CHEMICAL NEWS, Į Feb. 15, 1862. Royal Institution of Great Britain. Professor TYNDALL: The green is most reflected; and if I could catch the proper angle, I could actually quench the other altogether. There is the green; it is perfectly different. That is the under portion of the ray. Now I reflect the side of the ray; which is now most vivid? A VOICE: The red. Professor TYNDALL: So that you see the polarization of the ray still continues here; we have one ray upflected downwards, and the other ray reflected sideways. Thus you see, when once we get hold of a truth of Nature, a million courses of reasoning, a million lines of logic, will converge upon that truth, and no two will ever contradict each other. You may rely upon this, that when we have once seized hold of a truth, every additional experiment will only render that more and more firm. Well now, I have shown you two colours apart. I want now to show you these two colours actually blending together, overlapping each other, so as to satisfy you that white is really the result. I want to show you the intermediate colour. For that purpose I must use an instrument which acts like two Tourmaline crystals. By bringing them parallel, I can cause the beam to go through, and by causing them to cross I can cut off the beam. It is a polarizing apparatus, as it is called. I have a yellow and a blue disc overlapping each other, but in the centre part there is no trace of green,-it is white. Here again, I have red and green producing white where they overlap. Here again is the blue and yellow with the white. It is not, perhaps, absolutely wrong to say that blue and yellow produce green, but still if we take pure blue and yellow light, and mix them together as we have here, we produce white. As I turn the ins rument you have the different complementary colours overlapping each other and producing white. I have here another apparatus, a still harder one, dreadfully difficult to manage, but I must try it. We are not to be daunted by difficulties, so I must try whether I cannot get a beam through this or not, and if I can, I must show you some effects produced upon crystals. I think it might be worth while just to show you the two coal points actually coloured in complementary colours upon the screen. We will see whether we can colour our coal points, as it is a very pretty experiment; we will see whether we cannot build up the coal points of these complementary colours. There, we have our pair of complementary colours, and if I turn this round, you get other colours. There, you have the left hand red, and the other green, and so on as I move the instrument. Well now, let us try to get a beam through this complicated instrument. I have here some bits of gypsum, which is found in the quarries at Montmartre, near Paris; it is as transparent as glass, and yet if I send a beam through it in the apparatus-I have simply split a thin bit off with my penknife-and interpose one of these crystals, you will find that I have very beautiful colours produced. I first of all cross the two Tourmalines, and the light is completely quenched. I then take some sulphate of lime and put it in between those two, and you will find that 93 it has the power of restoring the light in a measure, and showing you these splendid colours. Thus, you see, we get these beautiful colours where there is, properly speaking, no colour at all. You have seen these varying colours, in one place it was green, in another place it was red, it is entirely dependent upon the thickness of the piece of crystal. One thickness gives me red, another thickness gives me blue. Now, here I have a piece of crystal cut from this selenite, and polished so as to form a little wedge, the edge is extremely thin, and it gradually thickens to the back. What is the consequence? As each particular thickness gives me a particular colour, you will find the colours arranged in parallel bars from the thin edge upwards. Let me see whether it is not the case. Here you see the colours showing the peculiar thickness which produces them. Here I have another piece of selenite in the shape of a lens, hollowed out in the centre so as to make the centre thinnest, and the thing gradually thickens. What is the consequence? You ought to have a series of rings because it thickens on all sides from the centre outwards. As I turn it the middle of the circle is light, and it gets darker towards the edges. This is produced by a perfectly transparent body. These are all pieces of crystals, the particles of these crystals are, as I have ɛaid, built together in the most wonderful manner by Nature herself. I have here a piece of glass, you see that when I introduce it in front of the lamp it is not at all crystalline, there is no power to act upon the light that passes through it, but if I put this piece of glass into a press and squeeze it up in the centre, in fact, bend it, it will have crystalline qualities. I will first then introduce this between the two parts of the instrument, and you will