We have dwelt so long upon the first volume, that we shal! only have time to take a hasty view of the contents of the second, It begins with a chapter on the chemical conposition of the atmosphere, in which the subjects of eudiometry, combustion, oxygen, nitrogen, &c. follow in succession. The author is probably master of the established facts and prevailing doctrines on all these opics, but that does not prove that he is able to write upon them. Before a person presuines to be an author, he should either have something new to impart, or he should be certain that he is able to place what is old in a new point of view; but we do not find that Dr. Robertson has accomplished either of these objects. Now we must declare that we think it quite unnecessary to publish two octavo volumes to inform the scientific work, that oxygen supports life and flame, that nitrogen cannot support them, that carbonic acid is generated by respiration and combustion, that an animal can live, or a taper burn, for a limited time only in a given quantity of air, and other such elementary propositions. Such facts were interesting in the days of Boyle and Mayow, but after the Jabours of Priestley and Lavoisier, we require something farther to form the basis of a learned pub lication. The influence of the atmosphere upon animals and vegetables is copiously discussed, but not in such a manner as to entitle the author to much commendation. We have again to lament the want of that nice discriminative faculty, which may enable him, amidst the discor 697 dant opinions that are met with on the subjects of physiology, to know in which of them he ought to place confidence, and which he ought to reject as unworthy of credit. Had he possessed this desirable talent, he would not have thought that the lungs possess a power of dilatation independently of the thorax, because M Bremond has written a paper in the memoirs of the Academy to prove that this is the case, nor would have believed that air which has been kept in contact with blood becomes inflammable, on the authority of Guitanner. Only a few admissions of this kind, interspersed through much of what may be really valuable, necessarily throws a shade of insignificancy over the whole performance, and impresses the reader with the opinion, that he is under the direction of one who is unqualified to act as a guide through the intricate paths of science. With these observations we shall close our remarks upon Dr. Robertsou's work. It displays a considerable share of industry, and is probably the result of a good deal of reading, but books must be understood as well as read, and facts must be digested as well as transcribed, before they can be applied to any valuable purpose. It is no gratification to us to be severe in our criticisms, on the contrary, it is always pleasing to us to be able to commend, but justice must be heard in opposition to civility, and we apprehend that our readers would have a very fair subject of complaint against us, were we, out of compassion to the author, to lead them to toil through these uninteresting volumes. ART. VIII. Philosophical Transactions of the Royal Society of London, for the Year 1808, 4to. OF the present interesting voJume we shall proceed to lay before our readers as copious an account as the limits within which we are restricted by our own plan will permit. 1. The Bakerian Lecture, on some new Phenomena of chemical Changes produced by Electricity, particularly the Decomposition of the fixed Alkalies, and the Exhibition of the new Substances that constitute their Bases; and on the general Nature of alkaline Bodies, by H. Davy, Esq. Sec. R. S. M. R. I.A. 23. Electro-chemical Researches, on the Decomposition of the Earths; with Observations on the Metals obtained from the alkaline Earths, and on the Amalgam procured from Ammonia. By H. Davy, Esq. Sec. R. S. M. R. I. A. The discoveries of Mr. Davy recorded in the above papers would be of themselves sufficient to entitle any one to a very high rank among experimental philosophers; but when we call to mind that they form part only of a series, the splendid commencement of which has been already disclosed to us in the preceding volumes of the transactions, and the further progress of which will, no doubt, be answerable to the high expectations thereby excited, we are surely justifiable in regarding their author as the greatest genius at present alive in the different walks of scientific research. Taking for granted that no one conversant with chemical enquiries will be so incurious as not to bestow on these two interesting papers his special attention, we shall here state only some of the principal results. Having already successfully applied the agency of electricity in the decomposition of several of the neutral salts and other substances, the component elements of which were well known, Mr. Davy resolved to submit to its action other bodies which had not as yet been decomposed. The first substance operated on with this view was potash. After some preliminary experiments in which its compound nature was very apparent, the complete resolution of it was effected in the following manner. se "A small piece of pure potash, which had been exposed for a few conds to the atmosphere, so as to give conducting power to the surface, was placed upon an insulated disc of platina, battery of the power of 250 of 6 and 4, in connected with the negative side of the a state of intense activity; and a platina wire, communicating with the posi tive side, was brought in contact with the upper surface of the alkali. The whole apparatus was in the open atmosphere. "Under these circumstances a vivid action was soon observed to take place. The potash began to fuse at both its points of electrization. There was a violent effervescence at the upper surface; at the lower, or negative surface, there was no liberation of elastic fluid; but small globules having a high metallic lustre, and being precisely similar in visible characters to quicksilver, appeared, some of which burnt with explosion and bright flame, as soon as they were formed, and others remained, and were merely tarnished, and finally covered by a white film