I have followed herein a uniform system of halving the types given by Dr. Odling, but by no means contend that such is necessarily or in all cases correct. Bloxam very reasonably contends that the green salt of Magnus, H3PtN.Cl, should rather be H5Pt2N2C1+ HCl (or, as in my list, H6PtN2, C1+PtCl), that is, a hydrate rather than a chloride. In this, as in many cases, the probability is great that both forms subsist in analogous cases. It is most improbable that all platinum substitutions (as in my list) should be mono substitutions; and it is still more improbable that all the series should contain two atoms of Pt, as in Dr. Odling's list. The truth, in all probability, lies between the two extremes; but the pity is, that, while valid bases of discrimination subsist, the matter should be left to the empiricism of individual preference and merely numerical analogies. Platinum forms no exception to the general facts of substitutional interchange and variation, and the alleged distinctions between mono-, bi-, and tri-atomic elements of substitution may possibly prove to be as fanciful as they are elaborately and ingeniously pourtrayed. If we instance the radicals of biatomic glycol, or triatomic glycerine, we find that both derived acids are admittedly monatomic. And, what is far more to the point, both are derived by an identical process to that which gives acetic acid from alcohol; and, as the latter gives either ethylamine or acetamide, so the former give their corresponding amines or amides Ethylamine (C,H5)H2.N. Acetamide (C4H3O2)H2.N. Glycolamine (CHO2) H2.N. Glycolamide (CH3O4) H2.N. Glyceramine (CH-04)H2.N. Glyceramide (C6H5O6) H2.N. And similarly in corresponding sulpho-acids and other derived and substitutional forms. But, in regard to the platinum case in question, the radicals of carbonic and Oxalic acid have a closer bearing on the subject. With these we have Let copper replace (CO), and we have another homologous series, where Cu(315) and Cu(63) equally replace one atom of H to the production of similarly-varied types. The remarks of Dr. Odling on the platosamine group exceedingly cogent and well put. are very varied and interesting, and, in an eclectic sense, I also believe in "the parallelism in constitution and properties of the two compounds, and of their corresponding hydrates," and, still further, that neither contains any diatomic element per se, or replacement of 2H; but I say nothing of ethylenamine in this connection, being engaged on an extended study of the diatomic hypothesis. AMO-PLATOSAMINE. What these are may be seen by a glance at either scheme of notation; they are simple repetitions of the preceding with H3N superadded-in fact, they are doublycondensed ammonias, or, as we have called them, atmonias. PLATINAMINE COMPOUNDS. In all these, the mode of preparation is instructive; they are forced conditions under the influence of nitric acid or permanganate; and hence the resulting binoxide or bichloride forms of the preceding types, which is especially manifested by the tendency to bi- and sesquisaltic types so common in such cases. It is curious to observe that the three cases selected from Raewsky are, with one little variation in the third instance, precisely double those of the first three of M. Gros's series. In conclusion, I have merely to observe that this paper has no pretension to any adequate review of the proposed scheme of Dr. Odling, which has the great merit of associating chemical with other considerations, and well deserves a higher tribuna ON SOLUTIONS: HISTORICAL NOTE. By CHARLES TOMLINSON, F.R.S. Those who take any interest in studying the history of science must have felt some surprise at seeing Swedenborg's claim to what has been considered as an important modern discovery in Physics advanced in Prof. Beswick's interesting paper in a recent number of the CHEMICAL NEWS (vol. xxii., p. 25). {CHEMICAL NEWS, July 29, 1870. first edition of his Physics in 1726, and the second in 1734, an English translation of which was published by Colson in 1744. I have not had an opportunity of examining the original, but in the translation, p. 252, the following passage occurs: "If fluids are composed of spherical or spheroidal corpuscles, they must leave many interstices between them, into which lesser parts can insinuate without the intumescence of the whole mass. Hence salt dissolved in water fills up the interstices, which will be done still more accurately if sugar be then Swedenborg's reputed discovery that in the solution, added, and more still by the further addition of alum." If by intumescence is meant "increase in bulk," we say, of a salt in water "the saline particle in the water have the fact familiarly announced by a well-known indoes not increase the space, but only occupies the void;"vestigator in physics in that unconscious manner in which or, in other words, "the mere particles of salt cannot at an old and admitted fact is handled. Moreover, in the all add to the bulk, but only to the weight, because they early part of this treatise there is a good deal of interestoccupy the spaces between the aqueous particles," is not, ing speculation about the shapes of the porous spaces, I am inclined to think, so Swedenborgian a proposition as and calculations as to their magnitudes. Prof. Beswick supposes. I do not mean to say that earlier writers announced the fact in the same words, but the fact followed, I think, naturally from the theoretical teaching of the previous century. For example, Descartes (born 1596-died 1650) illustrates the porosity of matter