find it has no power at all, either to darken or to lighten the screen. It has no power similar to that possessed by the gypsum, no power whatever of the kind; but when I now squeeze it you will find, from the strain upon the particles, it becomes like a crystalline body. Now I want to show you that by means of this polarized light I could actually tell you the part of that glass that has been subjected to pressure and the part that has been pulled. There is part of it in a state of pressure, and part in a state of strain, and by means of this polarized light I could tell you which part is in a state of pressure, and which is in a state of strain. In fact, we have this much power over these things-that if we take a weight and compress with it, a small cube of glass, by properly examining the cube you could tell by the colour with mathematical certainty the exact amount to the pound weight, of the pressure that was exerted upon the cube of glass. Now the time is going, I am sorry to say, or I might also cause these changes by heat. For instance, here are two pieces of glass crossing each other; they have been thrust into the fire and allowed to cool, and they have been cooled in a manner so as to throw them into a state of strain similar to that in which I have drawn these pieces of glass by means of the press, and produce the same beautiful effects. Now I will take a piece of glass and heat it before you. I believe this piece of glass has no power at all for polarizing the light. But the moment I heat it its particles are drawn into a state of strain, and the glass has the power of a crystalline body. If I take a sheet of glass and heat the corner of it, you will find I have the same power. At the present time that sheet of glass has no power at all to restore the light; but if I now heat one corner, what is the consequence? You see at once this thin sheet of glass is thrown into a peculiar state of strain, and allows the light to pass, and it acts as a crystalline body, and allows the rays to pass. Here again is a very beautiful experiment that I made for the first time myself in preparing this Lecture yesterday. I took a hot poker and placed it on a plate of glass of this kind, in the middle. The hot poker disseminated its heat, and its heat passed away round about the point of contact, and the consequence was, it made the glass to expand and forced the particles-crowded them together so as to produce a beautiful black cross upon the sheet of glass. And thus I might go on with experiments of all kinds by means of the gypsum and by means of the selenite crystal I first showed you. I might cut flowers out on films of different thicknesses, and might thus produce the most beautiful bouquets, merely by a piece of crystal, there being in this no colour at all. Here, for instance, I have something which is intended for a rose, but it is not a very good one. No, I find it is a tulip; see the varying colours! There the rays of blue predominate; here, as I go round, you see a yellowish hue predominates. Here, then, we have another: that is a red rose with green leaves. As I turn the instrument round thus, it makes a monster-the leaves red and the rose blue. I must not now detain you longer. Thus, I have gone through all these glorious facts, my boys, and we have learned, I trust, something of this thing we call Light. But I will say over and over again, that you must not be content-those who pursue the subject must not be content with admiring those beautiful experiments, you must try to get at the law and order and philosophy that underlies them; that is the grand point. There are two classes of people in this world with regard to science. One class-a highly cultured class-fine fellows, noble men, generous souls, of great knowledge-men of literature; but, unfortunately, they say they have not time at all for science-they are very ignorant of science—they know nothing at all about it. These men I respect; of them there is some hope. But there is another class of men who see in science simply what it produces in the market. These are the men that will shout and yell about the electric telegraph, and about the steam-engine-anything that brings country butter to town is good and great, any thing by which you can send messages, any thing that you can bring into the market and get money for will be appreciated by these men, and they will stand by science on that account. Boys, that is not science. I cannot point you to a single great discovery in the world, in the history of science made by these men. They are not the men who make discoveries. It is those men who pursue the thing for the love of the thing whether it be natural philosophy or any other branch of science. It is those men who create these people of the market by thousands. Why, there is Volta, of Italy, and Oersted, of Copenhagen, and Mr. Faraday, of the Royal Institution; these three men have created ten thousand of your self-styled practical men. All honour to practical men as long as they do