one.

MESSRS. GAUTHIER-VILLARS (Paris) have recently added three new works to their already large list of photographic treatises. One is the "Manuel de Phototypie," by M. Bonnet, giving full details of the various processes for the rapid reproduction of photographs, such as is now demanded for many purposes. The formulæ are stated very clearly, and the apparatus required is sufficiently illustrated by diagrams. The treatise is thoroughly practical, and will be very valuable to all interested in the subject, whether as amateurs or for trade purposes. The second-"Temps de Pose"-is by M. Pluvinel, and deals with the difficult question of the time of exposure. It is shown that what is generally regarded as a rule-of-thumb process can be reduced to a scientific The various functions of the duration of the exposure are first considered mathematically, and it is then shown how the results of the investigations are to be applied practically, the method being illustrated by worked-out examples. To simplify matters, tables are given showing the different elements, such as coefficient of brightness, for all ordinary photographic subjects. The treatise is chiefly interesting as a scientific contribution, as few photographers will care to take the trouble of working out the time of exposure, now that they have found that good work can be done by judgment alone. The third book is in two volumes, and treats of the various "film" processes (" Procédés Pelliculaires," by George Balagny). It claims to give a full account of all that has been said and done in connection with the subject since the introduction of photography, and as far as we can judge, this claim is fully justified. Every detail of the subject is considered in a very practical manner. One of the most interesting applications of flexible films mentioned is the registration of flash signals in "optical telegraphy."

THE "Year-book of Photography " (Piper and Castle) for 1890 fully bears out the good reputation gained by its predecessors. In addition to the information relating to the various photographic societies, there are several articles on the advances in photographic processes which have been made during the past year, and other useful notes. One of the most interesting articles is that by the editor on photography in natural colours, from which we learn that "processes of practical value, to achieve the end, are likely to be discovered by the exercise of ability and perseverance." The only important omission we notice is a record of the remarkable achievements in astronomical photography. The volume contains a portrait and short biographical notice of Edmond Becquerel. The whole forms an invaluable book of reference to all photographic matters, with the exception referred to.

MESSRS. GEORGE BELL AND SONS have published "The School Calendar and Hand-book of Examinations, Scholarships, and Exhibitions, 1890." This is the fourth year of issue, and great pains have been taken, as in former years, to secure that the information brought together shall be full and trustworthy. A preface is contributed by Mr. F. Storr.

THE sixteenth part of Cassell's "New Popular Educator "has been issued. It includes a map of Australasia.

THE Proceedings of the International Zoological Congress, held in Paris last summer, will be ready for distribution in a fortnight.

A NEW and very simple method of synthesizing indigo has been discovered by Dr. Flimm, of Darmstadt (Ber. deut. chem. Ges., No. 1, 1890, p. 57). In studying the action of caustic alkalies upon the monobromine derivative of acetanilide, CH.NH.CO.CH,Br, a solid melting at 131°5, it was found that when this substance was fused with caustic potash a product was obtained which at once gave an indigo blue colour on the addition of water, and quite a considerable quantity of a blue solid resembling indigo separated out. The best mode of carrying out the operation is described by Dr. Flimm as follows:-The

monobromacetanilide is carefully mixed with dry caustic potash in a mortar, and the mixture introduced into a retort and heated rapidly until a homogeneous reddish-brown melt is obtained This is subsequently dissolved in water, and a little ammonia or ammonium chloride solution added, when the liquid immediately becomes coloured green, which colour rapidly changes into a dark blue, and in a short time the blue colouring matter is for the most part deposited upon the bottom of the vessel in which the operation is performed. The fused mass may also conveniently be dissolved in dilute hydrochloric acid, and a little ferric chloride added, when the formation of indigo takes place immediately. The collected blue colouring matter may be readily obtained pure by washing first with dilute hydrochloric acid and afterwards with alcohol. That this blue substance was really common indigo was proved by the fact that it yielded several of the most characteristic reactions of indigotin, such as solubility in aniline, paraffin, and chloroform, its sublimation, and the formation of sulphonic acids, which gave similar changes of colour with nitric acid to those of indigotin. The final proof was afforded by its reduction to indigo white and re-oxidation to indigo blue by exposure to air. Moreover, the absorption spectrum of the colouring matter was found to be identical with the well-known absorption spectrum of indigo. Hence there can be no doubt that indigo is really formed by this very simple process. The chemical changes occurring in the reaction are considered by Dr. Flimm to be the following:- Indigo blue is not produced directly, but first, as a condensation product of the NH monobromacetanilide, indoxyl is formed, CH

