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cate great strength, but add considerably to the contain a known quantity; Q, cock for a dousymmetry of the horse, when viewed from be- ble current of air; R, bladder to contain the hind. A horse well formed in the gaskins, is gass; S, cock; T, cock for a double current seldom badly shaped in the fore quarters ; nor of air; 'U, glass pipe, coming from the cock are such, in general, horses of inferior action ; T to K; Z, index of ihe second current of air. exclusive of which, they are necessarily free To know the quantity of gass which any gasfrom the very awkward defect of cutting: an seous water contains, we thus dispose the appainconvenience of no small magnitude to a tra- ratus. Having shut the cock H, we fill'ihe velier with a weary horse upon a long journey. cylinder with mercury; we shut the cocks B

GASCONADE, a boast or vaunt of sonic. and K, and open the cock A, to know the thing very improbable. The term has its rise state of the apparatus; if it be in proper order, froin the people of Gascony in France. See it will not make a vacuum in the cylinder C, GASCONY.

further than the first mark; we fill the maGASCONY, a late province of France, trass up to the neck with the water we intend bounded on the W. by the bay of Biscay, on to analyse, and carefully fit the matrass to the the N. by Guienne, on the E. by Languedoc, cock K, by a screw provided with a little shield and on the S. by the Pyrenees. 'The character of leather : the whole being well secured, we of the inhabitants has been long that of a live- open the cocks K and H, and heat the water ly people, famous for boasting of their valour, to the boiling point. (Med. and Phys. Jourwhich has occasioned the name of gasconade nal. English Encyclopedia). to be given to all bragging stories. This pro- To GASP. v. n. (from gape, Skinner.) 1. vince, with Armagnac, now forms the depart. To open the mouth wide; to catch breath with ment of Gers.

labour (Addison). 2. To emit breath by openTo GASH. v. Q. (from hacher, French, to ing the mouth convulsively (Dryden). 3. To cut.) To cut deep so as to make a gaping long for (Spectator). wound.

GASP.s.

s. (from the verb.) 1. The act of openGash. s. (from the verb.) 1. A deep and ing the mouth to catch breath. 2. The short wide wound (Spenser). 2. The mark of a catch of breath in the last agonies (Addison). wound (Arbuthnot).

GASS. (from the German, gheist; or the GASHED LEAF. In botany. Folium common Teutonic gast; from which root we obincisum dissectum. Having, the sections or tain the terms ghost, ghostly, aghait.) An elastic divisions usually determinate in their number; aëriform fluid. It is written by the French, gaz or at least more so than in the laciniate leaf. but improperly: it is also written by most Eve The gashed differs from the cleft leaf (fissum), glish writers, gas, yet, we think, improperly also, ir having the sections extending but little be- as an English word, since our established orthoyond the edge (though deeper than in the cre- graphy duplicates in almost all monosyllables the nate leaf); while in the cleft leaf they reach in all, ball, call, in buff, cuff, stuff, and formerly, in

terminating consonant, as in ass, pass, lass, glass, almost to the middle. See Dissect and LA

toinn, supp, &c.: In lack, sack, crack, &c. the douCINIATE.

ble consonant is in like manner retained, the final GA'SKINS. s. Wide hose; wide breeches k, having the power of a c: while in the term gass (Shakspeare).

itself, every one spells it with a double s in the GASOLITRO, an instrument contrived by plural, and writes, not gas-es, but gass-es. M. Goldschmidt, of Paris, to examine and This term was first used in chemistry by Van measure the gasseous contents of mineral wa- Helinont, who denoted by it the vapour of charters. This apparatus was designed, not only coal, (gass sylvestre) now known to be carbonic to expedite the process, but also to get rid of acid gass: he also applied it to other aërial Auids the trouble of using lime-water to detect the produced in his experiments; as gass fingue, excarbonic acid gass, and the inaccuracy result- tricated from inflamable substances during their ing from its use, and from the variations of their analysis by heat; gass flammeum, produced pressure in the common mercurial apparatus. rit of life, &c. The air of the atmosphere he