not limit to their ends the aims of philosophy. But let us pursue science for its own sake; let us not pursue it merely because it has a certain market value. I trust that when you become men, and become philosophers, you will bear this in mind, and take care to seek to draw all these men of high culture over to our side. The really great practical men sympathise with us, but the market men are incorrigible, we cannot do much with them; but with the other men you can do much. They have high and noble sympathies, and I have no doubt that by-and-bye we shall lay hold of these men, and that they, as well as you, will see that science is a glorious thing, and a noble subject for the human intellect to be engaged upon. CHEMICAL SOCIETY. Dr. E. FRANKLAND, F.R.S., in the Chair. A Paper, by Mr. ADIE, " On Ground-Ice," was read by the Secretary. He commenced by referring to Dr. Frankland's explanation of the formation of ground-ice, His observa with which he did not altogether agree. tions had been made in a district about eleven miles north of Liverpool, the surrounding country being flat, and the ditches flowing slowly. Two nights' frost was sufficient to cause a fringe of ice to form along the edges of the ditch; this afterwards becoming detached floated down the stream until some obstacle detained it, a considerable quantity having been found to collect at a bend of the stream, the weeds at this point being covered with ground-ice. Since the temperature at the surface of a piece of water was often as much as ten degrees lower than at a short distance below the surface, it was necessary that the water should be shallow. He had seen a statement that ground-ice occurs chiefly at the beginning of a frost, and that a quick, sharp frost generally produced only surface ice. He then alluded to the observations of Dr. Parkerson, who considered that the reason why streams in a flat country are most favourable for the production of ground-ice was that they are free from an under-ground supply of water, and that it had been observed that a frozen fog was a precursor of its production; also, that when the frost was not severe, so that a slight thaw took place during the day, large quantities of ice that had formed on trees during the night, fell during the thaw that followed, and, this being repeated each night, a large quantity of ice was precipitated on to the ground or into any stream that might be near. Dr. FRANKLAND said that, on occasion of a previous paper by Mr. Adie, he had proposed a solution of the phenomenon; it had struck him that since the groundice is always found on rough surfaces, this roughness, and the agitation produced in the water flowing over the obstacles, might assist the congelation, the same effect being observed to take place with solutions of salts, as, for instance, if a rough stick be plunged into a strong solution of alum; the solidification taking place at a temperature very slightly above that at which it ordinarily occurred, it was necessary that the water should be shallow, or else the bottom of the stream would not be sufficiently cooled. He thought that Mr. Adie's observations about the formation taking place at the bend of the stream confirmed this view. Mr. Adie had said that ground-ice was retained under trees, but he thought that the reason of its being found in such situations was that water, although it allows luminous heat to pass through it, resists the passage of non-luminous heat; and that, in consequence, the bottom of the water might be colder in a shaded part. Mr. PRESTWICH said, that it had been observed by M. Le Clair, that the formation of ground-ice took place at places where shadows fell on the water, and where the bed was rough, and that crystals were first formed at the side of the stones not exposed to the stream, the ice gradually extending until the stones were covered; this ice thus formed afterwards rose and floated away, carrying stones with it. He thought this fact was rather interesting to the geologist, as affording an explanation of some geological changes. Dr. SMITH remarked, that in a river which flowed along smoothly until it came to a bridge, at which point there were ripples, he had found ground-ice covering the stones at this part. Mr. CRACE CALVERT said, he had observed that ice, which had been rubbed by sliding, melted quicker than that at other parts of a frozen surface, and that, in order to ascertain whether the friction made any difference, he had taken two pieces of ice and weighed them, and then after exposing one piece to severe friction, while the other was left to itself, again taken the weight, and he had invariably found that a larger portion of the piece that had been exposed to friction was melted than of the other piece. The next Paper was by Dr. H. BENCE JONES, "On Crystalline Xanthin." A case had come under his notice of a school-boy, who suffered from incessant sickness and pain in the stomach, the urine being bloody at first, and afterwards a complete stoppage taking place; at