from the mother-liquors of sea water, which after precipitation of sulphates by chloride of barium and of calcium, and excess of barium by just, and only just sufficient carbonate of soda or of potash, furnishes at once a solution of chloride of magnesium, which may be used for production of the metal. It would even be possible to carry the concentration of the mother liquors of sea water just to that point at which they would contain the chlorides of magnesium and of sodium in suitable proportion to form the material in question. The presence of chloride of potassium in the mother liquors would be no disadvantage, neither would the presence of alkaline iodides and bromides be injurious. I do not recommend the employment of commercial magnesia as ordinarily sold as a source of the metal. The best samples of magnesia that I have been able to purchase contain a considerable quantity of sulphates, which I have not found it commercially practicable to separate. The most prolonged washing with boiling water is totally ineffectual in separating such sulphates. Nevertheless, commercial magnesia may be used, though not to advantage, for the production of magnesium, and in this case I proceed as follows:-The magnesia (or its carbonate) is taken up by undiluted or slightly diluted hydrochloric acid (free from sulphuric acid) of the usual strength, that is to say, of about 1152 sp. gr. slowly poured upon it, the acid being added very slightly in excess; chloride of barium is then added (in solution) in sufficient quantity to precipitate the sulphuric acid. After subsidence the liquor is decanted, and boiled upon bicarbonate of soda or of potash, added in sufficient quantity to neutralise the excess of acid and to precipitate the barium. Carbonate of seda or of potash may be used instead of the bicarbonates, but the latter are preferable, as their use is attended by less loss of magnesium, which always falls in considerable quantity with the barium. It is impossible by this method to completely separate the barium from the solution, but I have not found these traces of barium to in the least injure the product or purity of the magnesium obtained by a subsequent process. For a reason which will be given under, I avoid, whenever practicable, the use of ammoniacal salts in every stage of the preparation of the "material." After boiling the solution, as described, over the carbonate or bicarbonate of soda or of potash for about twenty minutes, and then filtering or decantation, it will be ready for the addition of chloride of sodium, and for the evaporation and ignition subsequently more particularly described. I, however, in all cases in which chloride of magnesium cannot be obtained from mother liquors of sea water, much prefer to make it from magnesia or carbonate of magnesia obtained as already described, and which process forms an important feature of my invention. To the magnesia thus obtained I add hydrochloric acid (free from sulphuric acid), in such proportions that a small quantity of magnesia shall remain undissolved. After boiling, the solution is filtered or decanted from the precipitate and portion remaining undissolved. I then add to the solution chloride of sodium in such quantity that for every pound of acid used of sp. gr. 1152 I use o 55 lbs. of chloride of sodium. I do not confine myself to this proportion, which is about that of equal atoms of the two salts, but greatly prefer it to any other proportion. When working mother liquors the chloride of sodium is employed in similar quantity. The chloride of sodium may be added to the concentrated solution of chloride of magnesium in the solid state, and evaporated to dryness, in, by preference, a 5 silver dish. This dried material is then placed in a platinum crucible, loosely covered, and heated to full redness. When it enters into tranquil fusion the operation is complete, and the fused mass may be poured out on to a clean cold iron plate, or it may become cold in the crucible, when it will fall out on inverting and shaking the crucible. The substance thus formed I call technically "material," and do not call it a double chloride, as I am doubtful as to its precise chemical constitution. This "material," if not immediately used, must be put into and kept in a perfectly dry vessel, which is secured against the access of moist air, as the material is slightly deliquescent, and a very little moisture represents the loss of a large quantity of magnesium in the subsequent process. If the material after being well fused in the platinum crucible, as described, be poured off, a portion which remains thick and is settled at the bottom, should be left in the crucible to be separately taken out and kept apart from the "material" if it be desired for the magnesium to be obtained