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THE CHEMICAL NEWS

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NEWS,

per litre, Dr. Pavy's proportion holds strictly good, and . then further addition of alkali again increases the oxidising

power of the copper solution, but in much smaller pro

portion than before. VOL. XXXIX. No, 1015.

I further gradually diminished the alkali in the copper solution by adding measured quantities of standard acid, the results being as follow : Pavy Solution.

Sugar Solution. AN EXAMINATION OF DR. PAVY'S METHOD OF 100 c.c. -020 NaHO required 11'00 c.c. DETERMINING GLUCOSE.

-0.40

10'71 15 -0.60

10'42 By OTTO HEHNER, F.C.S., F.I.C.

Thus it appears that the smaller the quantity of fixed The glowing account given by Dr. Pavy (CHEMIC.IL alkali, the smaller also the amount of sugar the copper News, vol. xxxix., p. 77) of the results obtained in deter. solution is capable of oxidising; in fact, when no caustic mining glucose by means of ammoniated Fehling solution soda at all is present, as in the last of the above experihas doubtless induced many chemists to repeat Dr. Pavy's ments, i molecule of glucose requires exactly 8 molecules experiments and to test the accuracy of his method. of cupric oxide for oxidation. With ordinary Fehling

120 c.c. of ordinary Fehling solution are mixed with solution the ratio is 5 molecules; with the same rendered 300 c.c. of strong ammonia (sp. gr. o.88) and diluted to ammoniacal and containing no less than 120 grms. NaHO 1000 c.c. 100 c.c. of this liquid, containing 12 c.c. per litre, 6 molecules; and, lastly, the same without soda, Fehling solution and capable of oxidising, according to 8 molecules. But the reaction without fixed alkali takes Dr. Pavy, 0.05 grm. glucose, were used in the following place exceedingly slowly, and on that account the end. experiments instead of 40 c.c., as recommended by Dr. | point is not easy to hit off. Pavy, in order to obtain results comparable without cal. Instead, therefore, of guarding against too large a culation with those furnished by io c.c. of ordinary quantity of alkali, it is of far greater importance to avoid Fehling solution. The mode of titration was precisely a deficiency, and good results can only be obtained by that described by Dr. Pavy.

doubling the quantity of soda usually taken in the preFollowing thus Dr. Pavy's directions I was surprised to 1 paration of the cupro-tartrate solutior.. On the other obtain results widely differing from his, inasmuch as in a hand, a much smaller excess of soda influences the result long series of experiments I found a difference of about than is stated by Dr. Pavy, who found an addition of 8 per cent in the total amount of glucose when deter 5 grms. to 100 c.c. of the ammoniacal solution, or 417 grms. mining it both by the ordinary copper solution and by to the litre of Fehling solution without influence, whilst the same rendered ammoniacal, the latter furnishing the my results, which I have verified over and over again, higher results. In order to obtain corresponding results show that even 2 grms. to 100 c.c. of the ammoniated I had to dilute about 130 c.c. of Fehling solution with solution, or 166 to the litre of Fehling, show a small but ammonia and water to 1000 c.c., instead of 120 c.c. as quite perceptible alteration. Thus the limits of alkali found by Dr. Pavy.

allowable or necessary are not so wide as might appear. The copper solution used in these experiments con- If the proportions given by me are adhered to, the tained 400 c.c. of soda solution (of 1:14 sp. gr.) per litre, method is capable of furnishing excellent results. The and the sugar solution (inverted sugar) was quite neutral; solution containing the glucose should be added drop by hence there could not possibly be too large a quantity of drop to the ammoniacal copper solution, kept gently alkali, against which Dr. Pavy warned in his paper. simmering. The end-point of the reaction is beautifully

I then prepared another quantity of Fehling solution, sharp, and titrations of the same liquid will never differ by employing 480 c.c. soda, as recommended by Fresenius. more than o'I C.C. of the sugar solution. The action is, I tested this both without and with the addition of am- however, somewhat slower than with ordinary Fehling monia, by titration with an invert sugar solution, obtained | liquid. By suitable arrangements the ammonia can by heating 1'0153 gims. pure cane-sugar dissolved in readily be absorbed and any nuisance avoided which would 150 c.c. of water, with 10 c.c. strong HCl, on the water | result from its entering the atmosphere. bath, neutralising, and diluting to 250 c.c.

