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Chemical Notices from Foreign Sources.

CHEMICAL NEWS,
April 10, 1879.

if they came back, as I thought they might possibly be | CHEMICAL NOTICES FROM FOREIGN due to other causes. However, she would not.

I analysed the paper and found o'35 grm. As203 per square foot, but that will scarcely represent the total amount because the paper was wetted in order to remove it, and the greater proportion of the bright green flowers washed off. There was very little copper present. I may

SOURCES.

NOTE.-All degrees of temperature are Centigrade, unless otherwise expressed.

mention that the lady's husband was not affected in the Comptes Rendus Hebdomadaires des Séances, l'Académie de

slightest degree.—I am, &c.,

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To the Editor of the Chemical News. SIR,-With reference to the methods for the manufacture of potassium iodide as described by E. Schering (CHEMICAL NEWS, vol. xxxix., p. 118), he very justly ascribes the chief objection to the process in which iodine is introduced into caustic potassa and fused with carbon, to be the difficulty of obtaining caustic potassa of sufficient purity, the presence of sulphate and soda salts being most objectionable. A caustic potash practically free from these and other impurities has hitherto been unobtainable at a commercial price, and the introduction of such an article suitable for the manufacture of potassium iodide and other industries has long been a desideratum in the chemical world. This difficulty has but lately been removed by the manufacture on the large scale of caustic potash at St. Helens, by the Greenbank Alkali Works Company, of a purity which leaves nothing to be desired, a sample which recently came under my notice possessing total impurities under one per cent, of which only o2 was in the form of sodium hydrate. The removal of the difficulty of obtaining a caustic potash of the necessary purity being removed, the process as described above for the manufacture of potassium iodide appears to me to be the simplest and best, and having at one time been engaged in the manufacture of the article, I can therefore speak with some experience.—I am, &c.,

St. Helens, April 3, 1879.

A. R. GARRICK, Ph.D., F.I.C.

OBITUARY.

J. M. MERRICK.

WE regret to announce the death of Mr. J. M. Merrick, of Boston, U.S., who was an occasional contributor to our columns. Mr. Merrick died on the 25th day of February last, at the early age of forty-one years. In his professional life he had gained the respect of all who knew him by his uprightness of character and the ready courtesy with which he imparted his knowledge to other members of the chemical profession.

An Electric Blowpipe.-M. Jamin.-The author remarks that the electric arc which plays between two carbon conductors is a true current. If submitted to the influence of a neighbouring current, of a solenoid, or of a magnet, it experiences an action regulated by the laws of Ampère, identical with that experienced by any metallic conductor put in its place, but as its mass is exceedingly trifling its speed is considerable. The author takes advantage of this fact to submit small quantities of matter to an intense heat. By causing the arc to be driven upon lime, magnesia, or zirconia the light is directed downwards, and its intensity is increased least three-fold.-Comptes Rendus.

New

des Sciences. No. 11, March 17, 1879. Experiments on Telephones without Diaphragm.-M. Ader.-The author's experiments demonstrate the truth of the opinion of M. du Moncel concerning the origin of the sounds reproduced in the telephone.

New Combinations of Hydrochloric Acid with Ammonia.-L. Troost.-The author remarks that hydrochloric acid and ammonia have hitherto been obtained only in the proportions which form sal-ammoniac, analogous to common salt. No hydrochlorate of this chloride has yet been discovered, nor an ammonic hydrochlorate with excess of base. He has discovered a great number of curious compounds formed by dry ammonia with hydrochloric acid, hydrosulphuric acid, and other acids, both mineral and organic. He takes ammoniacal gas absolutely dry and free from every trace of compound ammonias, saturates it with pure dry hydrochloric acid, and submits the sal-ammoniac thus obtained and distilled in a close vessel to the action of a large excess of gaseous ammonia, refrigerating to different degrees. He thus obtains two well-defined compounds, characterised by their point of fusion, their crystalline structure, and their tension of dissociation. The former of these, tetra-ammonic hydrochlorate, HC1,4NH3, melts at +7o, and its crystals depolarise light powerfully. The other compound, hepta-ammonic hydrochlorate, HCl,7NH3, melts

at -18°.

