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nesia, and oxide of iron. It is most the Seltzer water contains in an probable that this water also, previous English pint : to evaporation, contains muriate of

Carbonic acid gas,

17 cubic inches. lime, which is acted on by the sul

Carbonate of lime, 3 grains. phate of soda during the analysis.

Carbonate of magnesia, Probably the carbonate naturally in Carbonate of soda,

4 the water is carbonate of soda, which, Muriate of soda,

17.5 re-acting on sulphate or muriate of magnesia, produces carbonate of mag- According to Dr Murray's view, nesia and sulphate or muriate of soda, the composition will be: It is much more probable, from the

Carbonic acid gas,

17 cubic inches. known insolubility of carbonate of

Muriate of lime,

3.3 grains. magnesia, that it is produced in this Muriate of magnesia, way, than that it should exist in a Muriate of soda,

7.8 state of solution in so large a quantity

Carbonate of soda, dry,

(equivalent to 18 crysas that which is afforded by the eva


10.3 poration.

The water of Harrowgate yields This accords much better both muriate of soda as its chief ingre- with its sensible qualities and its dient, iron joined with muriate of medicinal powers. Its strongly almagnesia, muriate of lime, sulphate kaline taste, when the excess of carof magnesia, carbonate of magnesia, bonic acid has escaped, is scarcely arid carbonate of lime. The two last accounted for by three grains of carsubstances most probably are not ori- bonate of soda, but very well by 18. ginal ingredients, but formed during It has a high reputation as an antacid the analysis by the action of carbon and diuretic, also in dyspeptic cases, nate of soda, existing in the water, diseases of the urinary organs, and on portions of its muriate of mag- general debility; all of which powers nesia and muriate of lime, whence are explained in a much more satisalso the muriate of soda is increased. factory manner by this new view of

The valuable foreign mineral wa- their composition. Dr Murray has ters of Spa, Pyrmont, and Seltzer, succeeded in shewing that the statecalled the alkaline carbonated waters, ments hitherto given of the composiare largely impregnated with carbo- tion of mineral waters have proceednic acid gas, and containing a consi- ed on rash principles. The existence derable quantity of carbonate of soda, of the same neutral salts in solution with which are associated carbonate which analysis evolves in the crysof magnesia, carbonate of lime, and tallized form, is at least questionable, muriate of soda. The real ingre- and we may almost say disproved. dients of these waters are most pro- This chemist still adheres to the idea bably carbonate of soda, mariate of that they consist of binary neutral magnesia, and muriate of lime; and salts; but he thinks that the most sothe carbonate of soda existing in luble, and consequently those which larger proportion than that indicated are the least apt to be evolved by evaby the analysis, acts during the eva- poration, are the real ingredients.- It poration of the water on the muriates might, however, be maintained that of magnesia and lime, and forms the all the primary ingredients of the comcarbonates of these earths, together pound salts obtained by analysis, that with some muriate of soda.

is, the acids and neutralizable bases, According to Bergman's analysis, exist in simultaneous combination in the water. This would afford a far tensive to admit of any abstract in this better explanation of their active place. It is sufficient to remark the adpowers than the composition usually vantage imparted to the results by the assigned to them. They might still application of the methods of reasonbe viewed as very active solutions; ing which he had adopted with regard they might be considered as equally to mineral waters. He is in this way powerful with the most soluble and enabled to reconcile with one another the most active salts which they are the analyses given by his predecescapable of forming by binary combi- surs, sometimes at'variance. For exnations. It is not altogether impos- ample, he accounts for the singularity sible that their simultaneous combi- which appeared in that of Lavoisier, nation might even confer additional who obtained from it portions of sulpowers. Probably most chemists will phate of soda and muriate of lime, incline to adopt this view of the sub- ingredients found by no one else. Dr ject. Dr Murray rejects it, because, Murray, in repeating with exactness if fairly followed out, it would lead to the process of Lavoisier, as well as the conclusion that all combinations those of other chemists, found that of compound bodies are simultaneous the difference of result depended on combinations of the primary elements the process employed. The alcohol -aconclusion from which no inference employed by Lavoisier favoured the with regard to specific qualities could formation of the crystals which he be drawn, and which would, therefore, obtained. be inconsistent with the conclusions The separation of the different salts w!rich, in many cases, we are able ac- by crystallization is tedious and diffitually to form. It is probable that cult, and seldom perfect in the end ; most other chemists will see less and, as this laborious mode of proceweight in this objection, and will be dure gives us no information regarddisposed at least to acknowledge that ing the mode of existence of acids, althe exact relations subsisting between kalis, and earths, in a mixed chemical the primary ingredients of a complir solution, he proposes that we should, cated compound, whether in a fluid in all such cases, satisfy ourselves or in a solid state, lie probably for ever with determining the acids and salifi. beyond the reach of actual determi- able bases and their respective pronation. This consideration itself pre- portions, by means of reagents which pares us to acknowledge with less have the power of precipitating them. mystery or reluctance, the existence He found in a pint of the sea water of any powers in mineral waters to which he employed, which experience lends its counte


2.9 grains. nance, and, where the facts are in

Magnesia conformity to the presence of such Soda a state of combination as can be at Sulphuric acid

14.4 all assigned to the simple ingredients,

Muriatic acid.