by the deflagration of nitre; gass viliale, the spi. In Pl. LXXVIII. A is a glass funnel to pour called gass ventosum. At present, gass is emin the mercury into the glass cylinder C, which ployed as a general term, to express all those is graduated, shut by the cock B, and cement- aërial fluids, whether produced by chemical expeed on the plate D, made of delft-ware; E, riments or evolved in natural processes, which are wooden stand; F, stand to support the appa- not condensible by the cold of our atmosphere, ratus ; G, glass tube, the cavity of which is and which differ from the air of the atmosphere: about k of an inch in diameter, and which indeed, atmospheric air is a compound of three of communicates with the cylinder C; H, tube the gasses, as will appear on referring to the artiof the same diameter, communicating also cles AIR and ATMOSPHERE. The term gass does with the cylinder C, and returning by an iron not include those aërial substances which arise cock into the bottle J, intended to receive the from water, ether, and other duids, on the applimercury; K, cock for a double current of air ; cation of heat, although Lavoisier, and others, L, a matrass containing about four ounces of speak of aqueous gass, etherial gass, &c.: these water, secured to the cock by a screw; M, vapour, because they are easily condensed into

are now distinguished by the name of steam, or sandbath ; N, furnace; 0, puinp, the cylin- their respective Auids again, merely by a certain der of which is glass, secured by two screws to reduction of temperature; whereas the gasses rethe stand F; the use of this pump is to gra- tain their elasticity in every variation of the temduate the cylinder C; P, glass measure, to peraturc and pressure of the atmosphere,

of these gasses there are now a considerable the muriatic acid gass, and the sulphuric acid sumber known: the principal of them are enume- gass. rated at the end of the articles Air and CHE- He had become acquainted also, different ways, MISTRY; and will be found particularly described with that gass which shows itself in air in which under their specific names.

various bodies, and particularly coals, have been 1. History of discoveries relating to gasses. As these burnt; and on that account he had given it the aërial fluids are so curious in themselves, and of so name of coal gass; though he had seen abundance mach importance in the economy of nature, and of it in various places, and accompanying other as the knowledge of them has contributed more, phenomena, bocb in living human bodies, as for perhons, than any thing else to the advancement example in belching, and on a larger scale, as in of chemical science, we trust we shall be justified, wine and beer cellars, and during the efferves. in the opinion of our readers, for pursuing the bis- rence of different substances when acids were tory of gasses to a greater extent than is usual in poured upou them, in the Grotto del Cane and the introduction of our articles. In one sense, other subterraneous places; particularly in acid inleed, there will be an advantage in this mea- waters, from which it rises in bubbles, and they sure; for we shall thus be enabled to bring toge- are indebted to it, he says, for all their healing ther into one view a number of connected ob- qualities. He remarks also of this gass, that, as servations which must otherwise have been scat- it extinguishes the flame of a lamp or taper, it tered in different parts of our work, and which, in extinguishes also the flame of life. He proved, such a state of dispersion, would have failed to that the volume as well as the goodness of air is present a distinct and comprehensive idea of the lessened by bodies burning in it; for, having progress of discovery, relating to one of the most placed a burning taper under a glass in such a interesting branches of natural philosophy. In manner that it stood three inches above the water tracing the outlines of this history, we shall avail in the vessel, he saw the water rise, assume the ourselves of many observations in an excellent place of the decreasing air, and at length extinpaper in Tilloch's Philosophical Magazine, vol. 9. guish the taper. on the Chemical Knowledge which the Philoso- He had observed also, that an air could be prophers of the 16th and 17th Centuries had of the duced from nitre, which he called flame gass, and different Gasses.