which formed on their surfaces. "These globules, numerous experiments soon shewed to be the substance I was in search of, and a peculiar inflammable principle the basis of potash. I found that the platina was in no way connected with the result, except as the medium for exhibiting the electrical powers of decomposition; and a substance of the same kind was produced when pieces of copper, silver, gold, plumbago, or even charcoal, were employed for compleating the circuit. of the presence of air; I found that it "The phenomenon was independent took place when the alkali was in the va cuum of an exhausted receiver." When the decomposition was effected in glass tubes, the metallic base arranged itself round the negative wire, and from the positive one was given out a gas that on examination proved to be pure oxygen. The metallic globules themselves on exposure to the air, immediately became covered with a white crust of potash which as soon as formed began to attract moisture, and this last in its turn was rapidly decomposed by he remainder of the metal, so that the whole was in a very short time converted into regenerated potas. When the metal was heated in a glas tube, in contact with oxygen, a rapid combustion took place, oxygen was absorbed, and potash wa reproduced. The attraction of this new metal, or potassium, for oxygen is so great, that like the imaginary alkahest of the alchemists, there is scarcely any thing which will detain it a sufficient time for examination when immersed however in recentlydistilled naphtha, it may be preserved for some days without any material alteration. The properties of this remarkable substance are the following. At 100° Fahr. it is perfectly fluid, and possesses the mobility, colour, and lustre of pure mercury at 50° F. it becomes a soft malleable solid greatly resembling silver, and at 32° F. it is quite brittle, and presents a granular crystallized fracture; at a red heat it is volatilized, and with due precaution may be collected again unaltered. It is a perfect conductor of heat and electricity, but differs most remarkably from the other known metals in specific gravity, being no more than about 0. 6. when fluid, and a little heavier when solid. When heated with a sufficient quantity of oxygen it is converted into potash, but with a smaller quantity it assumes the appearance of a greyish brown solid, consisting of potash and oxyd of po. tassium, which by the addition of a further portion of oxygen, becomes pure alkali. In oxymuriatic acid gas it burns with a bright red light, and muriat of potash is the result. It is soluble in hydrogen at a temperature inferior to a red heat, forming a gas, which detonates with a bright light and alkaline fumes when mixed with common air; but by cooling, the whole of the potassium is deposited, and the hydrogen re mains unaltered. If a globule be placed on a piece of ice, it instantly burns with a bright flame, and is converted into a solution of potash : the same appearance takes place if the globule is touched with a drop of water. It decomposes nitric and sulphuric acids with remarkable energy. It combines with phosphorus and sulphur forming compounds analogous to the other metallic phosphurets and sulphurets: at the moment of combination with the latter of these two bodies, heat and light are given out, and sulphuretted hydrogen is disengaged. It unites very readily with mercury, forming a solid amalgam, if the proportion of this latter is not more than as 70. to one, by weight. When this amalgam is exposed to the air, potash is rapidly produced, and the mercury remains pure. Potassium also combines with gold, silver, and copper. The strong affinity of this new metal for oxygen enables it to reduce with ease the oxyds of lead, tin, and iron, at the same time that itself reacquires the alkaline form. Soda exhibits in general the same results as potash, but with the following differences. Its metallic base is of a white colour, and resembles silver in its external appearance. It is very soft and malleable at the common temperature. Its specific gravity is about 0. 93. It is fusible at 180° Fahr. but is not volatilizable at the temperature of melting glass. It absorbs oxygen more slowly than potassium does. It is not soluble in hydrogen gas when heated. It decomposes water with great energy, but no flame makes its appearance, except the quantity of water is very minute. When added to mercury in the proportion of, the result is a solid amalgam. With regard to the constituent parts of these two alkalies, it appears that potash consists of 86. 1. basis and 13.9. oxygen; and soda of 80 basis and 20 oxygen. The presence of oxygen in the fixed alkalies oxy induced Mr. Davy to examine whether ammonia, which is usually con sidered as composed of hydrogen and azot, did not also contain gen; and the result of the enquiry was, that the presence of this latter substance in the proportion of about 7 per cent, is rendered highly probable. In consequence of a communication from Professor Berzelius and Dr. Pontin relative to the deoxydation and analgamation of the base of ammonia, Mr. Davy insituted the following very interesting experiments. "I made a cavity in a piece of muriate of ammonia; into this a globule of mercury, weighing about fifty grains, was introduced. The muriate was slightly moistened, soas to be rendered a conductor, and placed on a plate of platina, which was made positive in the circuit of the large battery. The quicksilver was made negative by means of a platina wire. The action of the quicksilver on the salt was immedi ate; a strong effervescence with much heat took place. The globule in a few minutes had enlarged to five times its former dimensions, and had the appearance of an amalgam of zinc; and metallic crystallizations shot from it, as a centre, round the body of the salt. They had an arborescent appearance, often becaine coloured at their points of contact with the muriate; and when the connection was broken, rapidly disappeared, emitting ammoniacal fumes, and reproducing quicksilver. "When a piece of moistened carbonate of ammonia was used, the appearances were the same, and the amalgam was formed