. 97.7 we can be at no loss to say that all

226.1 the powers which such a state implies are explained as the result of the These he supposes to exist in the composition; and, in addition to this, following state of combination :we may conceive other accumulated Muriate of soda .

159.3 grains chemical agencies to be at the same

Ditto of magnesia time concerned in the operation.

Ditto of lime.

5.7 The labours of this chemist in the

Sulphate of soda . “ Analysis of Sea Water,” are too ex

226.1 VOL. XI. PART 1.

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Following up these improved views, ciples. These do not admit of he lays down, in his third Memoir, abridgment; and, therefore, we must A formula of general application satisfy ourselves with a reference to for the analysis of mineral waters." the author's Memoir, not doubting He adheres exclusively to that method that it will be quickly copied from which has been usually called the in- the Transactions into works more exdirect, which consists in discover- tensively circulated among personsining the acids and bases, without de- terested both in general and in pracciding anything regarding their mode tical chemistry. In the course of it and order of combination ; while the some acute remarks, in the form of direct method consisted in the ob- improvements, suggested by the autaining of separate crystallized or pre- thor's practice in manipulation, and cipitated salts, and solutions contain- substantiated by his own experience, ing only one salt each. This last bad are interspersed, and the whole busibeen considered as giving not merely ness of analysis is likely to derive the ingredients, from which an opi- from them a material degree of acnion or conjecture might be formed curacy, as well as simplification. It regarding their constitution, but as is important farther to remark, that declaring that constitution in the first they are shewn by the author to adinstance. The author, however, ha- mit of an easy extension to the anaving shewn that no direct information lysis of earthy minerals. of this kind is afforded by such analysis, proposes that it should be relinquished as far less satisfactory than the indirect method. In this last, we have FROM THE HIGHER ATMOSPHERE, it in our power to ascertain the proportions of the constituent parts with much greater accuracy; and having done this, we infer the composition by reasoning on such principles as Some very important experiments have been now explained. These were made, a few years ago, with principles, if they do not afford abso- great labour and care by Dr Wells lute certainty, will preserve us from of London, on the temperature of difthe errors of precipitate deduction ferent parts of the surface of the which have been hitherto acquiesced ground, as influenced by the nature in, and enlarge our views of this class of that surface itself. These are deof objects. The salts usually found tailed in his Essay on Dew, containare carbonates, sulphates, and mu- ing one of the most meritorious seriates-of lime, of magnesia, and of.ries of purely experimental investisoda. After trying, in a general way, gations that modern times have prowhat acids and bases are present, duced in the department of meteorousing nitrate of barytes for ascertain- logy, and beautifully elucidating some ing the presence of sulphuric and new and interesting applications of earbonic acids, and nitrate of silver the chemical doctrines of heat. From for muriatie acid ; aseertaining the these it appears, that the same sorts presence or absence of lime by oxalic of surface which give out heat most acid, of magnesia by lime water or powerfully by radiation, and which ammonia, and of any alkaline neutral receive most readily the heat which is salt by evaporation ; he directs a radiated from other bodies, those sur

eries of steps for ascertaining the faces also which radiate cold most proportions of the respective prin readily, (all which qualities uniform


ly co-exist in the same proportion, THE RADIATION OF CALORIC FROM A in any surface, shewing that they de- SURFACE OF THIS KIND TO THE UPpend on the same superficial constitu- PER REGIONS OF THE ATMOSPHERE, tion), are also liable to the greatest re- or to regions altogether beyond its duction of temperature when exposed limits. The upper regions, in fact, in the night to a clear and dry atmo. operate in the same manner with the sphere. For this reason, dew and bottle of snow which, in the experihoarfrost are more copiously deposit- ments of Pictet and others, radiates ed on these surfaces than on others. cold on surrounding bodies. The reduced temperature makes the Professor Leslie has taken up the portions of the atmosphere which subject in a more discriminating and come successively in contact with the accurate manner, reducing the estisurface deposit their humidity. It is mate of such effects to measure and well known to chemists that in this calculation. The results of his inseparation caloric is given out; hence, quiries, and a description of the inin some experiments formerly made genious and beautiful instrument with by Mr Patrick Wilson of Glasgow, which he operated, were given in a which were read to the Royal Society paper read before the Royal Society of London in 1788, and others, which of Edinburgh in March last. Mr are contained in the Transactions of Leslie's opinions on the radiation the Royal Society of Edinburgh, vol. of heat have been long before the Ist, it appeared an inexplicable cir- public, and in this paper they are recumstance that, where dew or hoar- peated and illustrated. He considers frost had been deposited, the tempe. this class of phenomena as depending rature was particularly low. This is on the presence of the air. They do now fully explained. The low state not, according to him, consist in the of the temperature is prior to the de- simple transmission of caloric through position, and the cause of it; and space, but in certain appulses among though that deposition raises the the particles of the air, which protemperature in proportion to its own ceed on all sides in railiations like amount, it does not necessarily raise sound, or like the rippling waves on it to that of the air and other surround- the surface of a liquid, which proing objects. This cold is in itself inde. ceed from the disturbed point, propendent of the presence of moisture, ducing circles which become wider and the dew produced is in propor