by supposing a number of apples or of bullets, very smooth and round, to be tied up in a net so as to form a compact solid. Whichever way you turn this solid and throw upon it small shot or any similar sphericules, they will pass completely through this body by their weight. Gassendi (born 1592-died 1655), whom Bayle describes as "the greatest philosopher among scholars and the greatest scholar among philosophers," adopts a similar figure to illustrate the porosity of water. He supposes a bushel measure to be filled with wheat; there must then be between the grains certain small spaces void of grains: so among the corpuscles of water or of air, there must be small spaces which, not being filled either with water or air nor with any other body, are absolutely void. In another place he speaks of silver dissolved by aquafortis and diffused through its little pores. But the most remarkable passage bearing on the point in hand that I have met with in this very suggestive writer is the following:-"I have long known," he says, "that water can dissolve a certain quantity only of salt, and being once saturated with it the rest remains undissolved. Hence it occurred to me that, the salt being thus reduced to very small particles, there must exist in the water certain small spaces capable of receiving them, which spaces being filled up, solution ceases. It further occurred to me that the corpuscles of salt being cubical might really fill up small spaces which were also cubical. But since the same water could not only dissolve common salt, but also alum, which has an octahedral figure, but also nitre, sal-ammoniac, sugar, and other bodies, which have all different figures, there must, then, also exist in the water octahedral, &c., spaces, so that water being saturated with one of these salts is not prevented from dissolving the others. In effect, my conjecture was right; for having thrown a morsel of alum into water which some days before had been impregnated with common salt, it was dissolved just as if there had been no common salt present; and not only alum, but some other salts that I threw in were dissolved; from which I concluded that there must exist in water a number of insensible spaces of different figures; and I now understood how it was that water saturated with tinctures of rhubarb or of senna or matters ordinarily obtained by infusion is not so saturated with one as to be incapable of taking up another,"-(Vol. iii., p. 182'). It seems to me to follow, from the passage italicised in the above quotation, that the salt with which water is saturated (to use the words of Swedenborg once more), "does not increase the space, but only occupies the void." Musschenbroek (born 1692-died 1761) published the * I quote from the "Abregé de la Philosophie de Gassendi," en vii. tomes, par F. Bernier: Lyon, 1684. There is a copy in the Library of the Royal Society "Presented by the Author, An° 1685." The original Latin of the passage quoted is in Gas. Phys., 1. i., sec. i., cap. ii. In another once well-known treatise by Clare, "On the Motion of Fluids,"* the well-worn metaphor is used in which water is represented by bullets in a barrel, the interstices between the bullets will contain a great many small shot, "the vacuities of the shot may then be replenished with a certain quantity of sea sand, the interstices of the grains of sand may again be filled with water, and thus may the weight of the barrel be greatly augmented, without increasing the general quantity.t Now this being true with regard to solids is applicable also to fluids. For instance, river water will dissolve a certain quantity of salt, after which it will receive a certain quantity of sugar, and after that a certain quantity of allom, and perhaps other dissoluble bodies, and not increase its first dimensions." Such is the teaching of all the treatises I have seen about the time when Swedenborg is said to have announced his discovery. It seems to me that the teaching was adopted from Gassendi, which, being nearly a century old, was taken so much as a matter of fact as not to require the special notice it would certainly have met with had it been first pointed out by Swedenborg in 1721-2. Mr. Beswick supposes that, between the date of Swedenborg's book and Dalton's essay, in 1840, the important fact in question remained unknown, and consequently fruitless. We have already seen that it was not unknown; we have now to show that it was taken up as a good working suggestive fact. In the memoirs of the Royal Academy of Sciences of Berlin for the year 1750 is a long paper, by Eller, in which are described a number of experiments for determining exactly the quantity of each kind of salt which conceals itself in the water (qui se cache dans l'eau) without augmenting the volume, or the vessel in which the operation is conducted becoming fuller. A glass globe of 8 ounces' capacity, with a tube fitted to the neck 10 or 12 inches in length, and 3 lines in internal diameter, was filled, for each observation, with distilled water up to a mark half way up the stem. Each kind of salt was purified and reduced to powder, the temperature being taken in degrees of Réaumur. The 8 ounces of water dissolved the following quantities of the substances named, without any increase in bulk: All the reasoning in this paper is evidently derived from Gassendi; for example, Mr. Eller says-" No one doubts the porosity of matter; and the preceding phenomena also prove, I think, the existence of interstices among the spherical bullets (boules) which form the ultimate elements of