length a violent perspiration relieved him, but a cold brought on a fresh attack; albumen was found in the water passed during the complaint, and also a crystalline deposit resembling uric acid, but redissolving by heat. The hydrochloric solution of this crystalline matter gave on evaporation six-sided crystalline plates, the aqueous solution had a feebly acid reaction; in fact, all the properties of this substance corresponded with those of the substance called xanthin, or sometimes xanthic acid; deposits of urates, however, were afterwards found, the urine having a high specific gravity. Dr. FRANKLAND remarked, that an examination of the nature of the deposits occurring in urine during different diseases was very interesting to the physiologist. Mr. A. H. CHURCH then made a verbal communication "On Silica." He first drew attention to some fossils found in some triassic red conglomerates, which contained more than ninety per cent. of silica. These fossils were originally corals, but had been altered by infiltration of water holding silica in solution. On acting on a specimen with hydrochloric acid, the remaining carbonate of lime was removed and the silicious crust left behind. He had endeavoured to produce this substitution artificially, by filtering a solution of silica, containing also carbonic acid, through a piece of coral, and the process succeeded completely. A weak solution, containing about one-half per cent. of silica answered best. All the silica was removed during the filtration, and a large quantity of carbonate of lime entered into solution. The operation also succeeded with shells, although not to the same extent. He had observed during the evaporation of a solution of silica that a number of concentric rings were found after a time in the solution, presenting a curious appearance. These rings were produced by crusts which formed all round the edge of the solution and afterwards fell into the liquid. He had found that the maximum strength of a solution which did not deposit a portion on keeping was that containing six-tenths of a per cent. of silica; a stronger solution always gelatinised after a time. A solution of chloride of barium or of calcium produced no change when added to this weak solution; but if to the stronger solutions a small piece of carbonate of lime, or of baryta, or of strontia were added, the whole immediately gelatinised, even one milligramme being sufficient to produce the effect. He had some fossils with him in which a concentric arrangement of the silica was visible; it had also been observed in shells and in carbonate of lime deposited from a solution containing gum or sugar. A MEMBER said that when a solution of silica was placed on limestones it formed a definite compound with the lime, and that skin immersed in such a solution became tanned; also, that when the solution was boiled in flasks it did not change, but in an open vessel it gelatinised in a short time. The next paper was by Mr. BLOXAM, "On Arsenic in Sulphuric Acid." He had some time ago brought forward an electrolytic test for arsenic, and had found that no samples of hydrochloric or sulphuric acid were free from this impurity. The quantity was sometimes very small, but still it would be satisfactory in medico-legal inquiries to possess an acid containing no traces of the metal. Various methods for the purification of sulphuric acid had been tried.-for instance, distillation with chloride of sodium, both concentrated and dilute acid being employed; also, passing hydrochloric acid gas through a boiling solution of sulphuric acid, electrolysing, fractional distillation, distillation with oxydising agents. None of these processes, however, were successful. He next tried oxydising sulphurous acid by passing it over pumice-stone which had been coated with platinum black, but the pumice-stone itself yielded up arsenic. Nitric oxide was next employed as an oxydising agent, the sulphurous acid 95 being prepared from sulphuric acid and copper. Mercury was employed in some of the experiments for the preparation of the sulphurous acid, on account of the arsenic present in copper. As a last resource, crystallised sulphite of soda was employed as a source of sulphurous acid; the nitric oxide being prepared from sulphate of iron, nitric acid, and sulphuric acid. This last process was the only one that furnished an acid free from arsenic. To discover the source of the arsenic, he obtained a specimen of sulphur from a manufacturer of acid which was guaranteed as free from arsenic. This specimen when burnt into sulphurous acid was found to contain arsenic, and even the residue left after combustion contained traces of the metal. In preparing an acid free from arsenic he had found that it was necessary to conduct the operation at as low a temperature as possible. Dr. FRANKLAND said it would be very satisfactory if sulphuric acid free from arsenic could be prepared in any quantity. A MEMBER mentioned a modification of Pelouze's method of determining sulphur in