CH, or

COH

by oxidation into indigo, CH

CO CO two molecules each losing two atoms of hydrogen by oxidation, and then condensing to form indigo. It was not found possible to isolate the intermediate pseudo-indoxyl, owing to its extreme instability; indeed, the all-important point to be observed in the practical carrying out of the synthesis by this method is that the fusion must be performed quickly and the temperature raised rapidly to a considerable height, the whole process occupying only a few minutes. The yield of pure indigo under the conditions yet investigated is not very large, amounting to about four per cent. of the weight of the original anilide.

THE additions to the Zoological Society's Gardens during the past week include thirteen Cuning's Octodons (Octodon cuningi) from Chili, presented by Mr. W. H. Newman; five Common Dormice (Muscardinus avellanarius), British, presented by Mr. Florance Wyndham; a Large Hill-Mynah (Gracula intermedia) from India, deposited; a Dingo (Canis dingo), born in the Gardens.

Remarks.

(1) The spectrum of this nebula has not yet, so far as I know, been recorded, but the observation will not be difficult, if one may judge from the description given by Herschel, namely: "Very bright, pretty large, round, much brighter in the middle, mottled as if with stars."

(2) This star has a spectrum of the Group II. type, Dunér describing it as very beautiful. He states that all the bands, I-9, are very wide and dark. The observations most likely to extend our knowledge of the group of bodies to which this star belongs are (1) observations of the bright carbon flutings (see p. 305); (2) comparisons with the flame spectra of manganese, magnesium, and lead; (3) observations made with special reference to the presence or absence of absorption lines, of which Dunér makes no mention.

(3) Gothard classes this with stars of the solar type. The usual differential observations are required.

(4) A star of Group IV. The usual observations of the relative intensities of the hydrogen and metallic lines (b, D, &c.), as compared with other stars, are required.

(5) A rather faint star of Group VI., in which the character of band 6 (near λ 564), as compared with the other carbon bands (9 and 10), requires further attention. Secondary bands should also be looked for.

(6) This variable is stated by Gore to have a continuous spectrum, but it seems probable that lines or flutings will be found if the star be examined under the most favourable conditions—that is, when near maximum. Rigel was formerly said to have a "continuous" spectrum, but the lines are now by no means difficult to see. The star ranges from magnitude 6 at maximum to 72 at minimum, and the period is 31-50 days (Gore). A. FOWLER.

TOTAL SOLAR ECLIPSE OF 1886.-Dr. Schuster has thus

summarized the spectroscopic results he obtained at this eclipse (Phil. Trans., vol. 180, 1889) :

(1) The continuous spectrum of the corona has the maximum of actinic intensity displaced considerably towards the red, when compared with the spectrum of sunlight.

(2) While, on the two previous occasions on which photographs of the spectrum were obtained, lines showed themselves outside the limits of the corona, this was not the case in 1886.

(3) Calcium and hydrogen do not form part of the normal spectrum of the corona. The hydrogen lines are visible only in the parts overlying strong prominences; the H and K lines of calcium, though visible everywhere, are stronger on that side of the corona which has many prominences at its base.

(4) The strongest corona line in 1886 was at λ = 42328; this is probably the 42330 line often observed by Young in the chromosphere.

(5) Of the other strong lines, the positions of the following seem pretty well established :

:

4056 7 4084 2 4089 3 4169 7 4195 0 4211.8 4280'6 4365 4 4372 2 4378 1 4485'6 4627'9

The lines printed in thicker type have been observed also at the Caroline Island and Egyptian Eclipses.

(6) A comparison between the lines of the corona and the lines of terrestrial elements has led to negative results.

ANNUAIRE DU BUREAU DES LONGITUDES.-In the volume for 1890, MM. Loewy and Schulhof contribute a list of the comets which appeared from 1825 to 1835 inclusive, and in 1888, being a continuation of the lists given in former years. M. Loewy also gives a complete table of the appearances of the planets throughout 1890, and ephemerides of a considerable number of variable stars. An elaborate comparison of the various calendars is from the pen of M. Cornu, and under the head of the solar system a rich store of information is included. With the notices we find an account of the meeting of the permanent committee of the photographic chart of the heavens and the Photographic Congress of September last. This year's Annuaire is as completely filled with information as it has ever been and doubtless will be as much appreciated by astronomers.

sketch of his predecessor, J. C. Houzeau, which is embellished with the portrait of this deceased bibliographer. Considerable attention has been paid to the researches on diurnal nutation and the determination of the constant. M. Spee discusses the tabulated observations of the condition of the sun's surface during 1888, and M. Moreau contributes an interesting note on the movement of a solid about a fixed point. A list is also given of the comets and asteroids discovered in 1889, and some of the particulars relating to their orbits.