the water. I shall not decide whether these pores are triangular, square, pentagonal, or polygonal, so as to assist or refuse entrance to the molecules of the salts which are of different figures. Water, by its intrinsic motion, separates and divides the salt into invisible atoms, probably as small as those of the water, so that they are adapted to thread the pores of the water and become equally distributed among its mass, which holds them suspended and floating by its interior movements, notwithstanding their excess of weight. But the pores of the water being, probably, different among themselves, as the molecules of different salts are, it follows that the homogeneous molecules of one kind of salt can fill only those pores of the water that are adapted to it, while the same water can receive other molecules, whose figures are different from those of the first." Thus, 8 ounces of water saturated with 91 ounces of green vitriol (at 11° or 12° R.) can still dissolve 1 ounces of Seidlitz, 2 drachms of refined saltpetre, and 3 ounces of refined sugar; or, the water that has dissolved 2 ounces of alum can also dissolve 6 drachms of common salt and I drachm of Epsom salt. Mr. Eller also points out (page 92) that mercury will dissolve certain metals without any increase in bulk. In the Philosophical Transactions of the Royal Society for 1770 is a paper by Dr. (afterwards Bishop) Watson, "On the Phenomena Attending the Solution of Salts," from which it appears that the writer failed in attempting to repeat Mr. Eller's experiments. I have no doubt that, with a little more research, other papers might be found bearing on the point in question. At any rate, it seems scarcely justifiable that so eminent a man as Dalton should, so late as 1840, suppose himself to be the discoverer of these facts, and refer to them as "the greatest discovery I know of next to the atomic theory." Scientific workers and scientific historians form two distinct classes, and the former do not hold the latter in much esteem. player is seldom or never a good problem composer, In the same way, a first-rate chess as the latter is never the former, he is placed on a low and chess level by the Philidors of the clubs. I ought, perhaps, to add, by way of caution to the student, that the observations of facts above quoted may require a good many errata; these are supplied by Messrs. Playfair and Joule (Phil. Mag., xxvii., 1845). Highgate, N., July 1st, 1870. ON THE ANILINE OR COAL-TAR COLOURS.* COMMERCIAL magenta consists of brilliant crystals, sometimes half-an-inch in length, having a beautiful goldengreen metallic appearance; these dissolve in warm water almost entirely, forming an intense purplish red solution. Dr. Hofmann has carefully studied the chemical nature of magenta, and has found it to consist of the salt of an organic base, which he has called rosaniline. This base may be obtained from the commercial product, by dissolving it in water and boiling it with an alkali, or alkaline earth such as ammonia, potash, or lime; it is thus rendered nearly colourless, and after filtration rosaniline separates from the clear solution, on cooling, in colourless crystals. It is composed of carbon, hydrogen, and nitrogen when anhydrous, but generally contains an equivalent of water also. The anhydrous base has the formula C20H19N3. The Cantor lectures, delivered before the Society of Arts. 53 upon combining with an acid, as I can show you by heating some with acetic acid, when the colour is imThis colourless base immediately becomes dark red mediately developed. The magenta produced by heating commercial aniline with nitrate of mercury is the nitrate of rosaniline; that produced with arsenic acid is the arseniate, but in the process of purification this latter salt becomes converted into hydrochlorate, which is the salt most generally found in the market. Other salts are also commercially manufactured, such as the oxalate and these salts are generally prepared from pure rosaniline, by combining it with the required acid, and crystallising from acetate, especially when a very pure product is required; water. octahedra, possessing the ordinary golden-green metallic reducing agents it became colourless, or nearly so, but This base, when brought in contact with hydrocyanic acid, tained, commercially called phosphine. This substance In the formation of magenta, a second product is obhas investigated it, and found it also to contain an organic was first introduced by Mr. E. Nicholson. Dr. Hofmann base, which he has called chrysaniline. Phosphine or chrysaniline is not capable of being produced at will, and the quantity formed in the manufacture of magenta is variable. In shade it is of rather a yellow orange. This colouring matter differs from rosaniline, the base of magenta, in exactly the opposite direction to leucaniline, containing two atoms less of hydrogen. Leucaniline, rosaniline, and chrysaniline, are thus related : Leucaniline C20H21N3 scarlet with magenta. It is not converted into magenta, Girard and Delaire, but, I am sorry to say, my time will 54 On the Aniline or Coal-Tar Colours. We will next consider some of the derivatives of magenta, and the first we will study is aniline blue or bleu de Lyon. If aniline be treated with a salt of rosaniline or magenta, a remarkable change takes place; at first the colour gradually becomes purple, but afterwards gets quite blue, ammonia being evolved at the same time. This peculiar reaction was observed by MM. Girard and Delaire, who found that that this change of colour was due to the formation