The photographic news

• Bandzählung: 7.1863
• Erscheinungsdatum: 1863
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-186300004
• PURL: http://digital.slub-dresden.de/id1780948042-18630000
• OAI: oai:de:slub-dresden:db:id-1780948042-18630000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

592 THE PHOTOGRAPHIC NEWS. [December 11,1863. by the workman, from the rock, and scattered at random for others to utilise. Foremost amongst the vigorous miners in organic che mistry stands Dr. Frankland. Scarcely a month passes without chemists being gratified by some new result, which this talented professor has elaborated with no less skill than penetration. His discoveries, especially in relation to organo metallic bodies, are always of interest; and his latest research promises to be of some practical importance, besides being of scientific value. By allowing iodide of methyl to act upon sodium amalgam, in the presence of a little acetic ether, a compound is obtained called mercuric methyl. This, after purification, is obtained in the form of a colourless, highly refracting liquid, of the specific gravity 3’069, being in fact the heaviest known liquid, with the exception of mercury itself. So dense is it that a piece of heavy lead glass will float upon it. The author states that in the event of this organo-mercuric compound being required in quantity, no difficulty would be experienced, as iron vessels could be used, and the process could be con ducted continuously; thus syphon tubes could be made to draw off the residual mercury, and the products themselves, whilst fresh materials could be supplied by injection. Upon seeing the specimen of mercuric methyl handed round at the last meeting of the Chemical Society, the idea occurred to an ingenious correspondent of the Chemical News to apply this liquid to the manufacture of prisms. At present, the only liquid suitable for this purpose is bisulphide of carbon, which is not above half the density, besides being objection able from its offensive odour, its great volatility, and the ease with which it ignites. The mercuric methyl appears to be superior to bisulphide of carbon in all these respects; and as its preparation in quantity would be attended with no particular difficulties or expense, we hope that some enter prising instrument maker will not be long in adopting this very valuable suggestion. Besides its use for prisms, this liquid might be advantageously employed in the manufac ture of lenses. Formerly, compound lenses, in which one of the constituents was a fluid held between outer meniscus lenses, were somewhat in vogue, but were abandoned owing to the advantages of their construction not being sufficiently great to counterbalance the difficulties. The well-known French chemist, Chevreul, who has devoted so much attention to the subject of colour, has lately published a memoir on painted windows, in which there are many points which deserve the attention of artists and others who are interested in the manufacture of coloured glass. It has often been noticed that old stained glass windows have a much richer effect than modern ones, and M. Chevreul, speaking of this superiority, attributes it to what we moderns regard as defects. In the first place, much of the ancient glass is of unequal thickness, or, in other words, the two surfaces are not parallel, and so present convex and con cave parts, which refract the light differently, and produce an agreeable effect. In the next place, the old coloured glass is not a colourless glass, to which has been added the particular colouring material, such as protoxide of cobalt, &c. Old glass 1 contains a good deal of oxide of iron, which colours it green, and to this must be attributed the peculiar effects of antique glass coloured by cobalt and manganese. M. Chevreul appears to think that modern stained glass is too transparent to produce tho best effects. M. Regnault, another admirer of the “ dim religious light,” has recom mended that all this kind of stained glass should be cast, to avoid the monotonous effect of plain surfaces on the light; and also that foreign substances should be mixed with the glass to diminish its transparency. The formation of gun cotton from ordinary cotton is well known to our readers; the change consists in the substitu tion of two or more equivalents of nitrous acid, NO,, for the same number of equivalents of hydrogen. The same change may be produced in many other organic bodies; for in stance, glycerine, when treated with a mixture of nitric and sulphuric acids, becomes converted into a nitro-glycerine or glonoine, an oily liquid having explosive properties when heated. Many experiments have been tried with this sub stance, respecting the remarkable action which it exerts upon the animal economy, the glonoine being administered by dropping it, or its alcoholic solution, upon the tongue. The principal effect which has been noticed is the production of violent headache, accompanied by great prostration of the system. Mr. T. M. Merrick has recently had tho courage to try some experiments upon himself, and, con sidering the violent toxical properties of this curious sub stance, and the peculiar manner in which it acts, the ex periments are doubtless more interesting to the reader than to the experimenter. The first experiment was an accidental one ; a dish containing a solution of glonoine in ether was, by some mishap, tipped over, spilling half its contents on the sand bath, and, in a moment, the room was full of the mixed vapour of glonoine and ether. A large volume of the mixed vapour was inhaled. No immediate bad result followed, but in less than fifteen minutes a headache set in, slight at first, but increasing in inten sity by degrees, until, in an hour and a half, it became almost intolerable. It was accompanied by a good deal of faintness and exhaustion, intolerance of light, and a feeling of great general distress and alarm; consciousness, however, not being lost for an instant. The unpleasant symptoms did not disappear for three or four days. After this experience of the powerful action of the liquid, Mr. Merrick was a bold man to deliberately lay himself out for a repetition of the effects ; but there is no knowing what an enthusiast will do in the cause of science. Wishing to ascertain what would be the effect of swallowing a minute quantity of glonoine, he prepared a solution containing two and a half drops to ninety-seven and a half of alcohol. One drop of this liquid, containing the fortieth of a drop of glonoine, was swallowed on a piece of loaf sugar. In two minutes the pulse had risen considerably, with a dull throbbing headache. In five minutes the pulse had risen higher, the headache changing from the back to the front of the head. In fourteen minutes the pulse had sunk again to its normal rate, although the pain in the head did not pass off for fifteen minutes more. This experiment shows that glonoine is a body which rivals in intensity the strong est organic poisons; it proves the necessity there is for extreme caution in handling, and especially inhaling or tasting substances the nature of which is not thoroughly well known. In inexperienced hands, glonoine may be a poison of the most mischievous character; although when employed by skilled physicians, it will, no doubt, prove a valuable physiological agent. Messre. Deville and Troost have lately discovered a curious property of platinum. In some experiments upon high tem peratures, they were induced to suspect that the platinum vessels employed were somewhat porous to gases. They accordingly tried a definite experiment, with the object of ascertaining this. A platinum tube was placed inside a porcelain one : through the former a current of atmospheric air was passed, whilst hydrogen circulated through the latter. The pipe and delivery tubes were so arranged that the gases could not mix, but passed through and were collected apart, being separated by a solid and continuous parti tion of well worked platinum. At the ordinary temperature the hydrogen passes along and may be collected at the other end in the pure state, whilst the air retains its normal composition. When the temperature is raised, however, to a red heat, a change occurs, the platinum at this temperature is porous to the hydrogen, which accordingly passes through the metal, and unites with the oxygen of the atmosphere, forming water, which may be collected and weighed in appropriate apparatus. It has been proved further that the porosity increases with the elevation of temperature : at the highest point tried (about 1,100° C.) the whole of the atmo spheric oxygen unites with tho hydrogen, and nothing passes out at the other extremity of the apparatus but nitrogen and aqueous vapour.