ROYAL ASTRONOMICAL SOCIETY.-The annual general meeting of the Fellows of this Society will be held at Burlington House on Friday, the 14th inst., for the purpose of receiving the Report of the Council, electing officers for the ensuing year, and transacting other business of the Society. The chair will be taken at 3 o'clock precisely.

Erratum.—In the elements of companion C of Brook's comet (p. 305), read 8 = 17° 52′ 24′′ 5, and log a = 0 565059.

GEOGRAPHICAL NOTES.

BARON NORDENSKIÖLD has announced in the Swedish Academy of Sciences, that he and Baron Oscar Dickson, with assistance from the Australian colonies, will start on an expedition in the South Polar regions next year.

A RECENT telegram from Tashkent announced that Colonel Pevtsoff and M. Roborovsky had discovered a convenient pass to the north-western part of Tibet, from Nia, and had mounted to the great table-land. The plateau has there an altitude of 12,000 feet above the sea, and the country round is desolate and uninhabited, while towards the south the plateau is well watered and wooded. The Tashkent telegram is so expressed that it might be supposed to mean that two separate passes had been discovered by the two explorers. But the news received from the expedition at St. Petersburg on December 26, and dated October 27, shows that both explorers proposed to leave the oasis of Keria (100 miles to the east of Khotan) on the next day, for Nia (65 miles further east) and there to search for a passage across the border-ridge which received from Prjevalsky the name of the "Russian ridge." This immense snow-clad chain separates the deserts of Eastern Turkestan from the trapezoidal space, the interior of which is quite unknown yet, and which is bordered by the "Russian” ridge and the Altyn-tagh in the north-west; the ridges of Tsaidam and those named by Prjevalsky"Columbus and " Marco-Polo" in the north-east; the highlands (explored by Prjevalsky in 1879-80) at the sources of the Blue River, in the south-east; and a long, yet unnamed ridge which seems to be a prolongation of the Tan-la, in the south-west. leading to that plateau from Nia, and now discovered by the Russian expedition, is situated some 80 miles to the east of the well-known pass across the Kuen-lun Mountains which leads from Southern Khotan to Lake Yashi-kul. M. Roborovsky's intention is evidently next to move up the Tchertchen river and to endeavour to reach the ridges "Moscow" and "Lake Unfreezing" (11,700 feet high), which were visited by Prjevalsk from the east during his last journey. Having succeeded in finding a pass to Tibet in the south of Nia, Colonel Pevtsoff proposes, as soon as the spring comes, to proceed himself by this pass to the table-land, while M. Roborovsky probably will be despatched to explore the same border-ridge further east, in the south of Tchertchen.

The pass

THE Boletin of the Madrid Geographical Society for the last quarter of 1889 contains a most valuable memoir by Dr. Fernando Blumentritt, on the intricate ethnology of the Philip. pine Islands. The author classifies the whole of the native population in three broad divisions-Negrito, Malay, and Mongoloid; the last comprising those tribes which in their physical appearance betray certain Chinese or Japanese affinities. All are grouped in an admirably arranged alphabetical table, where their names, race, language, religion, culture, locality, and numbers are briefly specified in seven parallel columns. With a few variants and cross-references this table contains no less than 159 entries, and thus conveys in summary form all the essential particulars regarding every known tribe in the Philippine Archipelago. From it we gather that the Negritoes-that is, the true autochthonous element, variously known as Aetas, Atias, Atés, Etas, Itas, Mamánuas, &c., and physically belonging to the same stock as the Samangs of the Malay Peninsula―

are now reduced to about 20,000, dispersed in small groups over the islands of Luzon, Mindoro, Tablas, Panay, Negros, Cebu, Paragan (Palawan), and Mindanao. A few also appear still to survive in Alabat, Busuanga, and Culioú. Of the Malay peoples by far the most numerous and important are the southern Bisayas (Visayas), and the northern Tagalas, both described as "civilized Christians," and numbering respectively 1,700,000 and 1,250,000. These two peoples are steadily encroaching on all the surrounding tribes, causing them to disappear by a gradual process of absorption or assimilation, and the time is approaching when the whole of the islands will be divided into two great nationalities bearing somewhat the same relation to each other that the High German does to the Low German branch of the Teutonic family.