with equal rapidity. In this process of deoxydation, when the battery was in powerful action, a black matter formed in the cavily, which there is every reason to believe was carbonace. ous matter from the decomposition of the carl on c acid of the carbonate. "When mercury, united to a small quantity of potassium, sodium, Larium, or calcium, was made to act upon moistened muriat of ammonia, the amalgam rapidly increased to six or seven times its volume, and the compound seemed to than that procured by electrical powers. contain much more ammoniaca! basis "As in these cases, however, a por tion of the metal used for the deoxydation always remained in union in the compound; in describing the properties of amalgam from ammonia, I shall speak only of that procured by electrical means. "The amalgam from ammonia, when formed at the temperature of 70° or 80, is a soft solid, of the consistence of butter; at the freezing temperature it be comes firmer, and a crystallized mass, in which small facets appear, but having no perfectly defined form. Its specific gravity is below 3, water being one. "When exposed to air it soon be. comes covered with a white crust, which proves to be carbonate of ammonia. "When thrown into water it produces a quantity of hydrogene, equal to about half its bulk, and in consequence of this action the water becomes a weak solution of ammonia. "When it is confined in a given portion of air, the air enlarges considerably in volume, and the pure quicksilver reappears. Ammoniacal gas, equal to one and a half or one and three fifths of the volume of the amalgam is found to be produced, and a quantity of oxygene equal to one-seventh, or one-eighth of the ammonia, disappears. "When thrown into muriatic acid gas, it instantly becomes coated with muriate of ammonia, and a small quantity of hydrogene is disengaged. "In sulphuric acid it becomes coated with sulphate of ammonia and sulphur.” All attempts however to separate the new metal from the mercury were without success. The above discoveries with re "The strong attraction of potassium, sodium, and the metals of the alkalinegard to the alkalies naturally led to earths for oxygene, induced me to examine whether their deoxydating powers could not be made to produce the effect of the amalgamation of ammonia, independently of the agency of electricity; and the result was very satisfactory. earths, from which, notwithstandsimilar experiments ou the alkaline ing their infusibility, very decisive evidence was obtained of the compound nature of these bodies, and their strong analogy with the fixed alkalies. The other earths have not yet been so satisfactorily decomposed, though there is every probability that this problem will shortly be resolved. For the profound and interesting theoretical deductions from the foregoing facts we refer the reader to the original memoirs. 2. On the Structure and Uses of the Spleen, By Everard Home, Esq. F. R. S. 11. Further Experiments on the Spleen. By the Same. As these papers are not of general interest we shall only quote the following statement of the conclusions established by them. "That the liquids received into the stomach beyond what are employed for digestion, are not wholly carried out of if by the common absorbents of the stomach, or a canal of the intestines, but are partly conveyed through the medium of the spleen into the circulation of the li ver. "The vessels which communicate between the stomach and the spleen have not been discovered: but if it is proved that the colouring matter of the contents of the stomach, is met with in greater quantity in the spleen and in the vein which goes from that organ to the liver, than in the other veins of the body, there appears to be no other mode in which it can arrive there, but by means of such vessels; and the two different states of the spleen, which correspond with the quantities of liquids that pass from the stomach, are strongly in favour of the existence of such a channel. "This communication between the cardiac portion of the stomach, and the spleen, will explain the circumstance of those who are in the habit of drinking spirituous liquors having the spleen and liver so frequently diseased, and the diseases of both organs being of the same kind." 3. On the Composition of the compound Sulphuret from Huel Boys, and an Account of its Crystals. By James Smithson, Esq. F. R. S. In the transactions for 1804 is a very elaborate analysis of this sub stance by Mr. Hatchett, which from the well known accuracy of this chemist, has been selected by Mr. Smithson for the illustration of a new theory of the mode of chemical composition. It consists of the two following propositions. That all chemical combination is binary, no substance whatever having more than two proximate or true elements; and that the proportions in which bodies combine may be reduced to very simple ratios. The theory is ingenious and plausible, but requires a much more profound investigation than it has yet received before it can be admitted. 4. On oxalic Acid. By Thomas Thomson, MD. F.R. §. Éd. This is a very excellent paper, and well worthy of Dr. Thomson's known accuracy and ability. It contains a complete chemical history of the composition and properties of oxalic acid and its neutral and former chemists are corrected, and earthy salts; in which the errors of many new and interesting facts are contributed to the common stock. The latter part of the paper is a very ingenious application of Mr. Dalton's theory, explanatory of the composition of sugar, and the process by which oxalic acid is formed from this substance by the agency of nitric acid. Salts. ByW. II. Wallaston, M.D. Sec. 5. On Super-acid and Sub-acid R. S. This paper is intimately connected with the two preceding; and is intended to illustrate the theory, that in all cases the simple elements of bodies are disposed to unite atom to atom singly, or if either is in excess, such excess is a ratio that may be expressed by some simple multiple of the number of its atoms. 6. On the Inconvertibility of Bark into Alburnum. By Thos. Andrew Knight, Esq. F. R. S. 20. On the Origin and Office of the Alburnum of Trees. By the same. |