It must not, however, be taken for granted that the 10 c.c. of Fehling solution required 11•70 c.c. sugar ratio holding good between the ordinary and the amsolution.

moniated copper solution is valid also in the case of other 10 c.c. Fehling + 1 grm. NaHO used 11•65 c.c. sugar reducing saccharine matters. Dextrose and lævulose act solution.

equally, but I find that both milk sugar and maltose

possess entirely different reducing power against two " Pavy Solution."

Sugar Solution.

kinds of copper solutions.
100 C.C. used
11°22 .C.

Thus a solution of pure milk-sugar acted as follows: +0:2 grm. NaHO 11'40 1

IO C.C. ordinary Fehling solution required 1676 c.c. 0°4

11°55 0.6

IOO C.C. Pavy solution

in 20°76 , 0.8 11°70 ,

The ratio is therefore just contrary to that resulting by Io 11°72 10

the action of glucose. The titration of milk-sugar, diffi2'0 II'90,

cult and unsatisfactory as it is with the ordinary Fehling 3'0 12'08 ,

test, is, however, still more readily influenced by dilution,

quantity of alkali, and rate of addition, and hence still The results show quite conclusively that Fehling solu. less trustworthy in ammoniacal solution. Its action on tion prepared with 480 c.c. of soda of l'14 sp. gr., corre

that solution is very slow, and the end-point is somewhat sponding to about 68 grms. NaHO per litre, does not give difficult to observe, because on the experiment being much results concordant with the ratio stated by Dr. Pavy, and protracted cuprous oxide deposits and obscures the colour also that additions of very small quantities of soda of the liquid. steadily but perceptibly alter that ratio, until 50 grms. of Maltwort acts similarly to milk-sugar, proving that it soda per litre have been added to that already contained does not contain glucose, but another sugar, doubtless in the liquid, when further addition of soda, up to more maltose. Experiments in reference to this matter are in than 80 grms., is without influence. Between these progress. limits, namely with a total of 120 to 150 grms. of soda 54, Holborn Viaduct, London, April 12.

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198
History of Detonating Agents. . .

CHEMICAL NEWS,

1 May 9, 1879. RECENT CONTRIBUTIONS TO THE HISTORY | thicknesses, with a Martini-Henry rifle, at short ranges, OF DETONATING AGENTS.

afforded interesting confirmation of the correctness of the

explanation given of the operation of a blow upon masses By Professor ABEL, C.B. F.R.S.

of explosive material under different conditions. Disks of (Continued from p. 183.)

gun-cotton of the same density and diameter, but differing

in thickness, were fired at; they were freely suspended, It will now be evident why the readily yielding nature

and their distance from the marksman was in all instances of the particles of liquid nitro-glycerine tends to counteract

100 yards. The thinnest disks were simply perforated by its great sensitiveness to detonation, and why, when the

the bullets, not a particle of the gun-cotton being ignited. motion of the liquid particles is impeded by their admix

Somewhat thicker disks were infamed by the impact of ture with solid matter. and when they are consequently the bullet, while still thicker disks, fired at under the same placed in a position to resist mechanical motion by the

conditions, were exploded, portions being in some instances force applied through the agency of detonation, its natural

dispersed in a burning state. No instance of detonation sensitiveness to detonation, and the rapidity with which

was, however, obtained. These differences in effect, ob. it can be transmitted from particle to particle became fully

tained with masses of different thickness and weight, are developed.

due to the difference in their power to resist mechanical Again, the reduction of gun-cotton fibre to a fine state