SMOKELESS EXPLOSIVES.1

I.

THE production of smoke which attends the ignition or ex

plosion of gunpowder is often a source of considerable inconvenience in connection with its application to naval or military purposes, its employment in mines, and its use by the sportsman, although occasions not unfrequently arise during naval and military operations when the shroud of smoke produced by musketry or artillery fire has proved of important advantage to one or other, or to both, of the belligerents during different periods of an engagement.

Until within the last few years, however, but little, if any, thought appears to have been given to the possibility of dispensing with or greatly diminishing the production of smoke in the application of fire-arms, excepting in connection with sport. The inconvenience and disappointment often resulting from the obscuring effects of a neighbouring gun-discharge, or of the first shot from a double-barrel arm, led the sportsman to look hopefully to gun-cotton, directly after its first production in 1846, as a probable source of greater comfort and brighter prospects in the pursuit of his pastime and in his strivings for success.

A comparison between the chemical changes attending the burning, explosion, or metamorphosis of gun-cotton and of gunpowder, serves to explain the cause of the production of smoke in the latter case, and the reason of smokelessness in the case of gun-cotton. Whilst the products of explosion of the latter consist exclusively of gases, and of water which assumes the transparent form of highly-heated vapour at the moment of its production, the explosive substances classed as gunpowder, and which consist of mixtures of saltpetre, or another nitrate of a metal, with charred wood or other carbonized vegetable matter, and with variable quantities of sulphur, furnish products, of which very large proportions are not gaseous, even at high temperatures. Upon the ignition of such a mixture, these products are in part deposited in the form of a fused residue, which constitutes the fouling in a fire-arm, and are in part distributed, in an extremely fine state of division, through the gases and vapours developed by the explosion, thus producing smoke.

and sulphur employed in their production exhibit slight differences in different countries, and these, as well as the character of the charcoal used, its sources and method of production, underwent but little modification for very many years. The same remark applies to the nature of the successive operations pursued in the manufacture of black powder for artillery purposes in this and other countries.

The replacement of smooth-bore guns by rifled artillery which followed the Crimean war, and the increase in the size and power of guns consequent upon the application of armour to ships and forts, soon called for the pursuit of investigations having for their object the attainment of means for variously modifying the action of fired gunpowder, so as to render it suitable for the different calibres of guns, whose full power could not be effectively, or in some instances safely, developed by the use of the kind of gunpowder previously employed indiscriminately in artillery of all known calibres.

In order to control the violence of explosion of gunpowder, by modifying the rapidity of transmission of explosion from particle to particle, or through the mass of each individual particle, of which the charge of a gun is composed, the accomplishment of the desired results was, in the first instance, and indeed throughout practical investigations extending over many years, sought exclusively in modifications of the size and form of the individual masses composing a charge of powder, and of their density and hardness, it being considered that, as the proportions of saltpetre, charcoal, and sulphur generally employed in the production of gunpowder very nearly correspond to those required for the development of the greatest chemical energy by those incorporated materials, it was advisable to seek for the attainment of the desired results by modifications of the physical and mechanical characters of, rather than by any modification in the proportions and chemical characters of, its ingredients.

The varieties of powder, which, as the outcome of careful practical and scientific researches in this direction, have been introduced into artillery service from time to time, and some of which, at any rate, have proved fairly efficient, have been of two distinct types. The first of these, produced by breaking up

more or less highly-pressed cakes of black powder into grains, pebbles, or boulders, of approximately uniform size and shape, the sharp edges and rough surfaces being afterwards removed by attrition (reeling and glazing), are simply a further development of one of the original forms of granulated or corned powder, represented by the old F. G., or small arms, and L. G., or cannon powder. Gunpowder of this class, ranging in size from about 1000 pieces to the ounce, to about six pieces to the pound, have been introduced into artillery service, and certain of them, viz. R. L. G. (rifle large grain), which was the first step in advance upon the old cannon-powder (L. G.); pebble-powder (P.), and large pebble or boulder-powder (P. 2), are still employed more or less extensively in some guns of the present day.