which was disengaged on coal being added to it; If we pass over the remotest traces which occur and he thence conjectured the presence of vital here and there in the works of the ancient writers, air in that salt. He entertained also the opinion, Van Helmont seems to stand at the head of which modern chemistry has supported by so those more acute philosophers, who distinguished many conclusive proofs, that all these air-like these subtile fluids from the air of the atmosphere. Auids are indebted for their form to the effects of For, though it cannot be denied, that he disfigured fire, or, as we commonly say at present, to cahis valaable discoveries by numerous fictions, and loric. concealed them under new and commonly barba- It cannot, however, be denied, that Van Hel. rous names, which were for the most part impro- mont considered as different gasses those which pet, yet he first informed physicians and natu- differ only by accidental corruption, as the care ralists, and prored clearly by observations and bonic acid gass, according as it is drawn from this experiments, that other fluids existed, which, or that body, and in this or that manner; and though they approach very near to the air in sub- that he confounded others, or did not make a protilty, transparency, and particularly in elasticity, per distinction between them. Yet before Priestyet differ from it very much; and, as they differ ley, most of the pbilosophers who paid attention also from vapours, he distinguished them by the to this subject made no other difference between particular name of gass, as above related. He these kinds of gass, than that some of them inwas acquainted with the air of the celebrated flame when brought into contact with a burning Grotto dei Cane, near Naples, (see CARBONIC body, while others instantly extinguish a flame. ACID), as well as with the exhalations in mines, Van Helmont suspected also the great simiagainst the pernicious effects of which cautions larity which, in regard to air, is found between had been given long before his time by Andrew fame and animal life. This was more clearly Libavius and George Agricola ; and he knew also, perceived by Thomas Willis and Francis Sylvius that they killed animals which had purposely or ac- de la Boë, a man whom few have equalled in gecidentally been exposed to them, as well as impru. nius or eloquence. dent persons, and particularly miners. He was in This Sylvius proved nothing by experiments; particular acquainted with that gass which some, but he made it probable, according to his manner, because it inflames when it comes io contact with a that sourish particles of nitre floated about in the burning body, call inflammable gass, and which common atmosphere, and approached so near to others, because they consider it asan essential com- the prevailing principles of the present day, that ponent part of water, name hydrogen gass; and he he supposed fire (or caloric) was continually difknew also that it had been observed before him fused through the air. in mioes by Libavius : be convinced himself that The celebrated Spanish mineralogist Alphonso even eructations were of the same nature, and Barba was acquainted with those pernicious that this gass formed a principal component part damps which arise so often in mines, and which, of smoke: he likewise considered flame to be only though they resemble air in other respects, have inflamed smoke, His knowledge, however, was however an offensive smell, extinguish lights, and not confined to this gass alone, for under the deprive men, birds, and even snakes, of their life. name of gass sylvestre he was acquainted with Boyle, to whom natural philosophy in general nitrous gass, produced by the action of aqua-fortis is under so many obligations, though he erred in when silver is dissolved in it; and he knew also ascribing the increase of weight which metals acthat when it came in contact with the atmosphere quire by calcination, rather from the fire than to it formed fiery red vapours.

particles from the atmosphere, was nevertheless He appears to have been acquainted also with acquainted with the carbonic acid gass as it rises from coral, when it effervesces with vinegar, from others which arise from effervescing mixtures, and bread, cherries, grapes, pears, apricots, plums, which suddenly extinguish fame. He observed gooseberries, peas, &c. when they ferment, and its likewise, exceedingly well, the great difference of highly pernicious effects on animals; as also with the nitrous gass which he obtained when he pour. the inflammable, as it partly occurs in abun- ed upon antimony aqua regia, or spirit of nitre ; dance in many mines, for example, those of Hun- or the latter diluted with water (aqua-fortis) upon gary, partly as it arises by a solution of iron in iron filings or quicksilver, and its property of formdiluted sulphuric acid or muriatic acid, and its ing red clouds with common air as soon as it property of inflaming when brought into contact comes in contact with it; and, by repeated expewith flame.

