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272 Chemical Notices from Foreign Sources. { CABOCCAL, 18.

Dec. 22, 1876. tabular form except with certain groups, such as the alcohols CHEMICAL NOTICES FROM FOREIGN and the cyanogen compounds. In general, however, space does not allow him to do more than define such classes as

SOURCES. the ketones, amines, phosphines, &c.

The last portion of the work is a synopsis of poisons Nore.-All degrees of temperature are Centigrade, unless otherwise with their antidotes and general treatment.

expressed. The work upon the whole may be pronounced useful, and we hope that a future edition may see it freed from the oversights which we have pointed out, from certain Comptes Rendus Hebdomadaires des Seances, de l'Acadenis typographical errors, and from the repetition of matter in

des Sciences. No. 21, November 20, 1876. different places.

Physical and Chemical Properties of Ruthenium.
-MM. H. Sainte-Claire Deville and H. Debray.-(See

page 265.) Notes on Certain Explosive Agents. By Walter N. Hill, S.B., Chemist at the U.S. Torpedo Station. Produced by Electricity of Tension.-M. Berthelot.

New Researches on the Chemical Phenomena Boston: J. Allyn.

-In this paper the author examines what relations may This work treats first of explosions and explosive exist between the chemical actions of electricity and the bodies in general; then of nitro-glycerin and its com sign or tension of the electricity. He finds that ozone is mercial mixtures; and of gun-cotton, which, with Prof. formed equally under the influence of positive and of Abel, the author regards as trinitro-cellulose, and which negative electricity. It is formed abundantly only unde: he distinguishes from the lower substitution products used the influence of strong discharges. In operating upon for making collodion. Like most chemists he admits the mixtures of nitrogen and oxygen (both moist and dry) impossibility of sulphuric acid remaining in gun-cotton with the Holtz machine not the least trace of nitrous after it has undergone the process of washing, directed compounds has been observed, although a quantity under Abel's patent, and concurs in the conclusion smaller than 1-50th m.grm. could have been detected. arrived at in England that the Stowmarket explosion | Traces have been produced with the "effluve" of a Ruhmmust have been caused by the intentional addition of korff apparatus. Acetylen is formed in notable amount sulphuric acid to the finished product.

in the vapours of organic compounds sealed up with The picrates and fulminates used as explosives are next nitrogen in tubes containing a metallic armature, and described. In considering the respective forces of the acted on by the discharges of the Holtz machine. The agents in question ne pronounces nitro-glycerin eight absorption of nitrogen by organic compounds is effected times as powerful as gun-powder, dynamite six times, and equally under the influence of both electricities. gun-cotton from four to six times. He draws, however,

Composition of Certain Phosphites.-A. Wurtz.a very imporant distinction. “ The harder and firmer the The phosphites in question are those of calcium and of material to be blasted the more effective, proportionally barium (acid and neutral). nitro-glycerin or gun-cotton will be. In sost materials the reverse is true.”

Modifications of Elæomargaric Acid Produced by As regards comparative safety he considers both nitro. Light and Heat.-—M. S. Cloëz.—These observations glycerin and gun-cotton to have the advantage over gun

on the modifications of elæomargaric acid explain in the powder.

most satisfactory manner the curious properties of the oil of Eleococca. This oil contains 75 per cent of elæomargarin,

the remainder being ordinary olein. On saponification Disease of the Sugar Cane, Queensland. By Professor the elæomargaric acid yields solid eläomargaric acid and LiversiDOE. Sydney : Gibbs, Shallard, and Co.

glycerin, whilst the olein furnishes oleic acid and gly.

cerin. In the oil congealed under the influence of light, Epidemic disease among important crops seems to be on the liquid elæomargarin is changed into solid elæostearin, the increase. The potato and the vine have long been accompanied with a small quantity of liquid elæolin; the sufferers, and, according to a writer in the Comptes ordinary olein undergoes no change. Saponification yields Rendus the latter is now attacked by a new malady, quite elæostearic, elæolic, and oleic acids. Oil heated for a distinct from the effects of the phylloxera. The coffee long time to 180° with the exclusion of air loses the power plantations of Ceylon are said to be withering away from of becoming solidified under the action of light. This is some unexplained cause, and now the sugar cane in because the elæomargarin is completely transformed into Queensland is affected with a disease, which is locally I eläolin. known as "rust.” Prof. Liversidge, of the University of Sydney, who has made an official examination of the -M. F. Jean.-The quantitative determination of sul,