The other type of powder has no representative among the more ancient varieties; it has its origin in the obviously sound theoretical view that uniformity in the results furnished by a particular powder, when employed under like conditions, demands not merely identity in regard to composition, but also identity in form, size, density, and structure of the individual masses composing the charge used in a gun. The practical realization of this view should obviously be attained, or at any rate approached, by submitting equal quantities of one and the same mixture of ingredients, presented in the form of powder of

With other explosives, which are also smoke-producing, the formation of the smoke is due to the fact that one or other of the products, although existing as vapour at the instant of its develop ment, is immediately condensed to a cloud composed of minute liquid particles, or of vesicles, as in the case of mercury vapour liberated upon the explosion of mercuric fulminate, or of the aqueous vapour produced upon the ignition of a mixture of ammonium nitrate and charcoal, or ammonium nitrate and picric acid.

Until within the last half-dozen years, the varieties of gunpowder which have been applied to war purposes in this and other countries have exhibited comparatively few variations in chemical composition. The proportions of charcoal, saltpetre,

Friday Evening Discourse delivered by Sir Frederick Abel, F. R.S., at the Royal Institution of Great Britain, on January 31, 1890.

period in moulds of uniform size, and under surrounding conditions as nearly as possible alike. The fulfilment of these conditions would, moreover, have to be supplemented by an equally uniform course of proceeding in the subsequent drying and other finishing processes to which the powder-masses would be submitted.

The only form of powder, introduced into our artillery service for a brief period, in the production of which these conditions were adhered to as closely as possible, was a so-called pellet powder, which consisted of small cylinders having semi-perforations with the object of increasing the total inflaming surface of the individual masses.

Practical experience with this powder, and with others prepared upon the same system, but with much less rigorous regard to uniformity in such details as state of division and condition of dryness of the powder before its compression into cylindrical or other forms, showed that uniformity in the ballistic properties

of black powder could be as well and even more readily secured by the thorough blending or mixing together of batches presenting some variation in regard to density, hardness, or other features, as by aiming at an approach to absolute uniformity in the characters of each individual mass composing a charge.

At the time that our attention was first actively given to this subject of the modification of the ballistic properties of powder, it had already been to some extent dealt with in the United States by Rodman and Doremus, and the latter was the first to propose the application, as charges for guns, of powder-masses produced by the compression of coarsely grained powder into moulds of prismatic form. In Russia the first step was taken to utilize the results arrived at by Doremus, and to adopt a prismatic powder for use in guns of large calibre.

Side by side with the development and perfection of the manufacture of prismatic powder in Russia, Germany, and in this country, new experiments on the production of powdermasses suitable, by their comparatively gradual action, for employment in the very large charges required for the heavy artillery of the present day, by the powerful compression of mixtures of more or less finely broken up powder-cake into masses of greater size than those of the pebble, pellet, and prism powders, were actively pursued in Italy, and also by our own Government Committee on Explosives, and the outcome of very exhaustive practical investigations were the very efficient Fossano powder, or poudre progressif, of the Italians, and the boulder and large cylindrical powders known as P2 and C, produced at Waltham Abbey, which scarcely vied, however, with the Italian powder in the uniformity of their ballistic properties.

Researches carried out by Captain Noble and the lecturer some years ago with a series of gunpowders differing considerably in composition from each other, indicated that advantages might be secured in the production of powders for heavy guns by so modifying the proportions of the constituents (e.g. by considerably increasing the proportion of charcoal and reducing the proportion of sulphur) as to give rise to the production of a much greater volume of gas, and at the same time to diminish the heat developed by the explosion.

These researches served, among other purposes, to throw considerable light upon the cause of the wearing or erosive action of powder-explosions upon the inner surface of the gun, which in time may produce so serious a deterioration of the arm as to diminish the velocity of projection considerably, and so affect the accuracy of shooting, a deterioration which increases in extent in an increasing ratio to the size of the guns, in consequence, obviously, of the large increase in the weight of the charges fired. Several causes undoubtedly combine to bring about the wearing away of the gun's bore, which is especially great where the products of explosion, while under the maximum pressure, can escape between the projectile and the bore of the gun. The great velocity with which the very highly heated gaseous and liquid (fused solid) products of explosion sweep over the heated surface of the metal gives rise to a displacement of the particles composing it, which increases as the surface becomes roughened by the first action upon the least compact portions of the metal, and thus opposes greater resistance; at the same time, the effect of the high temperature to which the surface is raised is to reduce its rigidity and power of resisting the force of the gaseous torrent, and lastly some amount of chemical action upon the metal, by certain of the highly heated non-gaseous products of explosion, contributes towards an increase in the erosive effects. A series of careful experiments made by Captain Noble with powders of different composition, and with other explosives, afforded decisive evidence that the material which furnished the largest proportion of gaseous products, and the explosion of which was attended by the development of the smallest amount of heat, exerted least erosive action.