Combinations of Hydrogen Phosphide with Cuprous Chloride and its Determination in Gaseous Mixtures.-J. Riban.-The compound Cu2Cl2,2PH3, chloride of cuproso-diphosphonium, is obtained by slowly passing hydrogen phosphide into a solution of cuprous chloride, refrigerated by means of ice. Hydrogen phosphide present in gaseous mixtures may be determined by agitation along with a solution of cuprous chloride in hydrochloric acid.

The Crystalline Forms of the Compounds of the Stanmethyls and of their Homologues.-M. Hiortolahl. Not susceptible of useful abstraction.

New Method of Treating Iron and Copper Pyrites in the Dry Way.-L. Simonin.-An account of J. Hollway's experiments.

The State in which the Precious Metals are found in some of their Combinations, in Ores, Rocks, and Artificial Products.-E. Cumenge and Edmond Fuchs.

The authors find that in certain pyrites gold is found not native but in combination with antimony, and is incapable of being taken up by mercury.

Constitution of Coal.-E. Guignet.-The author on treating dry powdered coal with phenol has extracted as much as 4 per cent of a brown matter. If coal in very oxalic acid and trinitro-resorcin are distinctly recog fine powder is treated in a cohobator with nitric acid, in the coa nisable among the products. Resorcin was not detected

Alcoholic Fermentation.-P. Schützenberger and A. Destrem.-If yeast is placed in such conditions as to prevent its development and multiplication it nevertheless preserves its power of decomposing sugar, and if it acts upon sugar it de-assimilates more nitrogen than if preserved in presence of water without sugar and oxygen.

Determination of Glucose in Blood.-P. Cazeneuve. at-The author criticises the method of determination followed by C. Bernard as the progress of the reduction of

NEWS

the cupro-potassic liquid is often uncertain when the reaction approaches its limit. It is also reduced by other principles present in the blood. The author thinks that glycemia should be studied anew when a more accurate analytical procedure has been devised.

Derivatives of Normal Methyl-oxyl-butyric Acid. -E. Duvillier.-An account of the methyl-oxyl-butyrates of ethyl and methyl and of methyl-oxy-butyramid.

Nature of the Albumen of Hydrocele.-M. Bechamp. -Three distinct albumens are present different from

blood albumen.

Modifications of the Physical Properties of Starch. —F. Musculus.-Amylaceous matter may exist either in the colloid or the crystalloid state. When crystalline it is soluble even in cold water.

action of sulphuretted hydrogen upon glyoxylic acid in presence of silver oxide.

Mineral Waters near Buda Pest.-M. Ballo.-This

memoir may possibly be of medical interest.

Studies in the Naphthalin Series.-Raphael Meldola. The object of this communication is to throw light upon the constitution of the naphthalin derivatives. The author gives an account of dibrom-acet-naphthalide.

Sulph-etheric Acids of the Phenols.-E. Baumann In describing the sulpho-cresolic acids, the author remarks that the sulpho-para-cresolate of potassium is a constant ingredient in the urine of horses and probably also of other mammals.

Bromo-acetic Ethyl-ether.-F. Kessel.-A lengthy memoir, not adapted for abstraction.

Action of Dry Ammonium Sulphate upon Dry Barium-ethyl Sulphate in Presence of Baryta.-H.

Berichte der Deutschen Chemischen Gesellschaft zu Berlin, Koehler.-The author obtains ethyl-amin, but in small

No. 15, 1879.

The Chloranilins.-F. Beilstein and A. Kurbatow.

An account of the di-, tri-, and tetra-chloranilins. The authors propose to found the nomenclature of these compounds on the relative position of the chlorine atoms.

quantity only.

Hydrochloric Acid.-H. Koehler.-The products formed
Decomposition of Ethyl-sulphates by Gaseous
are free sulphuric acid, barium sulphate, and chlor-ethyl.
Tropæolin as an Alkalimetric Indicator.-Dr. Lunge.
-The author confirms the statements of Miller concern-

carbonate, and for determining the free acid in alumina.
Not merely the carbonate but sodium sulphide (in the
crystalline state) may be accurately titrated in the cold
with sulphuric acid, using tropaolin as indicator. On
the slightest excess of acid appearing, the yellowish
colour changes at once to a magenta and then to orange,
which after a few seconds disappears entirely.
pæolin 000 undergoes the reversed play of colour, being
yellow in acid solution, but turning to a magenta-red in
alkalies.