I motion when struck by the bullet, and in the different of division, which renders the material readily convertible am

amount of resistance to penetration presented by the thin

and the thicker disks. into very compact and dense masses, places the particles

! in the condition most favourable to resist mechanical

It has been explained that nitro-glycerin may be largely motion upon the application of a blow, or of the concussion

diluted with inert solid matters without the sensitiveness resulting from a detonation; hence, compressed gun-cotton is readily susceptible of detonation in proportion to the

air becomes very much facilitated, because the mobility of extent of compression, or to its density and compactness,

the particles, and their consequent tendency to yield to while loose gun-cotton wool, or the lightly twisted or com

the force of a blow or detonation, is very greatly dimi, pressed material, cannot be readily detonated, because the

nished. But if a solid explosive agent is diluted with inert force applied is expended in imparting motion to the readily

solid matter the case is different; for in such a mixture of yielding particles of the mass. If the force applied through

the finely divided solid with non-explosive solid particles, the agency of a detonator to a mass of explosive material

there must be a partial and sometimes a complete separajust borders upon that required for the development of the

tion of the particles of the explosive by the interposed inert detonation, or if the condition of the mass is such as

particles with which it is diluted; hence the sensitiveness hardly to present the requisite resistance to mechanical

to detonation is reduced, and its transmission by the par. motion essential for its detonation, then results interme.

ticles is retarded or altogether impeded, by a diminution diate between the mechanical dispersion of the mass and

of the extent of contact between the substance to be deits violent chemical dispersion or disintegration, i.e., de.

tonated and the initiative detonation, and by the barrier tonation, are obtained. Thus frequent instances have been

which the interposed non-explosive particles oppose to the observed, especially in the experiments in the transmission

transmission of detonation. Thus a mixture of mercuric of detonation through tubes, in which the initiative deto.

fulminate with more than one-fifth its weight of French

chalk could not be detonated by means of one grain of nation has brought about an explosion attended with little, if any, destructive effect, portions of the mass being at the

pure fulminate enclosed in a copper capsule, which was same time dispersed and occasionally inflamed. Not only

inserted into the mixture; that quantity, similarly con. have such results often been obtained with gun-cotton and

fined, sufficed to detonate undiluted fulminate through a dynamite, but even mercuric fulminate, exposed to the

tube 8 inches long and 0.5 inch in diameter. In experi. concussion of a distant detonation transmitted through a

ments made in this direction with finely divided gun.cotton, tube, has frequently been exploded in a manner quite dis.

| it was found that although dilution was an inert solid,

I applied in the solid form, reduced the sensitiveness of the tinct from the violent detonation developed in other in. stances. Silver fulminate, which under conditions deto

material to detonation, this was not the case when it was nates violently, even when only a particle of the mass is

incorporated with a salt soluble in water, the mixture subjected to a sufficient disturbing influence, has been ex

being then compressed while in the wet state. The comploded without the usual demonstrations of force, by the

pressed masses thus obtained were, when dried, in a condi. transmitted effect of a detonation of mercuric fulminate.

tion of greater rigidity than could be attained by submitting In these instances the violence of the concussion produced

| undiluted gun-cotton to considerably more powerful pres. by the initiative detonation was only just bordering on that

sure, because the crystallisation of the soluble salt used as required for the development of detonation, and it appears

the diluent upon evaporation of the particles, cemented probable that only some small portion of the mass operated

į the particles composing the mass more rigidly together. upon was in a condition or position favourable to the action

The gun-cotton was therefore presented in a form more of the initiative blow. The remainder of the mass would

capable of resisting the mechanical action of a small then be dispersed by the gases developed from the detonated

charge of fulminate than a more highly compressed un. portion; in some instances the particles would be in.

diluted gun.cotton, and hence the reduction in sensi. flamed at the moment of their dispersion, in others they

tiveness due to the detonation of the explosive compound would even escape ignition. The latter appears to be

| is nearly counterbalanced by the greater rigidity imparted always the case when gun-cotton is exploded by a blow

to the mass. If a soluble oxidising agent (a nitrate or from a hammer or falling weight. However carefully the

chlorate) be employed as the diluting material, the prearrangements are adjusted with a view to distribute such

disposition to chemical reaction between it and the gun. a blow uniformly over the entire mass struck, the concen.

cotton (which is susceptible of some additional oxidation), tration of a preponderance of the force applied upon some

appears to operate in conjunction with the effect of the portion or portions of the entire mass, appears almost

salt in imparting rigidity to the mixture, thus rendering inevitable; hence only a small portion is actually detonated,

the latter quite as sensitive to the detonating action of the remainder being instantaneously dispersed by the gases

the minimum fulminate charge as undiluted gun-cotton. suddenly generated while the weight is still resting upon

Moreover, the interesting fact has been conclusively esta. the support.