riments, that it absorbed a great portion of air ; The latter-as a highly pernicious kind of gass, and also, that the oftener the experiment was reabundant in coal-pits, is mentioned by Martin peated, the gass always absorbed the less air; that Lister, Jessop, and P. R. Moslyn; and a fire several of these gasses were absorbed by water; which took place in a coal-pit by the inflamma- how much the best air is corrupted by the breathtion of such vapour is mentioned by Hodgson, in ing of even the soundest men, so that at last it is the Philosophical Transactions for 1676.; a like totally unfit for respiration. He knew also the va pour was found about the same time by Beau- ammoniacal as well as the moriatic acid gass, and mont in other subterranean holes; by T. Shirley the sulphuric acid gass, and had learned, from bis above a spring, and Wolfstriegel and Vollgnad in own experience, that the latter can be as strongly a spring. Pope, in the first volume of the Philo- compressed as common air. He knew also that sophical Transactions, gave a very lively picture inetals increase in weight by calcination, and of that corrupted kind of gass in a hole near the again decrease on being revived; for he found that lake of Agnano; and L. A. Portius and Leonhard red lead in the preparation had increased in weight à Capua, that of Grotto del Cane, and other ca- about a twentieth part, and by a strong heat gave verns in the neighbourhood of Naples; E. Hagen- a great deal of air; his own experience had taught dorn and F. Hoffmann, the dangerous quality of him also that phosphorus, sulphar, and a tallow air in which coals have been burnt; and T. Birch, candle, absorb some of the air in which they in 1668, that of air which has been corrupted by burn, as animals absorb some of the air in which the breath of animals. S. Ledelius mentions the they breathe, though he ascribed the pernicious death of a person which took place in a cellar fillo change which the air thereby experiences, not to ed with wine in a state of fermentation. This gass, the loss it sustains, but rather to the corrupt eraas it rises both from fermenting liquids as well as poration with which it is filled. He had observed, from lixivious salts and earths, when they effer- though less perfectly, that phosphorus after comresce with acids, and in which, even in his time, bustion increased in weight by imbibing something Bernoulli sought for the cause of this effervescing, from the atmosphere. He had discovered that an was perfectly well known to sir Christopher Wren, aëriform substance was contained in acidulous in 1675. He relates a method by which such waters, and that air was continually absorbed by fuids can be collected and preserved in vessels; plants in a healthy state.' See his Statical Essays, and he knew that the above gass is absorbed by passiin. water, and he distinguishes it very clearly from In this difficult doctrine, however, he left a nitrous gass. Even the nitrous gass of the mo- great deal to be explained by his followers; for he dern's seems to have been known to Huygens and did not define and was not acqua nted with the Papin, for they relate, that they obtained such a difference of many of the gasses, and some of them fuid from the mixture of spirit of wine and spirit escaped his notice altogether. The further illusof nitre under the receiver of an air-pump. tration of them was reserved for the moderu che

At the same period, F. Slare and T. Willis mists. Thus, in particular, the following authors ascribed the dark red colour of the blood to the have very much contributed to enlarge onr knowair; and J. Mayow, another Englishman, with ledge of the carbonic acid :--Dr. Black, in 1764; whom another Oxford physician, Henry Mand, T. Henry, in 1773; the Dutch naturalist, D. De and also Willis, L. M. Barbieri, and J. B. Giovan.. Smedt, in the same year; T. A. Emmer, in 1784. ni, concorred, made the whole use of breathing to Among the Germans, N. C. Jacquin, in 1769; and consist of this--that the lungs of animals inhale J. J. Well, in 1772. Among the Italiaus, Fontana, from the atmosphere nitrous particles, which are in 1774. In Switzerland, Sol. Schintz, in 1778, diffused over the animal spirits and communicate and in Sweden, sir Tobias Bergman. The last warmth to the blood. J. N. Pechlin, also, attri- mentioned chemist shewed also, as did Brownrigg butes the faculty of some divers being able to re- in England, and Venel in France, that acid waters main longer under water to a greater quantity of are principally indebted to this substance for their Ditre. From all this, it appears, that the playsi- properties; so that several chemnical authors, such cians of that period had a kind of idea of vital air, as Bergman, Rouelle, Duchunoy, Laugier, Meyer, and its influence on the animal economy. and Kostlin, have described the process by which