Para-di-propyl-benzol and Certain of its Derivatives.-H. Körner.-An account of sulpho-para-di-propyling the use of tropaolin 00 for the titration of sodium benzolic acid with its lead, barium, and calcium salts; of dinitro-para-di-propyl-benzol, and of propyl-benzoic acid. Determination of Vapour-Densities.-V. Meyer.Not intelligible without the accompanying engraving. Occurrence of Furfurol in Commercial Glacial Acetic Acid.-V. Meyer.-The author has found that glacial acetic acid, represented as containing from 99 to 100 per cent of real acid and apparently of unexceptional quality, assumed a splendid red colour on contact with aniline, but lost this property on distillation with chromic acid. This colouration was due to the presence of furfurol of which o'108 grm. was found per litre of acid.

Variability of the Colouring-matter of Red Wine. -J. Erdmann.-The author traces decided differences in the behaviour of genuine wine of one and the same growth according to its age.

Spectroscopic Researches on the Constitution of Solutions.-H. Burger.-In this paper the author communicates merely his methods of observation.

Malabar Gum Kino and a New Compound, Kinoin. -C. Etti.-The author added kino to twice its weight of boiling dilute hydrochloric acid (1:5). Kino-red separates out as a soft mass, which slowly hardens on cooling, while the kinoin remains in solution, contaminated with a little kino-red. When purified it crystallises in colourless well-formed prisms, sparingly soluble in cold water, readily at a boil, and very easily in alcohol of every concentration. The solution is not precipitated by glue and is coloured red by ferric chloride. The composition of kinoin is C14H12O6.

Mono- and Diphenyl-arsenic Compounds.- W. La Coste and A. Michalis.-The readiness with which phosphenyl chloride can be obtained from phosphorus chloride and benzol induced the authors to examine if this reaction could not be generalised so as to serve for the preparation of the corresponding arsenical compounds.

Tri-phenyl-arsin and its Derivatives.-W. La Coste and A. Michalis.

Mono-tolyl-arsenic Compounds.-W. La Coste and A. Michalis.-These two papers may be regarded as continuations of the foregoing.

Schizomycetic Fermentations.-An examination of the fermentations of erythrite, glycerin, mannite, citrate of lime, malate of lime, &c., infected with cow-dung, infusion of hay, and certain varieties of purulent matter. Thioglycolic and Thiodiglycolic Ethers.-C. Böttinger. The author has obtained these products by the

Reimann's Färber Zeitung,
No. 11, 1879.

Tro.

Two new green dyes have been introduced into practical use; the Vert acide of A. Poirrier, of Paris, and the Victoria green of the Badeh Aniline Company. The price of the latter is only 16s. per kilo.

The red azo-colouring-matters are fast superseding cochineal in the flannel dye works of Saxony. They have the advantage of not being injured by washing.

No. 12, 1879.

Washing Wool with Ether and Alcohol.-The result of the experiments made at Ensival, near Verviers, is stated as follows:-70,000 kilos. wool and 16,000 kilos. yarn were extracted. The former yielded 15,800 kilos, of oil, or 22.6 per cent, and the latter 2400 kilos., or 15 per cent. The oil was sold at 39 to 40 francs per 100 kilos. The loss of ether amounted to 4'9 kilos. per 100 kilos. o wool treated.

No. 23, 1879.

It appears that milk is dyed in the cows. If fed with Anchusa tinctoria they yield a blueish milk, if with Rheum palmatum a yellowish, and if with madder or bed-straw (Galium) a reddish.

Justus Liebig's Annalen der Chemie,
Band 196, Heft 1.

Constitution of Phenanthren.-Gustav Schultz.The author infers that phenanthren-quinon and consequently phenanthren are to be regarded as diortho-compounds.

On Phenanthren-quinon.-R. Anschütz and Gustav Schultz.-An account of the preparation of this compound and its behaviour with aqueous alkalies and lime, with alcoholic potassa, and alcoholic ammonia.

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Researches on Hydrogen Peroxide.-E. Schoene.The author has investigated the behaviour of hydric peroxide with the oxygen compounds of thallium. He finds that thallium paper is turned brown by the vapour of hydric peroxide in consequence of the formation of thallic oxide. Hence the browning of thallium test-papers on exposure to atmospheric air is by no means a proof of the presence of ozone.