Note on a Method of Titrating Alkaline Sulphates. diseased canes and the soils in which they grow, does not consider that the malady springs from some one specific phuric acid combined

with potassa and soda may be effected cause, but is due to imperfect cultivation, of which he very rapidly and exactly by means of a simple alkalimetric certainly points out some decided prooss.

titration. The aqueous solution of the substance in which the sulphuric acid combined with the fixed alkalies is

mixed with a slight excess of baryta water, and then with Proceedings of the Madras Government, Public Works Seltz water. The excess of baryta is precipitated in the Department. February 21st and December 10th, 1874. state of baric carbonate, but as the carbonic acid would

be able to dissolve this salt the liquid is decanted from A report from Surgeon E. Nicholson on the qualities of the precipitate, which settles rapidly; it is raised to a boil limestones and cements.

and the whole is filtered. On account of the carbonate which envelopes the sulphate and acts like starch the

filtration is effected very easily. The mixed precipitate Sanitary Effects of Eucalyptus Globulus.-Between having been washed with boiling-water until the washing Nice and Monaco there is a locality so unhealthy that the waters no longer present an alkaline reaction, the filtrate Paris, Lyons, and Mediterranean Railway Company have is mixed with tinature of litmus, raised to a boil, and been obliged to change every two or three months the titrated with a standard solution of sulphuric acid. The watchman at a crossing there. Plantations of the quantity of sulphuric acid necessary to saturate the Eucalyptus have been formed there, and at present the alkalies set at liberty by the baryta water is exactly the same watchman has resided there for several months with same as what was combined with the alkalies, potassa and his family without experiencing the least inconvenience. soda, in the original matter. The titration of the alkaline --Les Mondes.

sulphates may be effected by his process as rapidly as

CHEMICAL NEWS,} Chemical Notices from Foreign Sources.

273

ESTABLISHED 1798. the alkalimetry of a sample of carbonate of soda. On operating with dilute solutions, and under the conditions indicated above, the alkaline carbonates do not decom. ROBERT DAGLISH & Co., pose the sulphates of baryta. This process may be ad. vantageously applied to the titration of the salts of BOILER MAKERS, ENGINEERS, AND Stassfurt and of Bene, so much employed in agriculture.

MILL-WRIGHTS, These salts, besides the alkaline sulphates, contain sul.

BRASS AND IRONFOUNDERS, phates of lime, magnesia, &c., which render the determination of the alkaline sulphates by ordinary methods very ST. HELEN'S FOUNDRY, LANCASHIRE. tedious, and necessitate a complete analysis of these salts. By the method of titration which I point out these Makers of every description of Chemical, Colliery, Copper Ore, Gold sulphates of lime, magnesia, &c., do not interfere, since Mining and Glass Machinery, including Crown, German Sheci, and these bases are precipitated by carbonic acid, whilst only | Ireland, Scotland, and Wales.

Plate Glass Plant, as supplied to some of the largest Firms in Engiand, the sulphates of potassa and soda enter into solution. Makers of the latest Improved Revolving Black Ash Furnace This process is equally suitable for the assay of alkaline with Siemens's Patent Gas Arrangement, and as used in the Manufac

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APPARATUS, of pure ammonia in a test-tube. He adds to the mixture 5 to to c.c. of chloroform and agitates again, closing the Suitable for Manufacturers, Professors, and end of the tube with the thumb and inverting several times, and finally pours the whole into a glass funnel Iron Retorts, Stands, Receivers, Stills, Condensers, Purifiers, Pepys

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A. CAPLATZI, placed on the sand-bath. A small piece of white silk is

AT THE SCIENCE DEPÔT AND EXCHANGE, then steeped in the liquid and heat is applied. As the CHENIES STREET, TOTTENHAM COURT ROAD. chloroform escapes, the magenta, if present, is fixed on the CORRIS TANNENBAUM, 37, FITZROY silk and dyes it a rose colour. Pure wine does not dye

STREET, offers Jewellers, Mineralogists, Lapidaries, and silk a rose colour. To prove that the colouration is due specially Collectors of Rare Cut Gems (which he possesses in all to magenta it is sufficient to put the swatch of silk into a existing kinds), large Collections of Fine Hyacinths in all Colours, little ammonia, when the rose colour at once disappears Olivine, Fossils

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Matrix, Fine Crystallised Rubies and Brazilian Topazes, and of Magenta (in Wines).—MM. P. Guyot and R. Bidaux.