of a new body, which they termed the bleu de Lyon; intermediate products were likewise obtained, to which we shall refer presently. MM. Girard and Delaire patented their process in January, 1861. This new aniline blue is one of the most important of the artificial colouring matters, and its manufacture has been very much improved upon since its discovery. There are several circumstances which materially influence the beauty of its tint, such as the quality of the aniline and {CHEMICAL NEW, July 1870. the particular salt of rosaniline employed in its manufacture. It is found by experience that the aniline should be as pure and free from toluidine as possible, and that the salt of rosaniline should contain a feeble acid, such as the acetate, valerate, oleate, or benzoate; but why the latter is necessary chemists are unable to understand at present. Practically, the various salts of rosaniline required for the manufacture of the blue are not prepared separately, but are produced in the operation by double decomposition, which is simply a process of exchange; thus, if acetate of rosaniline is required, a mixture of hydrochlorate of rosaniline and acetate of sodium is employed; these react on each other, and change into acetate of rosaniline and chloride of sodium. On the large scale, the process of making aniline blue is carried out in various ways, but many employ the apparatus shown in fig. 6. This apparatus consists of an oil bath, a, set in a brick furnace; it has a cover, b, perforated with large holes; into these holes are placed small enamelled cast-iron pots, c, provided with a flange, on which they rest. These pots will hold from three to five gallons, and are fitted with lids held down with clamps; each lid is provided with a small stuffing-box, through which the rod of a stirrer, d, passes. In the lid are also two other perforations; one of these is fitted with a wooden plug, e, for the purpose of testing the progress of the operation; the other is connected with a bent, movable tube, f, united to a long central main, to collect any aniline vapour which passes over. This main is connected at one end with a worm, g, to condense the vapours. The oil bath by which these pots are heated is provided with a thermometer, so that the temperature may be properly regulated. In preparing the blue a mixture of magenta, acetate of sodium and aniline is introduced into the pots, the aniline being employed in excess. When charged, the oil-bath is heated up to 190° C., and kept near that temperature. At first the red colour of the mixture changes slowly, but afterwards with rapidity. The progress of the operation is ascertained by removing the wooden plug, and withdrawing a small quantity of the product upon the end of an iron or glass rod, and it is considered complete when a good blue colour has been obtained; to ascertain this point with precision, considerable experience is necessary. The excess of aniline distils during this operation, and is condensed by the worm, and collected into a suitable receiver, so that it may be used again. From the crude blue product thus obtained, which is a fluid of the consistency of treacle, all the different qualities of blues found in the market are prepared. The cheaper qualities are obtained by simply treating the crude product several times with hydrochloric acid. This removes all the free aniline, and most of the red and purple impurities. Another similar but more effective process is employed for the preparation of the better qualities, and consists in mixing the crude product with methylated spirits of wine, and pouring it into water acidulated with hydrochloric acid, and then thoroughly washing the colouring matter, which it precipitates with water. But for the purest kinds of blue there are several processes employed; these are based upon the difficult solubility of some of its compounds in alcohol. In preparing these very pure qualities of blue, instead of starting with the crude product, one of the purified blues is taken. (To be continued). New Use for Oxygen.-We are informed by M. Widemann, who is connected with the works of the New York Oxygen Gas Company, that the use of oxygen in renewing and increasing the flow of oil in petroleum wells has been so successful that a regular trade has sprung up in oxygen gas for this purpose. The gas is injected into the wells through tubes, and, mingling with the hydrocarbon vapours, forms an explosive mixture, which, when ignited, completely opens seams which have become clogged, and thus renews the flow.-Scientific American. A NEW MECHANICAL FINGER FOR THE MICROSCOPE.* By J. ZENTMAYER. Ar the present time, when we are informed almost daily of some new scheme of gigantic magnitude, and while nothing short of connecting two worlds or two oceans, by cable, canal, or railroad, will create even a short-lived excitement, it may hardly seem profitable to call attention to a Lilliput engineering instrument, such as the Mechanical finger. But, on the other hand, while some far-sighted ones already fear this cutting through Isthmuses, tunnelling mountains, and mining whole kingdoms, might, before long, dangerously displace the centre of gravity of our earth, I can, at least, promise faithfully, that even if the instrument which I am about to describe is worked to its utmost capacity it will not appreciably disturb the equilibrium of our planetary system. In the study of diatoms it has been long desired to find a substitute for the clumsy fingers of the human hand, to do the delicate work of picking up rare and valuable