blished that these compressed mixtures of gun-cotton with Some experiments made in firing at masses of com.

a nitrate or a chlorate are much less indifferent to the pressed gun-cotton, differently arranged and of different

influence of detonating nitro-glycerin than gun-cotton

in its pure state. Chlorated and nitrated gun-cotton are * Abstract of a Paper read before the Royal Institution of Great

detonated with certainty by means of oz. of nitroBritain, Friday, March 21, 1879.

glycerin, wliereas the detonation of 2 ozs. of the latter

accomplished the detonation of ordinary compressed gun- gun-cotton from time to time as the exterior becomes sus. cotton only once in a large number of experiments. ficiently dry to inflame ; and in this way a piece of com

If compressed gun-cotton is diluted by impregnating pressed gun-cotton will burn away very gradually indeed. the mass with a liquid, or with a solid which is intro. A pile of boxes containing in all 6 cwts. of gun-cotton, duced into the mass in a fused state, its susceptibility of impregnated with about 20 per cent of water, when surdetonation is reduced to a very much greater extent rounded by burning wood and shavings in a wooden than by a corresponding quantity of a solid inert body, building, was very gradually consumed, the gun-cotton incorporated as such with the gun-cotton, the cause being burning as already described when the surfaces of the the converse of that which operates in preventing a remasses became partially dried. In two other experiments duction of the sensitiveness to detonation of nitro-glycerin quantities of wet gun-cotton of 20 cwts. each, packed in by its dilution with an inert solid. In this case the ex. one instance in a large, strong wooden case, and, in the plosive liquid envelopes the solid diluent, and remains other, in a number of strong packing cases, were placed continuous throughout, occupying the spaces which exist in small magazines, very substantially constructed of conbetween the solid particles ; hence detonation is readily crete and brickwork. Large fires were kindled around the established and transmitted. But in the case of the solid packages in each building, the doors being just left ajar. explosive, the diluent, which is liquid, or at any rate is The entire contents of both buildings had burned away, introduced into the mass in the liquid state, envelopes without anything approaching explosive action, in less each particle of the solid, so that a film of inert material than two hours. This comparatively great safety of wet surrounds each, isolating it from its neighbours, and gun-cotton, coupled with the fact that its detonation in thus opposing resistance to the transmission of detona that condition may be readily accomplished through the tion, which is proportionate to the original porosity or agency of a small quantity of dry gun-cotton, which, absorbent power of the mass.

through the medium of a fulminate fuze or detonator, is While compressed gun-cotton, in the air-dry state, is made to act as the initiative detonating agent, gives to detonated by 2 grains of mercuric fulminate imbedded in gun-cotton important advantages over other violent exthe material, its detonation by 15 grains, applied in the plosive agents for purposes which involve the employment same manner, becomes doubtsul when it contains 3 per of more or less considerable quantities at one time, on cent of water, over and above the 2 per cent which exists account of the comparative safety attending its storage normally in the air-dry substance. Specimens which had and the necessary manipulation of it. Moreover, it has been impregnated with oil or soaked in melted fat and been well established by experiments of many kinds allowed to cool could not be detonated by means of 15 carried out on a considerable scale, as well as by accurate grains of fulminate. These diluted samples of gun-cotton scientific observations, that the detonation of wet guncould only be detonated by adding very considerably to cotton is decidedly sharper or more violent than that of the power of the initiative detonation; 100 grains of the dry material; a circumstance which affords an inte. confined fulminate generally failed to detonate gun.cotton resting illustration of the influence exerted by the physical containing from 10 to 12 per cent of water, and if the condition of the mass upon the facility with which detoamount reached 17 per cent, 200 grains of fulminate were nation is transmitted from particle to particle. In the needed to ensure its cletonation.

determinations made by means of the Noble chronoscope, But moist or wet compressed gun-cotton is decidedly ! of the velocity with which detonation is transmitted along more susceptible of detonation by (dry) compressed gun- layers or trains of gun-cotton and nitro-glycerin, the cotton itself than by mercuric fulminate.