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274

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Dec. 29, 18,} Experimental Contributions to the Theory of the Radiometer.

275

the mercury pump I have been able to measure the atmo. THE CHEMICAL NEWS. spheric pressure at any desired stage of exhaustion.

I have not only measured the force of repulsion, but also

the viscosity of the residual gas, and from the results VOL. XXXIV. No. 892.

plotted I have the observations in curves which accompany this paper, and which show how the viscosity of the residual gas is related to the force of repulsion exerted by

radiation. These curves must not, however, be considered EXPERIMENTAL CONTRIBUTIONS TO THE as representing more than the broad facts, for I have not

included in them my final observations, which in all pro. THEORY OF THE RADIOMETER.*

bability will introduce modifications in them. PRELIMINARY NOTICE.

In plotting these curves I have supposed my scale to te By WILLIAM CROOKES, F.R.S., &c.

1000 metres long, and to represent one atmosphere. Half

way up the scale therefore, or 500 metres, represents half INSTEAD of bringing another preliminary notice before the an atmosphere ; 999 metres up the scale represents an Society, I should have preferred reserving the announce exhaustion of I-1000th of an atmosphere; each millimetre, ment of my new results on the Repulsion resulting from therefore, stands for the millionth of an atmosphere. Radiation until they were fit to be offered in a more com

My results have principally been obtained at the top of plete form ; but the radiometer

is now so much occu- the scale, and it is the last quarter of a metre which suppying the attention of scientific men, and results of plies the diagrams accompanying this paper. experiments with this and allied instruments are appearing When the residual gas is air, the viscosity (measured by so frequently in the scientific journals at home and the logarithmic decrement of the arc of oscillation) is abroad, that were I not to adopt this method of bringing practically constant up to an exhaustion of 250 millionths the results of my more recent experiments before men of of an atmosphere, or oʻ19 millim. of mercury, having only science, I might find myself anticipated in some or all of diminished is om o 126 at the normal pressure of the atmothe conclusions at which I have arrived.

sphere, to o 112. It now begins to fall off: at 200 millionths

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ratus.

On June 15th last I mentioned to the Society that the it is oʻ110 ; at 100 millionths it is ooo96; at 50 millionths repulsion resulting from radiation increases up to a cer- it is 0.078; at 20 millionths it is o‘052; at 10 millionths tain point as I exhaust the air from the torsion appa- ! it is o'035; and at o'l of a millionth of an atmosphere, the

After long.continued exhaustion the force of log.dec. has fallen to about oor. Simultaneously with this radiation approaches a maximum, and then begins to fall decrease in the viscosity, the fire of repulsion exerted off. I have since succeeded in experimenting at still on a black surface by a standard light varies. It increases higher exhaustions, and with different gases in the appa: very slowly till the exhaustion has risen to about 70 mil. ratus; and by means of a McLeod gauge attached to lionths of an atmosphere ; at about 40 millionths the force

is at its maximum ; and it then sinks very rapidly, till at

0:1 millionth of an atmosphere it is less than one-tenth of * A Paper read before the Royal Society, November 16, 1876.

276 Experimental Contributions to the Theory of the Radiomeier. (CHEMICAL News, its maximum. On continuing the curves of the log. rises, the repulsive force of the candle increases to its maxdec. and the force of radiation, and assuming that the imum, and then slowly diminishes to zero, the log. dec. contorsion fibre of glass has no viscosity, it is most probable tinuing to rise till it shows that the internal and external that they both would come to zero when the last traces of pressure are identical. With a fine perforation several an atmosphere had been taken out of the apparatus. days are occupied in going through these phases, and they

The oxygen diagram differs from that of air. The take place with such slowness and regularity as to afford log. dec. is o‘126 at the atmospheric pressure ; it falls to opportunities for getting valuable observations. o'111 at a pressure of 250 millionths of an atmosphere ; The improvements now added by Mr. Gimingham to at 100 millionths it is o 105 ; at 50 millionths it is o'093 ; the pump render it so easy to obtain high exhaustions at 20 millionths it is o'o68; and at 2 millionths it is o'02. that, in preparing experimental radiometers, 1 prefer to The force of repulsion in oxygen increases very steadily exhaust direct to one or two millionths of an atmosphere. up to an exhaustion of about 40 millionths of an atmo- By keeping the apparatus during this exhaustion in a hot sphere; it is at its maximum at about 30 millionths, and air-bath heated to about 300° C. for some hours, the thence declines very rapidly.

