heads, and logwood: of the latter, bark and jalap. They are evaporated in a saturated salt-water bath. Among the distilled waters, that of sage is omitted: among the volatile oils, that of spear-mint, and the animal oil. In the spirits, we observe no alteration. As the class of oleosa is managed, they are external medicines, and should have been styled liniments. We believe the 'ol. sulphuratum' is now never given internally. The 'oleum lini cum calce' only is new, and made with equal parts of limewater and linseed-oil. The 'sales and salina' are an important class, and greatly improved. The acidum acetosum forte is the radical vinegar of the chemists, distilled from acetis plumbi. In making the muriatic and the nitrous acids, the proportion of the sulphuric is increased to sixteen ounces: it was formerly a pound. The nitric acid is now first introduced. The acidulated kali and soda waters are introduced under the titles of aqua supercarbonatis potassæ et soda.' The sulphuretum potassæ is the old hepar sulphuris, now first introduced or restored; the 'hydrosulphuretum ammonia' is the hepatic mineral-water. The directions for preparing the muriat of barytes and muriat of lime, we shall transcribe. • MURIAS BARYTÆ. R. Sulphatis barytæ libras duas, Carbonis ligni in pulverem triti uncias quatuor. Igne torreatur sulphas, quo facilius teratur in pulverem tenuissimum, cui bene admiscendus est pulvis carbonis ligni. Indatur materies crucibulo, et, adaptato operculo, urgeatur igne forti per horas sex. Materia bene trita immittatur aquæ bullientis libris sex in vase vitreo vel figulino, et agitatione permisceatur, aëris aditu, quanturn fieri possit, occluso. Stet vas in balneo vaporis, donec subsederit pars non soluta; dein effundatur liquor. Illi affundantur denuo aquæ bullientis libræ quatuor; quæ post agitationem et subsidentiam priori liquori addantur. Liquori adhuc calido, vel si friguerit iterum calefacto, instilletur acidum muriaticum, quamdiu moverit effervescentiam. Dein coletur, et vaporet ut crystalli formentur. 'SOLUTIO MURIATIS BARYTÆ. R. Muriatis barytæ partem unam, Aquæ destillatæ partes tres. 'Solve. SOLUTIO MURIATIS CALCIS. R. Carbonatis calcis puri (nempe, marmoris albi) in frusta con tusi uncias novem, Acidi muriatici uncias sexdecim, Aquæ uncias octo. Misce acidum cum aqua, et adde paulatim frusta carbonatis calcis. Effervescentia finitâ, digere per horam. Liquorem effunde, et per vaporationem ad siccitatem redige. Residuum solve ex sesquialtero pondere aquæ ; et demum cola.' P. 138. In the metallic preparations, as well as in the salts, the changes of the titles are numerous-the titles, themselves, circuitous and inconvenient. We cannot give even a slight account of the innovations in these respects, without too great an extent of our article. The first important change is in the preparation of emetic tartar. Instead of the pulvis algaroth, the oxidum antimonii cum sulphure per nitratum potassæ' is employed :-to put our readers out of pain, it is only the crocus antimonii. Three parts of the crocus with four of the crystals of tartar are to be boiled in a glass vessel, with thirty-two parts of distilled water, for a quarter of an hour; the strained liquor to remain till the salt crystallises. The aqua sapphirina is omitted. The carbonas ferri præcipitatus' is the ferrum præcipitatum, formed extemporaneously in Griffith's mixture, and very properly introduced. We shall add the formula, as well as that of the tinctura muriatis ferri, which is new. • CARBONAS FERRI PRÆCIPITATUS. R. Sulphatis ferri uncias quatuor, Carbonatis soda uncias quinque, Aquæ libras decem. Solve sulphatem ferri in aqua; dein adde carbonatem sodæ prius ex aquæ quantum satis sit solutum, et misce bene. Lavetur carbonas ferri, qui fundum petit, aquâ tepidâ, et postea siccetur.' P. 150. TINCTURA MURIATIS FERRI. R. Ferri oxidi nigri purificati et in pulverem triti uncias tres, Acidi muriatici uncias circiter decem, vel quantum sufficiat ad solvendum pulverem. Digere leni calore, et, soluto pulvere, adde 1 Alcoholis quantum sufficiat ut sint totius liquoris libræ duæ cum semisse.' P. 152. This method of purifying mercury, by filings of iron, was not formerly directed; and this purified quicksilver is usually employed. The formula for the acetis hydrargyri is somewhat corrected. The heat of the water, in which the acetite of potash is to be dissolved, is directed to be boiling; and all the vessels are ordered to be of glass. In the preparation of corrosive sublimate, the vitriolated iron is omitted. Two pounds of quicksilver are to be added to two pounds and a half of sulphuric acid (formerly four ounces of each), and the whole to be boiled till dry. This is to be added to four pounds of dry common salt (formerly five ounces), and the rest of the process proceeds in the usual way. In making the red precipitate- oxidum hydrargyri rubrum per acidum nitricum '-the proportion of the nitrous acid is increased. In the turpeth mineral, the proportion of sulphuric acid is reduced from eight to six ounces. We are sorry to see that inert useless preparation, the æthiops mineral, continued. It is now sulphuretum hydrargyri nigrum.' The formula for the solution of acetite of zinc we shall add. • SOLUTIO ACETITIS ZINCI. R. Sulphatis zinci drachmam unam, • Solve. R. Acetitis plumbi scrupulos quatuor, • Solve. Misceantur solutiones; quiescant paulisper; dein coletur liquor.' P. 163. The powders remain unchanged the electuaries are very slightly altered. The chief variation is substituting the syrup of ginger for honey, in the electarium opiatum. No very important alterations occur in the pills. The ghost of Plummer will certainly haunt the college; for his pills, strange to tell! are omitted. We believe no one more effectual preparation is retained. In the pilule aloëticæ, soap is employed instead of the extract of gentian; and, in the pil. hydrargyri, conserve of roses is directed instead of manna, and starch instead of liquorice-powder. In the pil. rhei C. the lixivia vitriolata is omitted. very convenient combination of asa-foetida and aloë, of each equal parts, is introduced under the title of pil. aloës cum assafœtida. A The troches remain unchanged. Among the ointments, we find new formulæ of the ung. oxidi hydrargyri cinerei, et rubri, and of ung acidi nitrosi, containing six drachms of the acid to a pound of axunge. The plasters have only the following addition. ́EMPLASTRUM MELOES VESICATORII COMPOSITUM. R. Resina pini laricis partes octodecim ; ' abietis, Meloës vesicatorii, utriusque partes duodecim ; Ceræ flavæ partes quatuor; Sub-acetitis cupri partes duas; Seminum sinapis albæ, Fructus piperis nigri, utriusque partem unam. Liquefactis primò resinæ pini abietis et ceræ adde resinam pini las ricis: his liquefactis, et adhuc fervidis, insperge cætera, in pulvereni tenuem trita, et commixta; assiduè agitans, ut fiat emplastrum.' . 