iron pyrites, recently published in the CHEMICAL NEWS, which was as follows: Melt the ore with chlorate of potash, chloride of sodium, and carbonate of soda, and determine the excess of carbonate remaining after the experiment. This precaution was, however, necessary; if arsenic were present in the pyrites the arsenic acid formed would neutralise the carbonate, and consequently the calculated per-centage of sulphur would be too high. To rectify this, however, all that was necessary was to use a standard solution of hydrochloric acid for the determination of the alkalinity, and afterwards to precipitate the sulphuric acid by means of chloride of barium, and in this way to determine the sulphur; the amount of arsenic could then be easily calculated. Mr. DUGALD CAMPBELL inquired what was the smallest amount of arsenic that could be detected by Mr. Bloxam's method, for by his own method, which would detect a very small quantity, he had found samples of sulphuric acid which were free from arsenic, but that it was always present in samples of hydrochloric acid, and that it was more important to obtain this latter acid pure. He also stated that he had found arsenic in common salt. Mr. BLOXAM said that he had distilled common salt with sulphuric acid, and had found arsenic in the distillate, but that he obtained none from chloride of ammonium and sulphuric acid. Mr. F. A. ABEL then read a paper "On a Deposit occurring in Teak Wood." He had observed in many specimens of this wood which had come under his notice, deposits of a white substance intersecting the wood, in the form of layers converging towards the centre or heart of the tree. These layers which were sometimes soft and pulverulent, and at other times so hard as to blunt the cutting edges of the saws employed, were often several feet in length, six or eight inches in breadth, and from one to three-eighths of an inch in thickness; they had evidently been deposited in flaws or cracks which had formed in the living tree. Cavities occasioned by knots in the wood were frequently filled with the same white deposits, as were also perforations of considerable size and length constantly found in teak wood, which were produced by a large caterpillar. This white deposit exhibited occasionally a distinct striated crystalline structure, at other times it consisted of conglomerates of small acicular crystals; it was readily soluble in dilute acids with separation of a small quantity of organic colouring matter, a very minute quantity of carbonic acid being evolved. The analysis of an average specimen of this deposit, dried in vacuo, furnished the following per-centage results : 19'54 From the relations which the amounts of magnesia and ammonia bear to each other, it was concluded that they were present in the form of the ordinary ammonio-magnesian phosphate, the amount of which would be 11:43 per cent. Deducting the phosphoric acid contained in this salt, the remaining phosphoric acid, the lime, and the water were nearly in the proportion in which they exist in the phosphate of the formula 2 CaO, HO, PO5+2 Aq. He thought it possible, however, that the deposit might consist of variable mixtures of amorphous and crystalline diphosphate of lime. Dr. FRANKLAND asked whether the deposit appeared to be diffused through the sound parts of the wood, and if in this case it would at all account for its durable properties. Mr. ABEL replied that although it was diffused through the wood to some extent, he did not think it was the cause of is durability, although other hard woods were found to contain a similar deposit. The next paper was by Dr. J. SMITH, of Sydney, "On the Composition of the Water of Certain Boiling Springs in New Zealand." Some of these boiling springs were intermittent, many of them having formed terraces of silicious matter. He had made an analysis of the water of one of those in which the supply was copious. The water had a pale blue colour, and descended in cascades; it was in a state of violent ebullition. The portion collected became milky after a time, and acquired a faint smell of sulphuretted hydrogen; its specific gravity was 1'00205, and it had a sediment of vegetable matter in it. The following substances were found in the water, the amounts being calcu lated in grains per gallon : The amount of carbonic acid present was small; no boracic acid was found. Other samples from different springs differed a little in composition. The water formed white incrustations on reeds or other plants, the deposit being spongy in some cases, while in others it was dense; it was sometimes tinged with pink, presenting a very beautiful appearance. The water was met with of every temperature up to a few degrees above the boiling point of pure water. When solid bodies were immersed in the water they became petrified, and some plants growing near seemed to have been petrified by the splashes while still living, even the flowers being preserved in some cases. The waters differed slightly in the same locality; for while some were alkaline, others were slightly acid. Dr. FRANKLAND remarked that it was interesting to find the same changes going on at the Antipodes as on our own side of the globe, these ice springs being analogous to those found in Iceland. NOTICES OF PATENTS. 