Stephen Hales, who made further progress by they can be exceedingly well imitated. bis numerous experiments in discovering the se- With the like care and ingenuity, the following crets of nature, placed beyond all doubt, by a writers have examined the nature of the inflamlong series of experiments, the elasticity of these mable kinds of gass: Lassone, in 1766; Volta, in fluids as they are expelled from bodies by heat, 1777; Senebier, of Geneva, in 1784; Minkelers, fermentation, corruption, and effervescence, a of Lovain, in 1784; Kirwan, in 1786; Moscheni, power which was before observed by Newton, and of Lucca, in 1789; Gengembre, and Raymond, in at the same time showed several and ingenious 1791; Nieuwland, Deiman, Froostwyk, and Bondt, methods how they could be observed, preserved, in 1792. The three last, together with Lanremmeasured, weighel, and even handled. He re- burg, examined the different kinds of inflammable marked the inflammability of those which the in- gass. flammable bodies of every kingdom of nature yield The dephlogisticated nitrous air of Dr. Priestley, by exposure to a strong heat, the properties of now calied nitrous gass, has been also examined

by Fontana, Bochante, Deiman, Bondt, Nieuw- gasseous form, and of which different proportions land, Footswyk, &c. &c. Azotic gass was noticed are required to combine with different substances. by professor Schnuidt in the first volume of Gren's We are not able to set a limit to the number of Journal; Wieglib in Creli's Aonals, in 1796; and bodies which inay be made to assume this form, a multitude of writers since. The inflammable or to that of the various processes and combinamuriatic acid gass was treated by Westrumb in tions during which gasses are involved. Crell's Annals for 1790, &c.

In order to reduce any substance to the state of But this new field in the province of natural gass, the application of caloric may be made in knowledge has been cultivated in a more extensive different ways. The most simple method consists manner, by a variety of authors, who have not con- in placing the body in contact with another body fined their attention to one or two gassés, but that is heated: in this situation, the caloric on have investigated with more or less precision and one hand diminishes the affinity of aggregation or advantage all that they had an opportunity of ex- composition, by separating the constituent prinamining. in Italy, Barbarigo, Fontana, Bucci, ciples to a greater distance from each other; and and Volta; in France, Berthollet, Bucquet, Cor- on the other hand, the caloric unites with the rinus de la Metherie, Rouland, Sigaud de la Fond, principles to which it bas the strongest affinity, Thourenel, Lavoisier, Fourcroy, &c.; in England, and volatilizes them. This process is accord Keir, Planket, Cavallo, Cavendish, Higgins, &c. ing to the method of simple affinities; for, ia &c.; in the Netherlands, Froostwyk and Deiman; fact, it consists of the exhibition of a third body, in Germany, Achard, Herbert, Leonardi, Weber, which, presented to a compound, combines with &c. But among the philosophers who have ex- one of its principles, and carries it off. The meplained and illustrated the nature of these gasses thod of double affinity may also be used for the bę numerous experiments, made with great care same purpose; as when we cause one body to act and accurately described, none have distinguished upon another to produce a combination, in which themselves more than Scheele and Dr. Priestley, a disengagement of some gasseous principle takes The former a native of Germany, but settled in place. If, for example, sulphuric acid be poured Sweden, invented very simple processes, yet well upon oxyd of manganese, the acid combines with calculated to answer the proposed end, of examine the metal, while its caloric seizes the oxygen, and ing these gasses, by which means he discovered rises with it. This takes place, not only in the bew kinds, and proved the existence of those ale instance we have quoted, but on all other occaready known in a much clearer method than had sions wherein an operation being performed with beeo dune before in bis Abbandlung von der Luft out the application of heat, there is a production und dem Feuer nebst einem Vorbericht von 'l. of vapour or gass. The various states under which Bergman, Upsal and Leipsic, 1777, 8v0.; and in bodies present themselves to our eyes, depend Kongl. Svensk. Vetenskap. Acadein. Handling, almost entirely upon the different degrees of com1774, p. 84. The latter, being furnished with a bination of caloric with these bodies: tiuids do not more extensive apparatus, placed in a clearer differ from solids, nor gasses from fluids, but bepoint of view not only the nature and differences cause they possess such a quantity of caloric as is of the gasses before discovered, but discovered requisite to maintain them in one or the other new ones also. An account of bis experiments state respectively. For the methods employed in may be seen in Experiments and Observations on preparing the different kinds of gass, we refer to the different kinds of Air, London, 8vo. vol. i. their names. 1774, vol. ii. 1775, vol. iii. 1777; Experiments 3. Modes of collecting and transferring the gasses.and Observations relating to various Branches of It was not long after the discovery of the gasses, Natural Philosophy, with a Continuation of Ob- and the proof of their diversity, that methods were servations on Air, 8vo, vol. i. London, 1979, vol. devised to manage them at pleasure. Dr. Priestley, ii. Birmingham, 1782, rol. iii. 1790; Directions the most successful, though not the earliest cultifor in pregnating Water with fixed Air, &c. Lon- vator of this department of chemistry, the extendon, 1772,8vo.; Poilosophical Transactions of the sion of which forms a most important era in the American Society, 1796; and various other works history of the science, was the first who effected a within this period may be consulted with advan- contrivance by which these singular fluids may be tage.