as pure as possible. If the material be not poured out of the crucible, but allowed to cool within it, the mass will separate readily into two portions, one, the upper portion, a white and somewhat translucent mass; the other, the under portion, is of a greyish dark colour, and shows evidence of having been but imperfectly fused. When magnesia, prepared according to the process of precipitating Epsom salts, and of washing, as I have already described, has been used for the preparation of the "material," this dark portion is insignificant in quantity, and the same is the case when chloride of magnesium obtained from the mother liquor of sea water is employed, but when the magnesia of commerce has been used, even although purified as I direct, the proportion of dark matter is considerable. This dark matter is very similar to the dark matter obtained when chloride of magnesium is obtained by the method usually practised by chemists, namely, by evaporating and igniting a mixture of the solutions of chlorides of magnesium and of ammonium. The French chemists call it the carcasse, and regard it as consisting chicfly of magnesia formed by the decomposition of the water in the hydrated chloride during the process of ignition. This carcasse contains, however, besides magnesia, and intermixed chlorides, a peculiar substance, which is, so far as I know, as yet unrecognised by chemists. It simulates iron in many of its reactions. Like iron, its acid, peroxide, and perchloride solutions give a blue with solution of yellow prussiate of potash, but unlike in the case of iron this blue is unalterable, or changes only to purple when not quite pure on addition of ever so large an excess of ammonia. The lower oxide or chloride solution of the new element behaves also like iron in giving a blue with red prussiate of potash, which blue, however, unlike that from iron, is unchanged by excess of ammonia. Other reactions of the new substance are exceedingly like those of iron, but when its precipitate by an alkali is ignited it is reduced to a dark spongy mass before the blow-pipe on charcoal with very great difficulty. This mass does not fuse, and is not in the least magnetic. It is unnecessary to give further particulars respecting this element here, but it is necessary to point out that magnesium is always associated with this element, which has undoubtedly been hitherto mistaken for iron, however prepared, the new element may be separated by distillation of the magnesium, and besides this I know of no other effectual practical method. Even when only the white portion of material is used for the production of magnesium, the metal still contains * traces of the new element, which, for convenience of naming and provisionally, I call X. The material made when the magnesia made as I recommend is used is very much freer from X, as well as from sulphuric acid, than when the best magnesia of commerce is employed. I have put much stress upon the importance of separating sulphuric acid from the chloride of magnesium used in the preparation of the "material." It is equally important that the chloride of sodium used in the process should likewise be freed from sulphuric acid. I recommend for this purpose the following process:-Common salt as it occurs in commerce is dissolved in water. I prefer to use "condensed" water as constantly made where steam-engines are at work. The solution is treated with a sufficient quantity of solution of chloride of barium to precipitate all the sulphuric acid. The excess of barium is precipitated by carbonate of soda (I prefer to boil at this point) in excess of the barium to be precipitated. After filtration, or better, decantation from the precipitate, the solution is neutralised by hydrochloric acid free from sulphuric acid. I have not found the other foreign substances contained in common salt at all prejudicial, so that the solution thus obtained is fit for immediate use. The reason why sulphuric acid must be so carefully separated from the materials employed in the manufacture of magnesium is not because magnesium has a strong affinity for sulphur, which it decidedly has not, but because any sulphates present in the material are reduced to sulphides during the reaction with sodium. The oxygen thus liberated appears to divide itself between free sodium and nascent magnesium forming oxides with both. It thus happens that infusible magnesia is formed along with the reduced metal, and effectually prevents the latter fusing together so as to form in lumps. If more than mere traces of sulphates be present in the material from which magnesium is reduced, it will usually be found that the metal is dispersed in very minute powder or globules throughout the mass, whereas, if the material be free from sulphates, and otherwise