It is probable that important changes in the composition of powders manufactured by us for our heavy guns would have resulted from those researches, but in the meantime, two eminent German gunpowder manufacturers had occupied themselves independently, and simultaneously, with the important practical question of producing some more suitable powder for heavy guns than the various new forms of ordinary black powder, the rate of burning of which, especially when confined in a close chamber, was, after all, reduced only in a moderate degree by the increase in the size of the masses, and by such increase in their density as it was practicable to attain. The

66

cocoa

German experimenters directed their attention not merely to the proportions in which the powder ingredients are employed, but also to a modification in the character of charcoal, and the success attending their labours in these directions led to the practically simultaneous production, by Mr. Heidemann at the Westphalia Powder Works, and Mr. Düttenhofer at the Rottweil Works near Hamburg, of a prismatic powder of cocoabrown colour, consisting of saltpetre in somewhat higher proportion, of sulphur in much lower proportion, than in normal black powder, and of very slightly burned charcoal, similar in composition to the charcoal (charbon roux) which Violette, a French chemist, first produced in 1847 by the action of superheated steam upon wood or other vegetable matter, and which he proposed for employment in the manufacture of sporting powder. These brown prismatic powders (or powders,' as they were termed from their colour), are distinguished from black powder not only by their appearance, but also by their very slow combustion in open air, by their comparatively gradual and long-sustained action when used in guns, and by the simple character of their products of explosion as compared with those of black powder. As the oxidizing ingredient, saltpetre, is contained, in brown or cocoa powder, in larger proportion relatively to the oxidizable components, sulphur and charcoal, than in black powder, these become fully oxidized, while the products of explosion of the latter contain, on the other hand, larger proportions of unoxidized material, or only partially oxidized products. Moreover, there is produced upon the explosion of brown powder a relatively very large amount of water-vapour, not merely because the finished powder contains a larger proportion of water than black powder, but also because the very slightly charred wood or straw used in the brown powder is much richer in hydrogen than black charcoal, and therefore furnishes by its oxidation a considerable amount of water. The total volume of gas furnished by the brown powder (at o° C. and 760 mm. barometer) is only about 200volumes per kilogramme of powder, against 278 volumes furnished by a normal sample of black powder, but the amount of water-vapour furnished upon its explosion is about three times that produced from black powder, and this would make the volume of gas and vapour developed by the two powders about equal if the heat of its explosion were the same in the two cases; the actual temperature produced by the explosion of brown powder, is, however, somewhat the higher of the two.

Although the smoke produced upon firing a charge of brown powder from a gun appears at first but little different in denseness to that of black powder, it certainly disperses much more rapidly, a difference which is probably due to the speedy absorption, by solution, of the finely divided potassium salts by the large proportion of water-vapour distributed throughout the socalled smoke.

This class of powder was substituted with considerable advantage for black powder in guns of comparatively large calibre; nevertheless it became desirable to attain even slower or more gradual action in the case of the very large charges required for guns of the heaviest calibres, such as those which propel shot of about 2000 pounds weight. Accordingly, the brown powder has been modified in regard to the proportions of its ingredients to suit these conditions, while, on the other hand, powder intermediate with respect to rapidity of action between black pebble powder and the brown powder, has been found more suitable than the former for use in guns of moderately large calibre.

The recent successful adaptation of machine guns and comparatively large quick-firing guns to naval service, more especially for the defence of ships against attack by torpedo boats, &c., has rendered the provision of a powder for use with them, which would produce comparatively little or no smoke, a matter of very considerable importance, inasmuch as the efficiency of such defence must be greatly diminished by the circumstance that, after a very brief use of the guns with black powder, the objects against which their fire is destined to operate, become more or less completely hidden from those directing them, by the dense veil of powder-smoke produced. Hence much attention has been directed during the last few years to the production of smokeless, or nearly smokeless powders for naval use in the above directions. At the same time, the views of many military authorities regarding the importance of dispensing with smoke in land engagements has also created a demand, the apparent urgency of which has been increased by various circumstances,