as the effect of the impression is tion to the reduction of temperature, extended. It is in their propagaand the impregnation of the air with tion through air that these effects are moisture. The experiments were best (and we may say exclusively) made by placing a number of ther- known to us. It is not easy to ascermometers on the ground ; some on tain the reality of the diffusion of such gravel, others among grass, and others powers through a perfect vacuum; on smooth stone, or on metals ; and but it is in favour of Mr Leslie's it was found that, when the sky was views, that these are propagated overcast even in a slight degree, all more powerfully through a dense the thermometers stood about the than through a very rarefied atmosame degree of temperature; but that sphere. Mr Leslie objects to the term when the sky was perfectly clear, a radiation. He considers the effects great difference took place, -those in produced as a series of internal oscontact with the most radiating sur- cillations, by which the aerial meface always indicating the lowest tem- dium successfully transfers its charperature. The cold is occasioned by ges of caloric, and delivers an ims pression at the end of the chain of which reached the concave metallic communication of the same kind pre- surface were reflected so as to accucisely as it had received at the begin- mulate the effect on the ball placed ning. Mr Leslie tried the difference in a focal situation. After some vabetween the surface of the ground ried experiments suggested by this and the atmosphere a few inches above fact, with a view to the more accuit, by means of the differential ther- rate determination of the laws obmometer. He found, that in sun- served by these impressions, as indishine and calm weather the ground cated by the variations of their amount was sometimes 30 millesimal degrees under different circumstances, he conwarmer than the air only a few inches trived a set of very ingenious and above it. But when the sky happen- useful instruments, by means of which ed to be much overclouded, or when some further facts were made known. strong winds swept over the sur- He exposed a pyroscope in the focus face, the accumulation of heat hardly of a paraboloid to the influence of the reached three degrees. Fresh plough- sky at different times, and to differed land, or a surface spread over ent quarters of the sky at the same with hay, indicated more than twice time.

It was necessary to guard the effect that appeared on fine pas- against the disturbing influence of ture.

wind. This was first done by putting Mr Leslie, in the course of these his pyroscope with the small reflecexperiments, found that, towards tor within a deep pitcher by which evening, if the sky was clear, the the lateral impulses of the wind were thermometer on the ground indicated intercepted; and afterwards, instead a greater cold than in the atmosphere, of this arrangement, he made the re(unless it was protected by a polished Alector sufficiently deep to answer that metal, or a substance which reflected purpose of itself. The form which he the rays of heat,) although the ground adopted was that of a truncated obitself was still warmer than the air. long spheroid of metal, cut through the This led him to suspect, that an oppo- upper focus by a plane perpendicular site impression was by some means to the axis, finely polished on its inner communicated from the atmosphere at surface, so as to reflect the impresthese times, and he was induced to sions of cold or heat, and having the investigate this set of influences. For sentient ball of the pyroscope placed this purpose he introduced, under the in the lower focus. This instrument insentient ball of his pyroscope, (that dicated most fully the action of that is, that ball of the differential ther- quarter of the heavens to which it was mometer which remained without a turned. He therefore had an instrumetallic covering, while the other ment which was mounted on a pivot, had one, and which consequently so as to be conveniently turned to was most readily operated on by those any portion of the heavens which it impressions of temperature proceed- was his object to explore. This ining from distant bodies which are strument, when covered with a thin called radiations), under this he in- plate of glass, often shewed one or troduced a small circular plate of tin iwo millesimal degrees of heat, the hammered into a slight concavity. effect of the radiation of the light of This more than doubled the action

It was when this screen of the instrument, and, therefore, put was removed, and the reflecting sur. the existence of these impressions face and sentient ball exposed beyond all doubt. . The radiations sky, without any intermedium except

the sky.

to the

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