properly prepared according to the directions given above, the reduced magnesium runs, at least in part, into globules of considerable size. With respect to the running of the metal together in globules or lumps, it remains to be observed that the freer the "material" is from X, the more completely does this happen. As already stated, I prefer to use no ammoniacal salts in the course of the preparation of the material from which the magnesium is ultimately obtained. I would add, that no substance containing nitrogen should be used. Magnesium exhibits even in its compounds a powerful affinity for nitrogen compounds, so that I do not think it can be on a practical scale completely freed even from ammoniacal salts by howsoever prolonged ignition. A large portion of magnesia is carried away perhaps partly mechanically, but certainly partly in chemical combination when magnesia or chloride of magnesium is ignited with chloride of ammonium. Nor can the remaining chloride of magnesium be obtained so free from ammonium as not to afford traces of the usual ammoniacal precipitate when its solution is tested with the bichloride of platinum. But when the material from which magnesium is to be obtained contains ammonium, in whatever state of combination, the magnesium obtained from it invariably contains nitrogen, the presence of which causes the magnesium to have a yellowish colour, and to tarnish rapidly in the atmosphere. In order to obtain magnesium from the "material," I place the latter with sodium in an iron crucible or vessel closed with an iron cover, and heat to full redness. The cover should not be removed from the crucible until the crucible is nearly cold. The mass within the crucible may usually be shaken out, or, if necessary, it may be washed out by water. The salts contained in the mass may be washed away by water, when magnesium, more or less pure and conglomerate, according to the purity or impurity of the "material" used, remains. The washing should be effected as rapidly as may be, especially when impure material has been used. The magnesium should be immediately dried by a gentle heat not much exceeding 100° centigrade. If inclining to be pulverulent, the magnesium should not be heaped up while moist, but should be spread out thinly, and rapidly dried, otherwise, if in quantity, it might heat strongly, or perhaps ignite. This remark applies to impure or badly prepared magnesium. I recommend moist pulverulent magnesium be placed upon bibulous paper or porous slab, or some other substance capable of quickly absorbing moisture, before it is dried by heat. The proportion of sodium to material that I prefer to employ is about one part of the former to five of the latter; but the proportion of sodium may be slightly increased or considerably diminished. If much increased the excess of sodium burns explosively when the cold fused mass is washed with water, if much less be used the yield of magnesium is diminished. When the carcasse already described is used as part of the material, rather more sodium may be employed, also if the material has been so strongly ignited during its preparation as to have volatilised away any considerable quantity of chloride of sodium, I find the best result to be obtained when the material is placed in the crucible coarsely powdered. There should be a layer of the material at the bottom of the crucible, then the greater part of the sodium in large pieces, and then the crucible should be filled up with the remainder of the sodium in smaller pieces, and with the rest of the "material." The crucible should be perfectly free from rust, and the cover should have an inside flange so as to fit closely, but it need not be fastened down. The crucible should be quickly heated up to, but not beyond full redness. If the heat be raised too high, magnesium vapour forces its way beside the cover, and burns brilliantly in the air. It is not necessary nor desirable that the heat should be continued for more than about half an hour after the whole crucible with its cover has become red hot. I have never found the iron vessel in which the reaction is effected to be at all acted upon interiorly when the cover fitted properly, and did not become shifted during the process; if, however, through bad management, air gain admittance, the iron becomes attacked so far, and and so far only, as air has penetrated. I never found the magnesium formed in iron vessels to have taken up any trace of iron from the vessel unless in case of access of air, or when the heat has been excessively elevated. With moderate care, no such accident can well happen. The same iron vessel may be used repeatedly, time after time, without particular cleaning, if no water or moist air be permitted access during the intervals of the