On Aurin.-R. S. Dale and C. Schorlemmer.-The authors describe their conversion of "red corallin" or "peonin" into rosanilin. They have further examined ammonia-aurin, tetrabrom-aurin-which latter compound is very similar to tetrabrom-rosolic acid, soluble in alkalies with a fine violet colour, whilst its acidified solutions dye silk and wool a dark violet. They have further investigated the action of acetyl chloride and anhydrous acetic acid upon aurin, the compounds of aurin with acids. The compounds of aurin with acids are red like the aurin itself, whilst those with the acid sulphites of the alkali metals and with anhydrous acetic acid are colourless like leukaurin. The homologue of aurin rosolic acid likewise forms with acids well crystallised compounds, and as a powerful base. Hence it should not be considered as an acid, and might be more appropriately named rosaurin.

On Pyruvic Acid.-Dr. C. Böttinger.-The author shows that the quantity of pyruvic acid obtained from glyceric acid is so trifling that it is inadmissible to make use of this manner of formation for the deduction of a constitutional formula for the latter acid. The demonstrated identity of the sulpho-lactic acid from pyruvic

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CHEMICAL NEWS,
April 10, 1879.

SCIENCE

BIOLOGY, ASTRONOMY, GEOLOGY, INDUSTRIAL ARTS

MANUFACTURES AND TECHNOLOGY,

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acid and from a-chlor-propionic acid is evidence for the EX

ketonic character of pyruvic acid.

Communications from the Chemical Laboratory of the University of Kasan.-These consist of papers on Allyl-dipropyl-carbinol, by P. and A. Saytzeff; and on Allyl-di-ethyl-carbinol, by A. Schirokoff and A. Saytzeff. Action of Tertiary Butyl-iodide on Isobutylen in Presence of Metallic Oxides.-J. Lermontoff.-Not susceptible of useful abstraction.

IN

PURE, APPLIED, AND PHYSICAL CHEMISTRY. By mistry in the Royal School of Mines, &c. E. FRANKLAND, Ph.D. (Marburg), D.C.L., F.R.S., Professor of Che

ALSO BY PROFESSOR FRANKLAND,

LECTURE NOTES

4s.

Tetra-methyl-ethylen and its Derivatives, and the Ch

Chemical Structure of Pinakon.-D. Pawlow.-Not suitable for abstraction.

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ERRATA.-P. 97, col. 1, line 6 from top, for 25 to 30 per cent read 025 to 0.30 per cent. Line 14 from top read o'25 to 0'26 per cent

FOR CHEMICAL STUDENTS. Post 8vo., Fifth Thousand of Vol. I. (Inorganic) Second Edition of Vol. II. (Organic), 5s.

JOHN VAN VOORST, 1, Paternoster Row.

hemist (age 21), who has studied for five years in Scotch and German Laboratories, and who has had considerable experience in analysis and research, desires Engagement as Assistant Chemist in a College or Works. Good references.Apply, J. T., 26, Royal Exchange Square, Glasgow.

The

here is an excellent opening for a Youth, with a knowledge of Chemistry, in a Laboratory, where he will have the advantage of improving himself and gaining experience in commercial analyses.-Address, Beta, CHEMICAL NEWS Office, Boy Court, Ludgate Hill, London, E.C.

The
'he Runcorn Soap and Alkali Co., Limited,
Apprentice for three or four years.-Apply by letter only to the
Runcorn, are in want of a Youth in the Laboratory as an
Runcorn Soap and Alkali Co., Limited, Runcorn.

TO MANURE MANUFACTURERS.

OR SALE.-About 150 tons Monthly of

FOR

Woollen Shoddy Manure; free from grease; containing nitrogen equal to from 5 to 10 per cent ammonia.-Apply to David Shaw, near Clayton, Manchester.

TO CHEMISTS, &c.

Shop and Excellent Dwelling-house at Chisle

hurst (Lower Camden, close to the Railway Station), TO BE LET ON LEASE, without premium. It occupies a prominent position, is certain to command a good family business, and is weil adapted for the district Post and Telegraph Office, which is much needed. A low rental would be accepted for the first three years. Apply at Mr. David J. Chattell's Estate Agency Offices, which adjoin.