collected, retained, transferred from one vessel to In consequence of these researches, the nature another, and subjected to every variety of experiof gasses in general became better understood, and ment at the will of the operator. The principal their characteristic properties were ascertained article in the pneumatic apparatus is the trough, with sufficient accuracy to point out and establish resorvoir, or cistern, which has been much improve a clear distinction between the individual gasses. ed in point of convenience since it was first invent. Hence, therefore, it is unnecessary to pursue our ed; though the principle of its construction is rebistory farther in this place; for, though these tained. The present form of this vessel is representinteresting fluids bave recently engaged, more uni- ed in fig. 1. Pl. 77. It may be made either of wood versally than ever, the attention of philosophers, lined with leather, or of sheet iron, tinned, japanthe discoveries which have been made respecting ned, or painted : wood alone is not so proper, beeach will admit of a more convenient arrange cause if not kept full of water it will become leaky. ment under the name of the particular gass to A little below its brim a shelf AB is placed, about which they relate.

a half or third part as wide as the trough; in this The gass arising from the distillation of coal bas shelf are several boles, each terminating a funnellately been applied, on a large scale, to the illumi- like excavation, the widest part of which is on nation of bouses, manufactories, streets, &c. the under side of the shelf. The use of the shelf

2. Formation of gasses.-Every individual gass is is to support receivers, jars, bell-glasses, or other supposed to be forned of two eleinents; the par- vessels intended to contain the gass. To use the ticular substance which gives name to the gass, trough, so much water must be poured into it as and is called its basis--and caloric, by the ex

is sufficient to cover the shelfto the depth of about pansive power of which it is made to assume the an inch; and the receiver being filled with water in the deep part, must be placed invertedly on the vessel that is stopped like a bottle, it must be unshelf, its open end turned down upon one of the stopped with its orifice downwards in the water, holes; the gass then being conveyed to the under and then inclined in such a manner that its neck part of the excavation by means of a curved or may come under the excavation of the shelf. The other tube, or suffered to escape from its former gass will escape from the bottle, and passing vessel, will ascend through the hole into the re- through the hole into the vessel intended to receiver, displacing the water as the quantity of ceive it, will ascend into the form of bubbles as gass increases. This trough may be made of vari- before. Sometimes a bent glass tube, such as apous sizes, according to the purpose for wbien it is pears connected with the fusk in fig. 7, is employintended : one of about two feet long, 16 inches ed to conduct the gass under the water or mercury wide, and 15 high, will be found sufficient for into the receiver. Some other methods occasion. most experiments. Sometimes, however, a much aily resorted to, particularly in collecting gasses larger one is necessary; and in laboratories, where for distillations, will be noticed in the article a considerable number of experiments are per- PNEUMATIC APPARATUS. formed, it is also requisite to have several smaller 4. Dilation or expansion of gasses. The influence ones, which may be moved when necessary near of caloric, in dilating or expanding bodies, has a furnace, or wherever they may be wanted. Fig. beeu long known as a fact; though the laws by 2. represents a jar, being filled with gass, standing which this influence is regulated are not even now in a dish containing water, and having two handles perfectly ascertained. In general it is observed to transport the vessels from one cistern to an. that the expansion of bodies is greatest in their other, or for keeping them in reserve when the gasseous form, less in their fuid, and least in their cistern is too full.