using. The magnesium formed by the foregoing process I purify by fusion in anhydrous chloride of magnesium, which for this purpose I prefer to employ without admixture with any other kind of flux. When the magnesium is pulverulent it may (if previously made perfectly dry) be thrown into a small quantity of chloride of magnesium already fused in a crucible. The crucible 7 dry hydrogen gas. If coal gas be employed, it should be freed from sulphuretted hydrogen, ammonia, air, and moisture. Dry hydrochloric acid gas may be passed over fused magnesium without the latter taking fire, and the metal, if impure, becomes purer by the process. The specific gravity of magnesium is about 174. cover must be instantly put on, and the heat continued be fused into solid masses in iron vessels, from which the for a few minutes, more or less, according to the quan-air is excluded by coal gas, or, as is more convenient, by tity operated upon. The cover is then quickly removed, and the mass is compressed by a rather large and perfectly dry and clean iron rod. As the chloride of magnesium begins to solidify (the heat meanwhile being diminished), the metal may be compressed into globules, which may usually be run together. The magnesium rarely takes fire, but should this happen it is only necessary instantly to adapt the cover. When cold, the lump magnesium may be washed with dilute acetic or nitric acid, and then thoroughly with water. The surface of the metal is thus brightened; but if the washing acid contain iron, the latter is instantly precipitated upon the surface of the magnesium, and blackens it. I prepare anhydrous chloride of magnesium by slowly heating the hydrated chloride to redness in a current of dry hydrochloric acid. I use, by preference, a platinum crucible, into the cover of which two tubes are fitted, one for the ingress and the other for the egress of the stream of hydrochloric acid gas. I find the following to be a convenient arrangement:-A flask or other suitable vessel containing strong sulphuric acid has an acid tube passing through its closely fitting cork or stopper; the lower end of the tube enters the sulphuric acid. A tube connects this flask with another vessel containing sulphuric acid for drying the hydrochloric acid gas. This vessel is provided with a safety tube, and with a tube which connects this vessel with the ingress tube of the platinum crucible. The arrangement for the extrication and drying is precisely that in constant use in laboratories. All being prepared, the crucible being charged with chloride of magnesiam, previously dried at a temperature not exceeding 130° centigrade, heat from a gas flame or otherwise is caused to play upon the crucible, and pure hydrochloric acid is slowly poured through the acid tube into the flask containing sulphuric acid. Hydrochloric acid gas is rapidly extricated, and, passing over the heated chloride of magnesium contained in the crucible, carries off the moisture and escapes through the exit tube. The process of dehydrating the chloride of magnesium is soon accomplished, the conclusion of the process being known by the crucible attaining a full red heat when a sufficient source of heat is used. The crucible may be allowed to cool, and the chloride of magnesium be then dropped out, or it may be poured off on to a cold, clean, and dry iron plate while the chloride is yet fluid. The hydrochloric acid gas passing out of the crucible by the egress tube may readily be condensed by the attachment of a tube connecting the egress tube of the crucible with a little water. After condensation the hydrochloric acid may of course be used over again, as may also the sulphuric acid if it be first concentrated by the evaporation of the water which it has imbibed during the process. Magnesium prepared by the preceding process has a silver-white colour, is very brilliant, malleable at a temperature below redness, but somewhat brittle at common temperatures. It fuses at a red heat, and at that temperature burns in the air, giving a brilliant white light. It is but little oxidisable at common temperatures even in moist air, and is not sensibly affected by sulphuretted gases; it is acted upon by ammoniacal gases. It cannot easily be cast in air, as it is very viscous at a temperature but just above its fusing point, and at the temperature at which it flows readily it inevitably takes fire. It may, however, be fused in chloride of magnesium, upon the surface of which it floats, and then be drawn up into tubes by suction, and so obtained in ingots. It may also Picture Chemistry, by THOMAS SALTER, F. C.S. A PICTURE is an attempt to represent, on a flat surface, the forms and hues of nature, whether animate or inanimate, human or otherwise. As such, a picture is called a work of art; the more