200, . A table of doses, an index of new names with the old onesopposite, and in a contrary order, with a general index, follow.. On the whole, we consider this as a truly scientific and most valuable work. We have been teased with the new names, and think, on the whole, that other formulæ might have been added; but those which are introduced are select, clearly described, and admirably adapted. ART. III.-Philosophical Transactions of the Royal Society of London. For the Year 1802. Part. II. (Continued from page 26.) XV. ON the Composition of Emery. By Smithson Tennant, Esq. F. R.S.' Powder of emery is so useful in almost every art, where a hard body is required, either to give an edge to cutting instruments, or to cut glass itself-for what are called glazier's diamonds, or diamond pencils, consist of little more than an atom of emery--that we might have expected, in this age of inquiry, to have obtained more accurate information on the substance of which it consists. It was supposed to be an iron ore; but no iron could be extracted from it with advantage; and native iron, in any proportion, cou d not have been so hard. Our author, on examining it chemically, found it, in relation to different bodies, very similar to the diamond spar; and his further trials confirmed the affinity. The emery, most free from iron, contained, in one hundred parts, eighty of argillaceous earth, three of flint, four of iron, and three unaccounted for. The emery most impregnated with iron contained 0.32 of that metal. This is another instance in which the hardness of the mass does not depend on the ingredients. The atom of emery in a diamond pencil cannot contain a perceptible particle of flint; and the whole is harder than flint, and possesses nearly the hardness of the diamond. The latter could not be scratched by the former. All the emery which is used in England, is said to be brought from the islands of the Archipelago, and principally from Naxos. In those places, it is probably very abundant; as the price of it in London, which I was told was eight or ten shillings the hundred weight, appears little more than sufficient for the charges of carriage. Though I saw a very large quantity in one place. (more than a thousand hundred weight,) I could not find any pieces of a crystallized form; possibly the great proportion of iron usually mixed with it, may prevent its crystallization. The whole consisted of angular blocks incrusted with iron ore, sometimes of an octaedial form, with pyrites, and very often with mica. The latter frequently penetrates the whole substance of the mass, giving it, when broken, a silvery appearance, if seen in the direction in which the flat surfaces present themselves to the eye. As these substances have no chemical relation to the emery itself, it is remarkable that they should also accompany the diamond spar from China; for Mr. Klaproth observes, "that its lateral facets are mostly coated with a firmly-adhering crust of micaceous scales, of a silvery lustre :" he also mentions, besides felspar, pyrites, and grains of magnetic iron ore. P. 401. • XVI. Quelques Remarques sur la Chaleur, et sur l'Action des Corps qui l'interceptent.' Some Remarks on Heat, and on the Action of Bodies which intercept it. By P. Prevost, Professor of Philosophy at Ge neva. One great object of this author is an examination of Dr. Herschel's experiments, designed to estimate the quantity of light transmitted by different bodies, by which he appreciates the effects of a source of heat acting freely on one side, and passing through a coloured medium on the other. The law discovered by MM. Kraft and Richman is the foundation of our author's reasoning, viz. that, in a medium of a constant temperature, by which a body is warmed or cooled, the difference of its heat, compared with that of the medium, is in a geometrical progression, while the times of heating and cooling are in an arith metical. We cannot follow M. Prevost through his minute examination of Dr. Herschel's experiments, and his very ingenious calculations. In some instances, they agree exactly; in others, they differ from those of his predecessor, probably, at least in part, from the heat accumulated in the lamina through which the light is transmitted. A table of corrections is consequently added, in which it appears that the interception of the heat, calculated according to the foregoing law, is constantly less than the interception of light, of which it is a fraction which varies between one and seven tenths. M. Prevost next examines the source of the variations between the calculations and the experiments, and particularly between the experiments of Dr. Herschel and M. Pictet. Our author's explanations are supported by an experiment of M. Pictet, who found little heat reflected to the focus of a concave quicksilvered mirror, while, in the same situation, the focus of a metallic mirror was very much heated. In fact, the heat is reflected only from the coating; and consequently, passing twice through the thickness of the glass, almost the whole is lost. What then becomes of it? It contributes,' says M. Prevost, to heat the glass but is the glass hot? This should be ascertained; for we suspect that light only is lost. In these experiments, then, it is remarked, that the heat should, in the first instance, act, though feebly, as only a small portion which reached the lamina is transmitted. The plate is soon heated, and the thermometer is then exposed to a current of heat from it. When the heat has reach |