lecturer has included experiments with gun-cotton conThus 100 grains of dry gun-cotton, detonated through taining different proportions of water. When the matethe agency of the ordinary fulminate fuze, suffice to detorial contained 15 per cent of the liquid, some indications nate wet gun-cotton containing 17 per cent of water, were obtained that the rate of transmission of detonation though this result is somewhat uncertain. If the diluting was a little higher than with dry gun-cotton; the differagent amounts to 20 per cent, detonation is not certainence was very decidedly in favour of wet gun-cotton, when with less than I oz. of dry gun-cotton, and if the com- the latter was thoroughly saturated with water. (With pressed material be completely saturated with water (i.e., air-dry gun-cotton the mean rate of transmission ranged containing 30 to 35 per cent) 4 ozs. of the air-dry sub in several experiments between 17,000 and 18,900 feet per stance, applied in close contact, are needed to ensure its second; with gun-cotton containing about 30 per cent of detonation.

water, the mean rate of transmission ranged between Detonation is transmitted through tubes from dry com 19,300 and 19,950 feet per second.) The air in the masses pressed gun-cotton to a moist disk of the material with of compressed gun-cotton being replaced entirely by the the same facility as to the dry substance; and this is also comparatively incompressible body, water, the particles of the case with regard to the propagation of detonation from explosive are in a much more favourable condition to reone mass of moist gun-cotton to another, in open air, all sist displacement by the force of the detonation, and the pieces being ranged in a row, in contact with each hence they are more readily susceptible of sudden chemical other, provided that the piece first detonated does not disintegration. Moreover, the variations in the rate of contain less water than the others to which detonation travel of detonation in dry gun-cotton, resulting from is transmitted. Some curious results, obtained in experi differences in the compactness or rigidity of different ments on the transmission of detonation, with gun-cot-, masses of the material, are very greatly reduced, if not ton containing different proportions of water, appeared to

roportions of water, appeared to entirely eliminated, by saturating the disks with water indicate that the character or quality of detonation deve. and thus equalising their power of resisting motion by a loped by gun-cotton is subject to modification by the pro- sudden blow. portion of water which the latter contains.

Another striking illustration of the influence which the Gun-cotton containing 12 to 14 per cent of water is physical character of an explosive substance exercises ignited with much difficulty on applying a highly heated over its susceptibility to detonation and the degree of body. As it leaves the hydraulic press upon being con- | facility with which its full explosive force is developed, verted from the pulped state to masses having about the is furnished by one of the most recently devised, and one density of water, it contains about 15 per cent of water; l of the most interesting of existing, explosive agents. in this condition it may be thrown on to a fire or held in a Twelve years ago, soon after the process of producing flame without exhibiting any tendency to burn; the masses compressed and granulated gun-cotton had been elabomay be perforated by means of a red-hot iron or with a rated by the lecturer, it occurred to him to employ these drilling tool, and they may with perfect safety be cut into forms of gun-cotton as vehicles for the application of nitroslices by means of saws revolving with great rapidity. It glycerin. A considerable proportion of the liquid was placed upon a fire and allowed to remain there, a feeble absorbed by the porous masses of gun-cotton, and a nitroand transparent flame flickers over the surface of the wet I glycerin preparation analogous in character to dynamite was

200

Electric Lighting Apparatus at the Royal Albert Hall.

CHEMICAL NEWS,

thus obtained. The absorbent was in this case a violently

EXHIBITION OF ELECTRIC LIGHTING explosive body instead of an inert solid as in lynamite,

APPARATUS AT THE ROYAL ALBERT HALL. but the quantity of nitro-glycerin in a given weight of the preparation (to which the name of Glyozilin was given), was considerably less than in the Kieselguhr-pre. paration ; hence the latter was nearly on a point of

On Wednesday evening last an Exhibition of Electric equality with it, in regard to power, as an explosive

Lighting Apparatus at the Royal Albert Hall was in.

augurated by a lecture on the electric light, which was agent,

given by Mr. W. H. Preece, M.Inst.C.E., in the presence of Nobel has observed that if, instead of making use of

the Prince of Wales, the Duke of Edinburgh, Prince the most explosive form of gun-cotton, or trinitro-cellulose,

Christian, and the Duke of Teck. Among the visitors a lower product of nitration of cellulose (the so-called soluble or collodion gun-cotton) is added to nitro-glycerin,

were Lord Lindsay, Lord Rayleigh, Sir F. Pollock, Sir

Charles Bright, Dr. Lyon Playfair, C.B., F.R.S., Dr. the liquid exerts a peculiar solvent action upon it, the

