluid as water, it would have occurred to him to have run it into moulds, and by this means have acquired an article uniform in its quality, and convenient for those purpofes to which it is applied.

"The hammering, which is evident around the feeder and upon the upper furface in general, may thus be accounted for. When

the

the cake is taken from the pot or crucible, the feeder will moft probably be flightly elevated, and the top of the cake partially covered with fmall maffes of ore and steel iron, which the paucity of the heat had left either imperfectly feparated or unfufed. These most probably, to make the product more marketable, are cut off at a fecond heating, and the whole furface hammered fmooth.

"I have obferved the fame facts and fimilar appearances in operations of a like nature, and can account fatisfactorily for it as follows.

"The first portions of metal, that are feparated in experiments of this nature, contain the largeft fhare of the whole carbon introduced into the mixture. It follows of course, that an inferior degree of heat will maintain this portion of metal in a state of fluidity, but that a much higher temperature is requifite to reduce the particles of metal, thus for a feafon robbed of their carbon, and bring them into contact with the portion first rendered fluid, to receive their proportion of the fteely principle. Where the heat is languid, the defcent of the laft portions of iron is fluggish, the mafs below begins to lofe its fluidity, while its difpofition for giving out carbon is reduced by the gradual addition of more iron. An accumulation takes place of metallic maffes of various diameters, rifing up for half an inch or more into the glass that covers the metal; thefe are neatly welded and inferted into each other, and diminish in diameter as they go up. The length, or even the existence of this feeder or excrefcence, depends upon the heat in general, and upon its temperature at different periods of the fame procefs. If there has been fufficient heat, the furface will be convex and uniformly cryftalline; but if the heat has been urged, after the feeder has been formed and an affinity established between it and the steelified mafs below, it will only partially disappear in the latter, and the head or part of the upper end of the feeder will be found fufpended in the glafs that covers the fteel.

"The fame or fimilar phenomena take place in feparating crude iron from its ores, when highly carbonated, and difficult, from an excefs of carbon, of being fufed.

"The divifion of the wootz cake by the manufacturers of Hindoftan, I apprehend is merely to facilitate its fubfequent applica tion to the purposes of the artift; it may ferve at the fame time as a teft of the quality of the fteel." P. 171.

In order to afcertain whether wootz owed its hardness to an extra quantity of carbon, Mr. M. made feveral comparative experiments with various portions of wootz, of common caft fteel, and of white crude iron.

The method he used for determining the quantities of carbon, and which he reckons the most effectual, is to obferve the quantity of lead which is reduced, from flint glafs by

each

each fpecimen of fteel or iron. The recapitulation of his experiments is as follows:

"ift cake of wootz revived of lead

,139

"It would appear to refult from these experiments, that wootz contains a greater proportion of carbonaceous matter, than the common qualities of caft fteel in this country, and that some par ticular cakes approach confiderably to the nature of cast iron. This circumftance, added to the imperfect fufion which generally occurs in the formation of wootz, appear to me to be quite fufficient to account for its refractory nature, and unhomogeneous

texture.

"Notwithstanding the many imperfections with which wootz is loaded, it certainly poffeffes the radical principles of good steel, and impreffes us with a high opinion of the ore from which it is formed.

"The poffeffion of this ore for the fabrication of steel and bar iron, might to this country be an object of the highest importance. At prefent it is a fubject of regret, that fuch a fource of wealth cannot be annexed to its capital and talent. Were fuch an event practicable, then our Eat-India Company might, in their own dominions, fupply their stores with a valuable article,. and at a much inferior price to any they fend from this country.", P. 175.

The Meteorological Journal for the year 1804, kept, as ufual, at the apartments of the Royal Society by order of the prefident and council, is at the end of this part of the Philofophical Tranfactions. It commences with January the 1ft, and ends with December the 31, 1804. It contains the obfervations taken twice in the course of each day throughout the whole year, and the particulars are registered in nine columns, the titles of which are, Six's thermometer leaft and greatest heat, Time of making the observations, Thermometer without, Thermometer within, Barometer, Hygrometer, Rain, Winds, and Weather.

From thofe obfervations, it appears that the mean height of the thermometer for the whole year is 52°. Its greatest height, viz. 81, was obferved on the 16th of September. Its leaft, viz. 19°, was obferved on the 24th of December.

The mean height of the barometer (the bafon of which is fituated 81 feet above the level of low water fpring tides at Somerfet-house) for the whole year, is 29,85 inches. The mean of the hygrometer for the whole year is 81,2. The whole quantity of rain amounts to 20,973 inches.

At the end of this journal we alfo find, what had been omitted for several years before; viz. a statement of the des clination of the magnetic needle, which at a mean is 24°. 10,7 Weft; the extremes being 24°;11′,8; and 24°,8′4.

ART. VI. Naval Chronology: or, an Hiftorical Summary of Naval and Maritime Events. From the Time of the Romans to the Treaty of Peace, 1802. With an Appendix. By Ifaac Schomberg, Efq. Captain in the Royal Navy. 5 volsa 8vo. pp. 3028, 21. 2s. Egerton. 1802:

THIS work would have received due notice a confiderable

time ago, had it not been accidentally miflaid, a circumflance, however, which the author will have no reafon to regret, as, in addition to any praise we can bestow, its importance muft appear more obvious from the ftupendous events of the laft few weeks. Every reflecting mind. after the first burft of gratitude, will be inclined to examiné by what means our navy firft obtained, and has progreffively increafed, its fuperiority, and in this inquiry we can recommend the prefent work, as affording moft fatisfactory as well as authentic documents. As it is not however, ftrictly speaking, an object of criticifm, nor from the na ture of its compofition, will admit of thofe extracts, by which, in other cafes, the reader is made acquainted with the style, genius, argument, &c. of the writers in question, we must be contented to fpecify its general contents, and bestow on the author the praife due to induftry and fidelity.

The first three volumes contain a Chronological Account of the British Navy, from the earliest times to the late Peace, including every engagement, general or partial, between fleets, or between fingle fhips, loffes of veffels by fhipwreck or accident, promotions and other rewards given to men of bravery, mutinies and courts martial, all the laws refpecting the navy, and all the revolutions or changes in the nature of its various appointments, rank of officers, progrefs of fhip-building, and, in a word, every particular in any respect connected with the hiftory and progress of

the