TO BE LET.-An Eligible Dwelling-House, SOUTH LONDON SCHOOL OF PHARMACY. in analytical practice or for classes in practical chemistry. Possibly

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with Laboratory fitted complete, suittable either for a Chemist

a small incoming. Rent very moderate.-For price of fixtures and fittings and further particulars apply to E. and S. Smith, Auctioneers and Agents, 22, Southampton Buildings, Chancery Lane, W.C.

MR.
Tickets £2 25. each, to be had of W.

Baxter, Secretary, at the Office of the School, Kennington Cross,
S.E.

R. COX, VALUER OF CHEMICAL PLANT, offers his services on the usual terms. Twenty years' experience, Estimates for all description of plant, plans, &c.-Glenmohr House, New Charlton London, S.

NEWS

made the subject of study by the lecturer during the last THE CHEMICAL NEWS. ten years, and some of the earlier results published by him in connection with this subject also led to the pursuit of experimental inquiries of analogous character by Champion and Pellet and others.

VOL. XXXIX. No. 1012.

RECENT CONTRIBUTIONS TO THE HISTORY OF DETONATING AGENTS.

By Professor ABEL, C.B., F.R.S.

AMONG the many explosive preparations which have during the last thirty years been proposed as substitutes for gunpowder, on account of greater violence and other special merits claimed for them, not one has yet competed with it successfully as a propelling agent, nor even as a safe and sufficiently reliable explosive agent for use in shells; for industrial applications and for very important military or naval uses, dependent upon the destructive effects of explosives, it has had, however, to give place, to a very important extent, and in some instances altogether, to preparations gun-cotton and nitro-glycerin.

Some of the chief results attained by Mr. Abel's experiments may be briefly summarised.

It was found that the susceptibility to detonation, as initiative detonation, is not confined to gun-cotton, nitrodistinguished from explosion, through the agency of an glycerin, and preparations containing those substances, but that it is shared, though in very different degrees, by all explosive compounds and mixtures.

It was demonstrated that the detonation of nitroglycerin and other bodies, through the agency of an initiative detonation, is not ascribable simply to the direct operation of the heat developed by the chemical changes of the charge of detonating material, and that the remarkable property possessed by the sudden explosion of small quantities of certain bodies (the mercuric and silver fulminates) to accomplish the detonation of nitro-glycerin and gun-cotton, is accounted for satisfactorily by the mechanical force thus suddenly brought to bear upon some part of the mass operated upon. Most generally, therefore, the degree of facility with which the detonation of a But...e appeared little prospect that either gunsubstance will develop similar change in a neighbouring cotton or nitro-glycerin, whether used in their most simple explosive substance, may be regarded as proportionate to conditions or in the forms of various preparations, would the amount of force developed within the shortest period assume positions of practical importance as explosive of time by that detonation, the latter being in fact analoagents of reliable, and therefore uniformly efficient, cha-gous in its operation to that of a blow from a hammer or racter, until the system of developing their explosive force of the impact of a projectile. through the agency of a detonation, instead of through the simple agency of heat, was elaborated.

Before the first step in this important advance in the application of explosive agents was made by Alfred Nobel, about twelve years ago, the very variable behaviour of such substances as gun-cotton and nitro-glycerin, when exposed to the heat necessary for their ignition under comparatively slight modifications of attendant conditions (e.g., as regards the completeness and strength of confinement or the position of the source of heat with reference to the main mass of the material to be exploded) rendered them uncertain in their action, and at any rate, only applicable under circumstances which confined their usefulness within narrow limits. The employment by Nobel of an initiative detonation, produced by the ignition of small quantities of mercuric fulminate or other powerful detonating substances, strongly confined, for developing the violent explosion, or detonation, of nitro-glycerin, opened a new field for the study of explosive substances, and the first practical fruit was the successful application of plastic preparations of nitro-glycerin and of compact forms of compressed gun-cotton, with simplicity and certainty, to the production of destructive effects much more considerable than could be accomplished through the agency of much larger amounts of gunpowder, applied under the most favourable conditions. Whereas very strong confinement has been essential for the complete explosion of these substances, so long as the only known means of bringing about their explosion consisted simply of the application of fire or sufficient heat, no confinement whatever is needed for the development, with certainty, of a decidedly more violent explosive action then they are capable of exerting when thus applied, if the are detonated by submitting some small portion of the nass to the blow or concussion developed by a sharp detonation, such as is produced by the ignition of a small quantity of strongly confined mercuric fulminate.