De la Rue, F.R.S., Prof. Tyndall, F.R.S., Prof. Abel, C.B., fibrous material becoming gelatinised while the nitroglycerin becomes at the same time fixed, the two sub

F.R.S., Dr. William Siemens, F.R.S., Dr. Frankland,

F.R.S., Mr. Crookes, F.R.S., Mr. J. N. Lockyer, F.R.S., stances furnishing a product having almost the characters of a compound. By macerating only from 7 to 10 per cent

Prof. Ayrton, &c. of soluble gun-cotton with go to 93 per cent of nitro

After the Prince of Wales had taken a seat on the right glycerin, the whole becomes converted into an adhesive of the orchestra, the Duke of Edinburgh advarced to the plastic material, more gummy than gelatinous in charac

front of the platform, and as Senior Vice-President of the ter, from which, if it be prepared with sufficient care,

Council of the Albert Hall introduced the Lecturer, who no nitro-glycerin will separate even by its exposure to began by demonstrating that all systems of artificiai illuheat in contact with bibulous paper, or by its prolonged mination are dependent upon the production of heat. Some immersion in water, the components being not easily sus. | brilliant experiments were introduced to show that the ceptible of separation even through the agency of a sol. greatest concentration of heat can be produced by electric vent of both. As the nitro-glycerin is only diluted with

currents in overcoming resistance. When this resistance a small proportion of a solidifying agent which is itself an

is the air itself the electric arc is the result: when it is a explosive (though a somewhat feeble one), this blasting wire or carbon rod we have light by incandescence. The gelatine, as Nobel has called it, is more powerful not discussion at the present time was whether light by the only than dynamite but also than the mixture of a smaller arc or by incandescence is to be the light of the future. quantity of nitro-glycerin with the most explosive gun. The arc gives two and a half times the intensity of light cotton, as the liquid substance is decidedly the most given by incandescence by the same power. Mr. Preece violent explosive of the two. Moreover, as nitro-glycerin showed that the improved methods now employed for the contains a small amount of oxygen in excess of that reproduction of electricity by mechanical means is due to the quired for the perfect oxidation of its carbon and hydrogen development of Faraday's discovery that electric currents constituents, while the soluble gun-cotton is deficient in are produced by the rapid rotation of coils of wire in a the requisite oxygen for its complete transformation into powerful magnetic field, Faraday's original apparatus for thoroughly oxidised products, the result of an incorporation showing this being exhibited by the Royal Institution. The of the latter in small proportion with nitro-glycerin is electric light dependent on incandescence was practically the production of an explosive agent which contains the illustrated by the lamps of Werdermann and the Angloproportion of oxygen requisite for development of the American Light Company. That dependent on the arc maximum of chemical energy by the complete burning of was shown by the regulators of Serrin, Siemens, Rapiefi, the carbon and hydrogen, and hence this blasting gelatin

and Wallace. The form of light based on the arc, but should, theoretically, be even slightly more powerful as an independent of regulators, called the candle, was illustrated explosive agent than pure nitro-glycerin.

by those of Wilde and Jablochkoff. Mr. Preece also intro. That such is the case has been well established by duced to the audience a powerful lamp called the “holo. numerous experiments, but although this blasting gelatin phote," which is about to be introduced into the ports at may be detonated like dynamite by means of small

Spithead, with a view to testing their value in deteding quantities of confined detonating composition, when it is the advance of an enemy's torpedo. The many short. employed in strongly tamped blast-holes, or under con comings of the electric light-such as the noise, the ditions very favourable to the development of great initial flickering, the deep shadows-were referred to, as well as pressure, it behaves very differently from that material,

such advantages as the absence of smoke, and the purifi. or other solid though plastic preparations of nitro-glycerin,

cation instead of the poisoning of the air in large buildings, if the attempt is made to detonate it when freely | The electric light was pronounced to be at the present cxposed to the air or only partially confined. It not only 1 time in the tentative stage, there being, as Mr. Precce re. needs a much more considerable amount of strongly marked, three stages of every physical invention-the corfined detonating composition than dynamite and theoretic, when it is the dream of the philosopher; then similar preparations do, to bring about a detonation with the tentative stage, when it is the dream of the capitalist ; it under those conditions ; but when as much as 15 or 20 and the third stage, when the practical man realises these grains of confined fulminate are detonated in direct con