rightly, the nearer it approaches nature, the more correctly and vividly it brings before our eyes the varied scenes and moods of creation, or the customs and passions of mankind. But a picture is not merely a work of art, it is also a work of science. A modern painting is the joint produce of the studio and the laboratory, and it is to chemistry that Art owes so many colours, brilliant and unfading as herself. Pigments belonging to bygone times it is not my intention specially to notice, but rather to glance at a few of those at present in use, whether ancient or modern, noting briefly their composition, together with, from the scientific point of view, their virtues or failings. And here it may be as well to admit that the palette is not yet perfect, containing as it does too many weeds, which ought long ago to have been rooted up, but which never will be rooted up until artists possess a greater knowledge of the chemical properties of colours. The day has surely arrived when the head and the hand should work together, when theory should join practice to produce a more perfect and a more lasting result. For it is not because pigments are placed upon canvas or paper, that they necessarily remain there, a durable record of the painter's skill. Many changes they may be liable to, not alone from air, light, time, and foul gases, but from the vehicles, varnishes, &c., with which they are treated, and from reaction up on each other. Not unoften, indeed, a picture makes, as it were, a very pretty series of experiments with its colours, causing some to combine with others, some to deepen, some to pale, some to vanish altogether, until the labour of weeks, months, may be of years, becomes slowly but surely converted into a chaotic blotch. To banish, then, such chameleon paintings, chameleon pigments must be banished likewise, by our knights of the brush having a certain acquaintance with chemistry. May the hope be expressed that at no very distant period a School of Art worthy of the name will be formed, of which a lahoratory will be a distinctive feature? There the young student could learn and see why and how colours were trustworthy or treacherous, under what conditions some were apt to change, and what those changes were, could test the merits of new pigments, and obtain a knowledge which some of our R.A.'s even would be none the worse for. But to enter more particularly into the subject of my paper. Colours, artist colours, may be classed as inorganic and organic, and may be described as being either permanent or fugitive, transparent or opaque. Their transparency or opacity, however, being more strictly artistic qualities, will not, except in the case of new claimants for palette fame, be remarked upon. is their duo, those pigments shall have precedence which As are permanent, whether obtained from metals and earths, or from the vegetable and animal worlds. PERMANENT PIGMENTS. Inorganic Yellows. Aureolin.-There has, until within the last year or two, been wanting a yellow at once permanent, transparent, brilliant, and pure in tint. This void aureolin fills. The preparation being a trade secret, I shall not in courtesy enter into its composition, or attempt to describe a means of producing it. Suffice it to say that the colour is extremely beautiful, and, to my knowledge, is quite uninjured by air, light, time-that great enemy of artists-sulphuretted hydrogen, or by admixture with other pigments. Cadmium Yellows are obtained from cadmium and sulphur. Being sulphides, they are not affected by impure air, and the deep gorgeous varieties may in other respects be safely relied upon. Those of a pale lemon hue should be regarded with suspicion. There were several samples of that tint shown at the International Exhibition both by foreign and British colour makers, but all, without exception, became (I noticed) gradually coated with white. Lemon Yellow, produced from barium and chromium, when skilfully prepared, is a safe, reliable colour. Unlike chromates in general, it is not sensibly altered either by light or a foul atmosphere. Mars Yellow is an artificially prepared ochre, of which the chief constituents are iron, silica, and alumina. When pure it is a most stable pigment, of a clear, sober, gravel tint. Except with respect to colour, the same remarks are applicable to the native iron earths, such as yellow ochre, Roman ochre, &c. Organic Yellow. Cyanogen Yellow, in the preparation of which, as its name denotes, cyanogen in some form or other is employed, was one of the many new pigments first introduced to the public by Messrs. Winsor and Newton at the last Exhibition. Of a gorgeously golden hue, it may claim to be our only permanent organic yellow. Less opaque than the cadmiums, it is quite as durable, and equally unaffected by sulphuretted hydrogen. Inorganic Reds. Indian Red is a dark peroxide of iron, of a purplerusset hue, brought, it is said, from Bengal. This nature-furnished pigment is but little altered either by light, time, impure air, or mixture. Light Red, Venetian Red, &c., are iron ochres, either native or artificially prepared. Clear, though not bright in tint, they are most stable colours. Vermilion, composed of mercury and sulphur, is the only brilliant inorganic red (iodide of mercury excepted) at present known, and the only permanent scarlet which the art world possesses. If true, neither exposure or a foul atmosphere sensibly affect it. , NEWS PHYSICAL SCIENCE. 