The conditions essential to the development of detonation in masses of nitro-glycerin and gun-cotton, or preparations of them, and the relations to and behaviour towards each other of these and other explosive bodies, in their character or functions as detonating agents, has been

Abstract of a Paper read before the Royal Institution of Great Britain, Friday, March 21, 1879.

Thus, explosive substances which are inferior to mercuric fulminate in the suddenness, and the consequent momentary violence, of their detonation, cannot be relied upon to effect the detonation of gun-cotton, even when used in comparatively considerable quantities. Percussion cap composition, for example, which is a mixture of fulminate with potassium chlorate, and is therefore much less rapid in its action than the pure fulminate, must be used in comparatively large quantities to accomplish the detonation of gun-cotton.

The essential difference between an explosion and what we now distinguish as a detonation lies in the comparative suddenness of the transformation of the solid or liquid explosive substance into gas and vapour.

The gradual nature of the explosion of gunpowder is illustrated, in its extreme, by burning a train of powder in the open air; the rapidity and consequent violence of the explosion is increased in proportion to the degree of confinement of the exploding, charge, or to the resistance to the escape or expansion of the gases generated upon the first ignition of the confined substance. In proportion as the pressure is increased under which the progressive transformation of the explosive takes place, the rapidity with which its particles are successively subjected to the action of heat is increased.

In the case of a very much more sensitive and rapidly explosive substance than gunpowder, such as mercuric fulminate, the increase in the rapidity of its transformation, by strong confinement, is so great that the explosion assumes the character of a detonation in regard to sudderness and consequent destructive effect. A still more ser.sitive and rapidly explosive material (such as the silver fulminate and iodide of nitrogen) produces when exploded in open air effects akin to those of detonation; yet even with these bodies confinement operates in increasing the rapidity of the explosive to suddenness, and consequently in developing a more purely detonative action. Thus, the violence of explosion of silver fulminate is decidedly ir.creased by confining the substance in a stout metal case, and the enclosure of iodide of nitrogen in a shell of plaster of Paris has a similar effect. With chloride of nitrogen, the suddenness of detonation, and consequently the violence of action, was found to be very greatly increased even by confining the liquid beneath a thin layer of water.

Detonation, developed in some portion of a mass, is

166

End-on Illumination in Private Spectroscopy.

transmitted with a velocity approaching instantaneousness throughout any quantity, and even if the material is laid out in the open air in long trains composed of small masses. The velocity with which detonation travels along trains thirty or forty feet in length, composed of distinc masses of gun-cotton and of dynamite, has been determined by means of Noble's chronoscope, and was found to range from 17,000 to 24,000 feet per second. Even when trains of these explosive agents were laid out with intervening spaces of half an inch between the individual masses composing the trains, detonation was still transmitted along the separated masses with great though diminished velocity.

The suddenness with which detonation takes place has been applied as a very simple means of breaking up shells into small fragments, and scattering these with considerable violence, with employment of very small charges of explosive agent. Thus, by filling a 16-pr. common shell completely with water, and inserting a charge of oz. of gun-cotton fitted to a detonating fuze, the shell being thoroughly closed by means of a screw-plug, the force developed by the detonation of the small charge of gun-cotton is transmitted instantaneously in all directions by the water, and the shell is thus broken up into a number of fragments averaging fourteen times the number produced by bursting a shell of the same size by means of the full amount of powder which it will contain (13 ozs.). Employing 1 oz. of powder in place of oz. of gun-cotton in the shell filled with water, the comparatively very gradual explosion of the powder charge is rendered evident by the result, the shell being broken up into less than twenty fragments by the shock produced by the first ignition of the charge, transmitted by the water. In this case the shell is broken up by the minimum amount of force necessary for the purpose, before the explosive force of the powder charge is properly developed. Extensive comparative experiments, carried on not long since by the Royal Artillery, at Okehampton, demonstrated that this simple expedient of filling common shells with water and attaching a small charge of guncotton with its detonator to the fuze usually employed, allowed of the application as efficient substitutes for the comparatively complicated and costly shrapnel and segment shells.