diatoms detected by the microscope and to transfer them to a glass slide for preservation. Professor H. L. Smith, well-known by microscopists as the inventor of several valuable accessories to the microscope, first presented us with a very ingenious little instrument of this kind. Messsrs. John H. B. Latrobe and George Dobbin, of Baltimore, two expert microscopists, had in use for some time one of these instruments, but found it difficult to work it; and as the instrument was exceedingly well made, this proved that its construction was too complicated to give the firmness required in picking up a shell, less than one-thousandth part of an inch in length, and of which a single ounce of ocean sand contains, sometimes, many millions. Mr. Latrobe invited me to design and construct for him an instrument for this purpose. The instrument requires many adjustable movements, and each of these increases its liability to shake and spring. So I made it my object to utilise such movements, of a first class microscope stand as are not essential for other specific operations, as parts of the new finger. I found in the movements of a mechanical or sliding stage the main movements required in the finger, and so attached the apparatus to the mechanical stage. This gave me two of the most important movements, with a firmness and with dimensions of parts for which, otherwise, there would be no room. This step, however, made it necessary to provide for another stage; but as there is never a higher power than a employed with such an apparatus, a plain stage with some simple arrrangement to hold the slides would be found quite sufficient. Such a one was therefore arranged. The cut represents the finger attached to one of my large microscopes. A is the top plate of the mechanical stage; the circular plate is omitted. The cap, B, is fitted to the lower body below the stage, into which cap the new substage, c, is fastened by a narrow tube, wide enough to admit illumination from the mirror. As the lower body is movable up and down by a rack, another movement is gained which is necessary to accomplish our result. The difference of the size of the aperture of the stage and the diameter of the tube, which connects the sub-stage with the cap, A, is equal to the movement of the mechanical stage, and this is found more than sufficient. D is the clamp by which the finger is attached to the stage by means of the screw, E. A steel cylinder, G, is nicely fitted into the top and bottom of the tube, F, leaving room inside for a light spring to press the steel cylinder upwards. To prevent turning, the spring, J, is provided at H with a steel pin, accurately fitted into the fork at the top of the tube, F. By turning the Communicated by Professor Morton. From advance-sheets of the Journal of the Franklin Institute. nut, K, the spring, J, is elevated and depressed, giving nice adjustment to the needle, N, in case the finger is to be attached to a microscope, not having rackmovement to the cap, B, to bring the end of the hair and the object in close approximation. The end of the spring, J, forms a little ring, with a screw cut inside, into which a cork, M, is screwed to receive a needle, N, to which a hair is fastened by wrapping gumpaper around. Turning the cork facilitates the adjustment of the air to the proper inclination. A slight pressure on the button, L, brings down the hair, and the spring, inside of F, instantly lifts it again when the pressure is removed. The tube, F, turns in the clamp, D, in order to adjust the hair and cork more conveniently, and when brought back again it is tightened by a set screw. Complicated as it may appear, only one movement is added to the microscope stand by this instrument, the one, namely, which gives the vertical motion. When the apparatus is to be used, the material you want to select from is placed on the sub-stage, c, and focussed, then the point of the hair is approximately brought over the selected object by means of the stage movements and turning of D; this brings the hair nearly in focus too, because it is almost in the same plane with the object. We next adjust the hair recisely over the selected shell, press down the button, L, and the shell will adhere to the hair. Now we remove the slide with the material and substitute a glass slide, moistened by breathing on it, and having brought it in proper position, briskly dip down the button, L, again and the shell will be deposited on the glass slide. As the mechanical stage has a graduated indicator, the finger may be moved along regularly, and shells may be placed at equal distances in lines. After the coverglass is carefully placed over it, then Canada balsam may be run in by capillary attraction without disturbing the position of the shells. Philadelphia, April, 1870. NOTICES OF BOOKS. Report on the Quality of the Milk Supply of the Metropolitan District (New York). By C. F. CHANDLER, Ph.D., &c. New York: D. Appleton and Co. 1870. THE paper before us, an extract from the Fourth Annual Report of the Metropolitan (New York) Board of Health, opens with a statement which proves that (in matters of what is very tersely, yet aptly, called administration de la sureté et salubrité publique) the City of New York is not only not behind, but greatly in advance of a great number of European cities and towns, where investigations as regards milk supply are, as yet, in nubibus. Dr. Chandler's Report opens with the quotation of two analyses of pure milk-viz., one by Dr. Letheby and one by Hardlen. The general and well-known properties of milk are next |