1863 An Improved Spectroscope.-Analysis of the Fixed Line D, by Professor JOSIAH P. COOKE, Jun. (Extracted, by permission, from a letter to Dr. Percy.). I HAVE had a spectroscope constructed, which I believe to be the largest and most powerful ever yet applied to the spectrum. It has nine prisms, filled with CS,, giving 2 inches aperture, with telescopes of corresponding size. By means of a conical wheel, against which the backs of the prisms rest, I am able to adjust them with great facility to the angle of least deviation. Two pins on the back of the prism are so adjusted that, when pushed against the wheel, the back of the prism is tangent to the circle. By means of this simple contrivance I can make the adjustment from one end of the spectrum to the other in a very short time. The prisms are constructed on a plan suggested by my friend Professor Rood. They have wide frames with levelling screws. To the faces pieces of the best plate glass are cemented with a mixture of glue and honey. Outside of these other plates are applied whose outer surfaces have been most carefully ground plain, with castor-oil between. This gives a very perfect prism. As the light is here bent through almost 360°, we have reached about the limit of power, unless we can reflect back the rays over the same path. This instrument has established the following points: 1st, That the lines of the solar spectrum are as innumerable as the stars of heaven. It shows distinctly at least ten times as many lines as are given by Kirchhoff in his chart, and an infinitude of nebulous bands just on the point of being resolved. To give you an idea, I enclose a drawing of the D line of Fraunhofer as seen by it. Kirchhoff only gives three lines-the two broad ones and a faint central one. You notice there are six others and a nebulous band. 2nd. It proves that the coincidences between the Red end. Violet end. bright lines of the metallic spectra and the dark lines of the solar spectrum remain perfect even with this greatly of the sodium line so far apart that I can readily disincreased power, I am able to spread the two members tinguish of the intermediate space, and yet the coincidence with the two dark Fraunhofer lines is still absolute. At the sitting on the 8th of last month, Dr. Hofmann made the communication we have printed in another part. Dr. Hofmann's discovery will no doubt lead to important results in the manufacture of the so-called aniline colours. In a paper entitled "New Researches on the Preservation of Building Materials," M. Kuhlmann announced to the Academy his discovery that coal tar pitch was useful in protecting materials from the action of moisture, and preventing their decay. We believe this has been known some time in England. M. Kuhlmann has also found a new use for burnt pyrites, which, he says, made into a mass with a-quarter of its weight of coal-tar pitch, forms, when cold, a material of remarkable hardness and sonoreity. He states, too, that when hot pitch is applied to plaster, it drives out some of the water of hydration, and penetrates some distance into that porous material. The author thinks that pitch will effectually preserve the exterior decorations of buildings from the action of water and the consequences of frosts,-which we are as willing to believe as that the appearance of the building would not be at all improved by the application. M. Scheurer-Kestner continues his memoir on "Some New Compounds of Iron, and on the Atomicity of this Metal." His researches display great ingenuity, as our readers will see by his account of the Formio-aceto-ferric nitrate,red crystals obtained either by acting on ferric hydrate by proper proportions of formic, acetic, and nitric acids, or by oxydising a mixture of equivalent amounts of ferrous acetate and formiate by means of nitric acid. There is at first obtained a red solution containing a salt with two molecules of nitrile : which represents the diformio-diaceto-ferric nitrate. M. Hugo Schiff, having in previous memoirs made known the fact that the mono- and diatomic metals will form anilo-metallic compounds, has now extended