Another illustration of the sharpness of action developed by detonation as compared with explosion, consequent upon the almost instantaneous character of the metamorphosis which the explosive agent undergoes in the cases of detonation, is afforded by a method which the lecturer applied some years since for comparing the violence of action of charges of gun-cotton and of dynamite arranged in different ways. The charges (5 lbs.) to be detonated were freely suspended over the centres of plates of very soft steel of the best quality, which rested upon the flat face of a massive block or anvil of iron, having a large central circular cavity. The distance between the upper surface of the plate and the charge suspended over it was 4 feet. The sharp blow delivered upon the plate by the air suddenly projected against it by the force of the detonation when the charge was fired forced the metal down into the cavity of the anvil, producing cup-shaped indentations, the dimensions of which afforded means of comparing the violence of the detonation. A much larger charge of powder exploded in actual contact with the plate would produce no alteration of form in the metal, and the same negative result would be furnished by the explosion over the plate of a heap of loose gun-cotton of the same or greater weight than the charges detonated. The above method of experiment was devised, in the first instance, by Mr. Abel, in July, 1875, for comparing the quality of some specimens of Llandore steel proposed to be used by the Admiralty for ship-building purposes with samples of malleable iron, and it has since been employed by Mr. Adamson in carrying out a very useful series of experiments, recently communicated to the Iron and Steel Institute.

(To be continued.)

April 18, 1879. END-ON ILLUMINATION IN PRIVATE SPECTROSCOPY,

AND ITS

APPLICATIONS TO BOTH BLOWPIPE FLAMES
AND ELECTRIC ILLUMINED
GAS-VACUUM TUBES."

By PIAZZI SMYTH,
Astronomer Royal for Scotland, and Past President of R.S.S. Arts.
(Continued from p. 146).

PART II.
Flame-Spectroscopy.

THE various kinds of flame most frequently employed to
render substances incandescent in spectroscopy, are-
(1). The alcohol lamp.

(2.) The Bunsen gas burner.

(3.) The coal-gas blowpipe driven by air.

(4.) The coal-gas blowpipe driven by oxygen. And (5.) The oxy-hydrogen blowpipe.

Of these five kinds, I choose the middle one as a stand by; for while its pointed conical flame is more definite, precise, and workmanlike than the wavy loose flames of the first two, it is cheaper, more usually met with, and more frequenlty ready for acting, than the two latter; while it links us on to a very fair amount of heat for any flame-work, or to what we may consider a standard step in temperature throughout all these researches. The above coal-gas and air blowpipe has, moreover, the further recommendation that, dull as its blue-gray flame may appear to the eye, yet it contains several colours which separate into distinct, discontinuous bands under the spectroscope; and they would probably be more often utilised for spectroscopic science if they could only be made decidedly brighter. But brighter it must be without any change of temparature, and also without our losing the use of the simple open flame to vapourise at pleasure adventitious and external matters in the usual flame spec. troscopic manner.

Prof. Swan of St. Andrews, who first gave a large, scientific and indeed very noble account of this blowpipe flame and its spectrum, and gave it so far back as 1856, was so impressed with the importance of brightening, if possible, its faint bluish light, that he placed three small blowpipes (of his own ingenious making) one behind the other, and looked through all three flames at once. Thereby he was enabled to measure all the the leading details of four out of the really five coloured bands in this spectrum; but failed to see the lines in the first of these several observers in London, Paris, and Manchester as to position, viz., the orange-amber band. After him recurred to single or double blowpipes, but unfortunately in conjunction with pure oxygen gas; for by that emphatic addition, the temparature of their flames was so greatly raised, that they are all necessarily excluded from the present inquiry.

More recently I have obtained a copy fron Paris of the late Padre Secchi's grand work entitled "Le Soleil" (2nd ed. 1875); and on p. 246 of vol. i.,-where that brilliant scientist has introduced, though without acknowledg ment, a copy of my own Edinburgh Observatory sketch in 1872 of the whole five bands of the simple blowpipe spectrum,-he yet, in alluding to it in the text, speaks of the bands as being, in all ordinary cases witnessed by him, three only, and their colours "green and blue "— really citron, green, and blue; in which case he could only have seen the three brighter ones of the five.

In Prof. Roscoe's well-known volume of "Lectures on Spectrum Analysis" (1st ed. 1868), there is a coloured representation of the coal-gas spectrum with five bands, and some of them with lines; not perhaps intended to be very acturate, but most assuredly not indicating the * Read before the Royal Scottish Society of Arts, February 10, 1879.

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