983. Manufacturing Oxygen Gas, and obtaining certain other Products. J. WEBSTER, Birmingham. Dated April 20, 1861. (Not proceeded with.) THIS invention consists in heating mixtures of nitrate of soda or other nitrate with crude peroxide of iron, for the purpose of obtaining oxygen gas, compounds of nitrogen, and the base of the saline material employed. The method of preparing oxygen here suggested would not be so advantageous as that proposed by M. Deville for obtaining this gas by the decomposition of sulphuric acid by heat. 988. Bleaching and Refining Oils. A. V. NEWTON, Chancery Lane, London. A Communication. Dated April 20, 1861. (Not proceeded with.) BROWN binoxide of lead, either alone or in combination with other materials, is proposed to be employed for the purpose of bleaching and refining oils and fatty substances. The efficacy of binoxide of lead as a decolorising agent is indisputable, especially when employed together with an acid; but there would always be a tendency for the fatty matter to become contaminated with lead by union with the protoxide. 1006. Sulphuric Acid. P. WARD, Bristol. Dated April 23, 1861. For the purpose of accelerating the formation of sulphuric acid from the mixed gases in the leaden chambers, the inventor employs fragments of sheet glass, or other materials upon which the acid has no solvent action, exposing a large extent of surface, which is kept constantly moist by retaining a film of the acid. Spongy platinum, and even pumice-stone coated with the reduced metal, are known to facilitate the combination of various gases, and there is no doubt that inasmuch as fragments of glass are found to lend assistance in the union of oxygen and nitrogen, they will exert the same power in favour of the more rapid production, in their presence, of sulphuric acid from the mixed sulphurous and nitrous gases. 1008. Purification of Coal Gas. T. RICHARDSON, Newcastle-on-Tyne. Dated April 23, 1861. (Not proceeded with.) THIS proposition consists in reducing the crude oxides of iron, left as secondary products when pyrites ores are used in the manufacture of sulphuric acid, by the action of carbonic oxide, hydrogen, or other deoxidising gas employed at a high temperature; and in utilising the resulting material in the purification of coal gas. The efficacy of the proposed material would be considerably augmented by allowing the reduced iron to become rusted by the action of a moist atmosphere, an improvement which could not, however, be carried out without infringing the patent rights of Mr. Hills, whose claim to the employment for these purposes of the hydrated oxides of iron has recently been proved in a Court of Law. 1019. Artificial Manures. C. STEVENS, Charing Cross, London. A Communication. Dated April 24, 1861. WITH the object of preparing a manure which shall contain a variety of fertilising ingredients, a mixture is compounded of the materials, and in the proportions, undermentioned : Woollen rags Soda crystals Lime (slaked) Sulphate of iron. Sulphate of magnesia. Sulphate of ammonia. Superphosphate of lime Water 100 parts. 1084. Treatment of certain Ores Containing Metals. R. LAING, Ince, near Wigan, and J. SWINDELLS, Wigan. Dated May 1, 1861. FOR the purpose of extracting copper and other metals from their ores, the patentees prefer to employ acids in the CHEMICAL NEWS, Feb. 15, 1862. Correspondence-Chemical Notices. gaseous state, and to economise for this application the spent gases evolved from the sulphuric acid chambers, and sundry other products, particularly the waste hydrochloric acid generated in the manufacture of "salt-cake" in alkali works. Soluble compounds of copper or other metal are produced which may be extracted from the residual ore by washing. 1072. Certain New Chemical Combinations, and for the Application thereof to Fixing Aniline and Pigment Colours in Printing and Dyeing, and other Industrial Purposes. J. MEYER, Berlin. A Communication. Dated April 30, 1861. THIS invention consists in the combination of certain organic substances, such as fibrine, albumen, gelatine, animal tissues, and other similar materials with the oxides or salts of tungsten and molybdenum. It is very probable that the tungstate of soda, in conjunction with any one of the animal matters enumerated, will operate as a mordant and be susceptible of the same applications as the stannate of soda. 1087. Colouring Matters Derived from Naphthaline, and Application of the same to the Dyeing and Printing of Fabrics. F. Z. ROUSSIN, Paris. Dated May 1, 1861. (Not proceeded with.) THE inventor prepares in the first place nitro-naphthalase by the action of nitric acid on crude naphthaline. This product is then dissolved in hydrochloric acid and submitted to the reducing influence of nascent hydrogen, &c., by contact with tin (or pewter), in which reaction the base naphthalidine is formed. The hydrochlorate of this last named substance is then finally brought into contact with nitrite of potash or hyponitric acid, either of which leads to the production of a red colouring matter, tolerably permanent, and applicable in the dyeing processes. In the earlier stages of this method of preparation, compounds are formed which were described many years ago by Zinin. The naphthaline products have lately been made the subject of renewed investigation, and promise to furnish a valuable series of colouring matters. 