dreams. tact with it, although a sharp explosion occurs, little or The lecture was very warmly applauded. At its conclu. no destructive action results, and a considerable portion | sion the Duke of Edinburgh proposed, on behalf of the of the charge operated upon is dispersed in a finely-divided Council of the Royal Albert Hall, a vote of thanks to Mr. condition. This dispersion appears to take place to some Preece for his lecture. In the course of his speech His slight extent with dynamite also, when a small charge is Royal Highness said that the Council of the Royal Albert detonated in open' air, in consequence of its want of Hall was anxious to employ the electric light even in its rigidity, though the amount of explosive which thus present imperfect condition in lighting the building, and escapes detonation is very small as compared with the

would persevere until something satisfactory was accom. gelatin.

plished. The vote of thanks was seconded by His Royal (To be continued.)

Highness the Prince of Wales.

The Exhibition will remain open until Saturday, and

on Friday evening, at 8 o'clock, an explanatory lecture Temper of Steel.-M. Jarolımek maintains that steel will be given by Mr. J; N. shoolbred,

will be given by Mr. J. N. Shoolbred. The Council has can not only be hardened by immersion in boiling water, endeavoured to make the collection of apparatus embrace but even in boiling oil, melting lead, and melting zinc. the entire scope of all applications into which elextric Moniteur Scientifique.

| light striatly enters; and also as completely representa.

tive as possible of all the various methods hitherto own boiling point, the bulb is filled with the liquid, and devised for the production of the ele&ric light by suspended by a platinum wire in a glass vessel resembling mechanical means.

a large test-tube, having a bulb blown about half an inch from the bottom. A small quantity of the liquid is placed in this glass flask, and the bulb suspended by a platinum

wire from the cork which fits in the upper part of ihe flask. PROCEEDINGS OF SOCIETIES.

The liquid in the flask is caused to boil by a small Bunsen flame : the vapour heats the bulb, the liquid in it expands,

and drops are expelled from the capillary tube. As soon CHEMICAL SOCIETY.

as the drops cease to fall, usually in about ten minutes,

the bulb and its contents have assumed a temperature Thursday, May 1, 1879.

equal to the boiling point of the liquid. The bulb is with

drawn, allowed to cool, and weighed. Various precautions Dr. Warren De la Rue, President, in the Chair, must be taken with liquids which are very volatile or oxi.

disable. Allowance is carefully made for the expansion of The minutes of the previous meeting were read and con

the glass. The time required for one determination is firmed. The following certificate was read for the first

about half an hour. The author has made many detertime :-). Sakurai.

minations with a great variety of substances. His results, The PRESIDENT then called on Dr. W. Ramsay to read a

on the whole, agree very closely with those obtained by

Kopp. The value of some of the elements seems to vary paper “On the Volumes of Liquids at their Boiling-points

much. Thus, oxygen has two values, 3.49 and 5'45; sul. obtainable from Unit Volumes of their Gases." Kopp, in

phur 10'27 and 12.79. Nitrogen in amines is 2.3 ; in 1855, pointed out that the specific gravities of organic

cyanogen compounds, 17; in bodies containing NO2, 1714 compounds show a certain regularity with regard to each

(Kopp). The author has determined the ebullition volume other. If the molecular weights of various compounds be divided by their respective specific gravities at their value of N= 4:08: in its iscmeride aniline, N=2:11 ; in

of some of the pyridine series of bases, e.g., in picoline, boiling points, a series of numbers is obtained, which Kopp lpyrrol N=0:12. From its volume it appears to belong to ultimately named specific volumes. Kopp's method o the cyanogen group. In conclusion, the author draws determining the volume of a liquid at its boiling-point (the

attention to the enormous differences between these values only point at which volumes are comparable, for at that point the vapour-tensions of all liquids are equal) was to

of N, and suggests a connection between values and the

amounts of heat evolved in the formation of these sub. ascertain the boiling point with great accuracy, to deter

stances. mine the specific gravity of some known temperature, and

The next paper was read by Mr. J. PATTINSON, “ On a calculate the volume required by means of the coefficient