solid state; as an example, it is known that the A more commodious method of constructing expa of air is inore than eight times greater the pneumatic trough is shewn in fig. 3.; where aa, than that of water, and that of water is about 45 is the well to contain the water for Gilling the ves- tiines greater than that of iron. Many experisels, &c.; bb, a small shelf with holes; and on a ments have been made to ascertain the rate of exlevel with it the surface cc, covered also with pansion in gasses according to the elevation of water; and not more than two or three inches dis- temperature; bat the results obtained were so tant from the brim; dd, depressions, or hollows, various, on account chiefly of the want of sufficito receive the curred necks of bottles, or the ent care to exclude water from the vessels in curved ends of tubes; eee, vessels invented on the which the expansion was measured, that for a long surface of the trough; f, a large shelf underneath time no settled opiniou could be formed on the subto contain vessels for use. Instead of a rectan- ject. At length, however, the problem engaged gular, some persons prefer a curvular, and others the attention of two very ingenious and precise an oval shape for their troughs.

philosophers, whose experiments agree in furnishSome of the gasses are capable of being absorbed ing a conclusion as curious as it was unexpected; by water, and therefore cannot be collected by namely, that the progress of dilatation is absolutely means of the above apparatus. When that is the equal in all the different kinds of gass; or that all case, mercury must be used; and on account of the different clastic fluids, taken at the same temits gravity and dearness, a smaller trough, formed perature, expand equally by heat: that all the somewhat differently, must be employed; as re- different gasses, from the lightest to the heaviest, presented in figs. 4. and 5., of which the first is a taken at temperature, are equally expanded by perspective view of the spherical cavity and caloric. The experiments of Mr. Dalton were groove to be filled, and something higher with read to the philosophical society at Mauchester, mercury; the receiving vessel is likewise to be in October, 1801, and published in 1802: the disa filled with that metal and inverted. Fig. 5. a sec- sertation of Gay Lussac did not appear in the tion of the same, shewing the manner of placing Ann. de Chim. (vol. 43), till more than six months the receiver, and the neck of the retort, or other after: our own countryman must therefore be revessel, from which the gass is to be supplied. garded as the original discoverer of this important The receiver ought to be of smaller diameter, and law. Mr. Dalton's experiments are distinguished inuch stronger than when water is employed. A by a simplicity of apparatus which adds greatly to mercurial trough may be cut out of marble free their value, as it puts it in the power of others to stone, or a solid block of wood; but the first is repeat them without difficulty. It consists merely preferable. A trough of about twelve inches long, of a glass tube, open at one ead, and divided into three wide, and four deep, besides the gutter or equal parts; the gass to be examined was introgroove, is sufficient for all private experiments, duced into it, after being properly dried, and the

In order to acquire expertness in transferring tube is filled with mercury at the open end to a the gasses, it would be advisable for the cheinical given point; heat is then applied, and the dilatastudent to begin his operations with common air, tion is observed by the quantity of mercury wbich by collecting and transferring which he would soon is pushed out. See Manchester Memoirs, vol. v. be qualified to manage any of the other gasses. Mr. Gay Lussac's apparatus is more complicated, The bell-glass, or other receiver, being filled with but equally precise; and as his experiments were water, and placed with its mouth downwards over made on larger bulks of air, their coincidence with one of the holes in the shelf of the trough, let a those of Mr. Dalton adds considerably to the conglass or other vessel be plunged into the water fidence which may be placed in the results. These with its mouth downwards; the air within the experinents are detailed, and the apparatus devessel will prevent the entrance of the water; but scribed in Annal. de Chim. xlii. 187; they may if it be turned up, the water rushes in, and the air also be seen in Nicholson's Journal, N. S. vol.iii. rises in bubbles to the surface: if this be done Still, however, though Gay Lussac found the dila* under the receiver, the air will descend through tation to be from 100 to 137.5 betwcen 32° and the hole, and rising to the upper part of the jar, 212% of Fahrenheit, the precise expansion for ipwill there be detained, and expel part of the water crements of single degrees was by no means deịt contains. If the air is to be transferred from a termined, nor does it appear yet to be attained

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