his researches to the triatomic metals, and has found that they furnish analogous compounds. These may be formed by the direct addition of aniline to a solution of the different salts in benzol. Three equivalents of aniline, for instance, will combine with one equivalent of anhydrous chloride of antimony, forming, after some hours, a white crystalline mass, which is hydrochlorate of stibanile : At the sitting on the 15th of June, a paper by Dr. Hofmann "On Hydrazobenzole, a new Compound Isomeric with Benzidine," was read. This paper we shall give to our readers in full. An extract from a letter from M. Schönbein to M. Dumas was read, in which the writer promises at an early date an extended memoir "On the Catalytic Activity in Organic Substances." According to M. Schönbein, catalysant substances are widely diffused in both plants and animals, but it would appear that the memoir will be devoted to those concerned in the phenomena of germination. M. Barral contributed an important "Note on Bread Crust and Gluten." The author has established that the part of bread crust soluble in water contains from 7 to 8 per cent. of nitrogen; while the soluble part of bread crumb only contains from 2 to 3 per cent. The former therefore, M. Barral says, is more nitrogenised than the juice of meat. He concludes that gluten exposed to a temperature of 200° or 220° C. undergoes some transformation and becomes soluble in water. An experiment proved that gluten heated to 220° in a sealed tube became liquid and evolved carbonic acid. The liquid was sensibly alkaline, and had a peculiar odour. M. Fordos continues his "researches on pyocyanine blue pus," of which we have given notices. From pyocyanine he has now separated a yellow matter, which he calls pyoxanthose. The author gave the means by which he obtained these matters from stained linen and separated them, but we have not space for his methods. He described both as definite crystalline compounds, easily distinguished from other blue and yellow matters in animal secretions, but does not give us the composition. munication by M. Berthelot, "On the Action of Acids on Diluted Alcohol," establishes the fact that the quantity of ether formed is the smallest when there is excess of neither acid nor alcohol. A paper, "On the Decomposition of Water by Sulphur," by Mr. Gripon, will be given in a future Number. NOTICES OF BOOKS. A com The Pharmacopoeias of Thirteen of the London Hospitals. Arranged in Groups for easy Reference and Comparison. By PETER SQUIRE, F.L.S., &c. Churchill and Sons, London. 1863. THIS well-devised book has been issued at a very inopportune time. The pharmacopoeias of several London hospitals, we believe, are out of print, and are not likely to be reprinted until after the publication of the British Pharmacopoeia, which will of course necessitate the reconstruction of all of them. Mr. Squire would therefore have given his book a more enduring interest if he had deferred its compilation for a time. As it is, it is likely to be out of date in the course of the next six months. The object of a hospital pharmacopoeia, as most of our readers know, is to save prescribers the trouble of writing long prescriptions, and to enable the dispensers to keep a number of commonly-used medicines ready compounded, which they would otherwise have to mix at the time. Occasionally they are found to supply cheap substitutes Our readers will see, therefore, for expensive remedies. that the interest of them is mainly confined to the institution for which are they compiled. They serve, however, for general practitioners, who can adapt for their own surgeries the formula they have seen in use in the hospitals at which they have been educated. Nevertheless, they are of some interest to the general pharmaceutist; and we have heard a druggist remark that the possession of a pharmacopoeia of one special hospital was worth two hundred a-year to him, by enabling him to dispense prescriptions which, without the pharmacopoeia, would have been unintelligible. Some of the formulæ in these pharmacopoeias have a strange look to modern eyes. At Guy's Hospital they still retain the use of the old word julep. At the Westminster they have a "Lac cum sevo,' a compound they also prescribe at Guy's under the name of "Mistura sevi" -a valuable remedy, no doubt, but one which we fancied had long been abandoned to the use of old women. At the London Hospital they call the cough linctus by the old word "lohoch;" and altogether, at the larger hospitals, pharmacy seems to be rather behind the age. Of the general arrangement of Mr. Squire's book, and of the accuracy of the translations, we can speak very well; but we do not see why he should print the same mixture as Mistura Ferri Muriaticum and Mistura Ferri Sesquichlo |