Method of Precipitating Manganese entirely as Dioxide, of expansion. This process involves the use of compli.

and its Application to the Volumetric Determination of cated and expensive apparatus, and necessitates laborious

Manganese." Many methods of determining manganese calculation. Before describing the apparatus used by him

volumetrically have been suggested, but none have come self, the author discusses the precise conceptions involved

into general use, owing principally to the difficulty of obin the expressions used by Kopp, &c.-"Atomic volume,"

taining the whole of the manganese in a definite and uni. “ molecular volume," and "specific volume :" specific

form state of oxidation. The auihor has examined the volume as used by Kopp =

methods suggested by Pereno and Lenssen, but did not molecular weight

succeed in obtaining regular results. Wright and Luff specific gravity

have also been unable to obtain pure manganese dioxide By molecular weight is meant the specific gravity of the

by any of the ordinary methods. After nunerous experi. gas, hydrogen at oo being equal to 1; specific gravity

ments the author found that the whole of the manganese water = 1; so that two scales are employed, viz., one

in a solution of manganous chloride could invariably be based on H, as unity, and one based on water. The

precipitated in the condition of dioxide, is a certain amount number obtained from tbe above equation, therefore, does

of ferric chloride be present, by a sufficient excess of a not give the relation between the volumes and weights of solution of calcium hypochlorite or bromine water, adding, liquids at their boiling points and that of the gases obtain. 1

after heating the solution to from 140° to 160° F., an excess able from those liquids. To obtain this relation, the num.

of calcium carbonate, and then well stirring the mixture. ber representing the specific gravity of the liquid must be

Without the ferric salt the precipitation as MnO2 is im. multiplied by the number which represents the relation

perfect. Zinc chloride may be substituted for serric chloride, between the specific gravity of water and that of hydrogen,

but neither aluminium nor barium chlorides have the same i..., 22,326. By reversing Kopp's process, i.e., by dividing

desirable effect. The author recommends the following the sp. gr. of the boiling liquid by that of the gas, the

solutions, &c. :-The clear liquid obtained by decantation amount of gas ubtainable from unit volume of the liquid

from a 1'5 per cent solution of bleaching-powder; light is calculated. Thus, specific volume of liquid hydrogen

granular calcium carbonate obtained by precipitating an

excess of calcium chloride by sodium carbonate at 180° F.; =5'5, and its sp. gr. is -- or oʻ1818, and o•1818 x 22326 a i per cent solution of ferrous sulphate in dilute (1 in 4)

su!phuric acid ; standard solution of potassium dichromate = 4059*2, the sp. gr. of liquid hydrogen (hydrogen gas

equivalent to i part of iron in 100 of solution. The appli=I). By dividing the sp. gr. of gaseous hydrogen by that cation of the process to manganiferous iron ores is as fol. of liquid hydrogen, or we get o'00024635 as the

lows:-10 grains of the ore, dried at 212°, are dissolyed in

a 20-oz. beaker in about 100 fluid grains of hydrochloric volume of liquid obtainable from I volume of gas, or 2:46 acid (sp. gr., I'IS). Calcium carbonate is then added until from 10,000 vols. of gas. This number (2:46) the author free acid is neutralised and the liquid turns slightly red. proposes to call “ebullition volume.” Kopp's numbers dish. 6 or 7 drops of HCI are ncw added, and 1000 grains give the amounts of boiling liquids obtainable from 22,326 / of the bleaching powder solution, or 5co grains of satu. vols. of gas at oo. The apparatus used by the author con- / rated bromine-water, and boiling water run in until the sists of a thin glass bulb of about 10 c.c. capacity, in shape temperature is raised to 140° to 160° F.; 25 grains of callike a lemon : its upper end is terminated by a hooked cium carbonate are added, and the whole well stirred. If capillary tube, and its lower end is closed, and furnished the supernatant solution has a pink colour, the permanwith a glass hook. The capacity is accurately determined ganate is reduced by a few drops of alcohol. The preci. by filling with boiled distilled water and weighing. To pitated oxides of iron and manganese are filtered off and determine the weight of a known yolume of a liquid at its ! washed. 1000 grains of the acidified ferrous sulphate

595

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