1092. Fixing Colours in Connection with the Printing and Dyeing of Woollen Fabrics and Yarns. R. T. PATTISON, Daldorch House, Ayr. Dated May 1, 1861. (Not proceeded with.) THIS invention refers to the employment of the alkaline earths or soluble salts, without being combined with tannin or other organic materials, for fixing certain colours derived from the products of coal tar, upon yarns and woven fabrics in the processes of printing and dyeing. 1099. Stearine. E. DE BASSANO and A. BRUDENN, Brussels. Dated May 2, 1861. (Not proceeded with.) In the process of distilling the crude fatty acids as a means of purification, the inventors recommend the addition of powdered wood or animal charcoal, lamp black, or coal, for the purpose of retaining certain empyreumatic substances which are apt to distill over and contaminate the product. 1109. Manufacture of Paper and Cardboard from a Fibrous Vegetable Matter, M. A. F. MENNONS, Paris. A Communication. Dated May 3, 1861. THIS improvement consists in manufacturing paper from the concretions of vegetable matter known as "pommes de mer," or marine apples, and which, formed by the rolling action of the sea on a certain variety of alga (Zostera marina), are found in abundance on the shores of the Mediterranean. 1113. Electric Telegraphs. O. ROWLAND, Wellington Road, Kentish Town, Dated May 3, 1861. (Not proceeded with.) THE suspended conducting wires of the electric telegraphs 97 whether of iron or steel, are, according to this invention, protected from the atmosphere by being coated with antimonial lead, or with alloys of tin and lead, or the latter metal with addition of antimony. The expense attending the application of these metallic coatings would be greater than is the case with zinc, but the ordinary galvanizing seems but ill-fitted to protect the iron wire from the effects of atmospheric exposure. CORRESPONDENCE. Mounting Microscopic Objects. To the Editor of the CHEMICAL NEWS. SIR,-Perhaps some of your subscribers may know, and, if so, will be kind enough to inform me, how I may prepare a solution of silicate of potash or soda fit for mounting microscopic objects. I have found it, in many respects, suitable for the purpose, as the exuding portion becomes semi-solid in a few minutes, when it may be removed with a knife; and the varnish adheres without any of the difficulty and loss of time so often experienced with preservative solutions, and more especially glycerine; nor is there any danger of its running in. But I was disappointed to find that, even when the edges of the thin glass cover were varnished, it always became milky or crystallised, sometimes in a few hours, sometimes not for a week. It is recommended in the "Micrographical Dictionary" on account of its low, refractive power; but the author also states that his specimens became opaque, which he attributes to excess of alkali. valuable space, did I not believe that a receipt for a I should not venture to ask for so much of your silicate which will remain transparent will be a great boon to microscopists. I am, &c. Fusibility of Oxide of Cadmium. A. H. To the Editor of the CHEMICAL NEWS. SIR,-All chemical books agree that oxide of cadmium is infusible. We have found it to be otherwise. Some nitrate of cadmium being precipitated with carbonate of soda, the resulting carbonate of cadmium was thoroughly washed with hot water, and dried. The white powder, after being well ground, was put into a clay crucible and strongly heated in a fierce coke furnace. In a few minutes the usual conversion into brown oxide took place. In about half-an-hour, however, a red-hot mass was formed. This, when cold, was of a blackish colour, speckled on the surface with brown; and could only be got out of the crucible by breaking the latter, portions of which adhered with great tenacity. Fused oxide of cadmium is very heavy, and yields, on grinding, a brownish-grey powder, not so readily soluble in acids in the cold as the ordinary brown oxide. We are, &c. February 11. THOMAS SALTER, F.C.S. HENRY MATTHEWS, F.C.S. Chemical Notices from Foreign Sources. I. ORGANIC CHEMISTRY. Kreatinine in Urine.-Dr. C. Neubauer has demonstrated (Ann. der Chem. und Pharm., Bd. cxix., s. 27,) that Kreatinine is a normal ingredient of urine, always present in about the same proportion as uric acid. He separated it by forming a double compound with chloride of zinc. |