occluded gases are driven off from the interior surface of Hydrogen gives a remarkable diagram. The viscosity the glass and the fly of the radiometer. The whole is then at the normal pressure is measured by a log. dec. of o‘063; allowed to cool, and attenuated air from the air trap is put at 250 millionths of an atmosphere it is 0.057 ; at 100 in in small quantities at a time, until the McLeod gauge millionths it is o'052 ; at 50 millionths it is o`046, whence shows that the best exhaustion for sensitiveness is it rapidly sinks. The force of repulsion increases slowly reached ; if necessary this point is also ascertained by up to an exhaustion of 250 millionths, then quickly until testing with a candle. Working in this way I can now it' attains its maximum at about 50 millionths, and it the do in a few hours what formerly required as many rapidly sinks. The force of repulsion is very great in a days: In this manner, employing hydrogen instead of hydrogen vacuum, being in comparison with the maximum air for the gaseous residue, and using roasted mica in an air vacuum as 70 to 41. Neither is it necessary to vanes set at an angle with the axis, as described further get so high an exhaustion with hydrogen as with other on, I can get very considerably increased sensitiveness in gases to obtain considerable repulsion. This shows that radiometers. I am still unable, however, to get them to in the construction of radiometers it is advantageous to move in moonlight. The statements made by an observer fill them with hydrogen before exhausting.

nearly a year ago, that he obtained strong rotation by Carbonic acid has a viscosity of about o'or at the normal moonlight, must therefore be considered as erroneous. pressure, being between air and hydrogen, but nearer the My, most sensitive torsion balance will, however, move former. On approaching a vacuum the force of repulsion easily to moonlight. does not rise very high, and soon falls off.

The above-mentioned facts, in addition to what has Before working with this apparatus I thought that mono- already been published, leave no reasonable doubt that hydrated sulphuric acid evoived no vapour, and I there. the presence of residual gas* is the cause of the movefore freely used it for cleaning out the pump and for ment of the radiometer. But few theories are sufficiently drying the gases. I can even now detect novapour tension, strong not to require reinforcement, and in the present case but a comparison of the curves, with and without sulphuric very much remains to be ascertained as regar's the mode acid, shows that the presence of this body modifies the of action of the residual gas. The explanation, as given results. One of my curves represents the action of the resi- by Mr. Johnstone Stoney, appears to me the most dual sulphuric anhydride gas. The experience thus gained probable, and having stood almost every experimental test has led me to adopt phosphoric anhydride for drying the to which I have submitted it, I may assuine for the present gases. I can detect no ill effects from the presence of this that it expresses the truth. According to this the repul. agent, and I have been able in consequence to push the sion is due to the internal movements of the molecules of rarefaction to higher points than before.

the residual gas. When the mean length of path between The McLeod gauge will not show the presence of mer- successive collisions of the molecules is small compared cury vapour. It is therefore possible that I have a greater with the dimensions of the vessel, the molecules, reboundpressure in the apparatus than is here stated. have, ing from the heated surface, and therefore moving with an however, entirely failed to detect the presence of mercury extra velocity, help to keep back the more slowly moving vapour at any great distance from the mercury in the molecules which are advancing towards the heated pump; and the tube packed with gold-leaf, which I fre- surface; it thus happens that though the individual kicks quently interpose between the pump and the apparatus, against the heated surface are increased in strength in shows no trace of bleaching, and exerts no appreciable consequence of the heating, yet the number of molecules effect one way or the other on the results.

struck is diminished in the same proportion, so that there With this pump, assisted sometimes by chemical ab. is equilibrium on the two sides of the disk, even though sorption, it is not difficult to exhaust a radiometer to such the temperatures of the faces are unequal. But when the a point that it will not move to a candle placed a few exhaustion is carried to so high a point that the molecules inches off; but I have not yet succeeded in stopping the are sufficiently few, and the mean length of path between movement of the beam in the torsion apparatus.

their successive collisions is comparable with the dimen. A long series of observations have been taken, at dif- sions of the vessel, the swiftly moving, rebounding moleferent degrees of exhaustion, on the conductivity of the cules spend their force, in part or in whole, on the sides residual gas, to the spork from an induction coil. Working of the vessel ; and the onward crowding, more slowly with air, I find that at a pressure of about 40 millionths of moving molecules are not kept back as before, so that the an atmosphere, when the repulsive force is near its max. number which strike the warmer face approaches to, and imum, a spark, whose striking distance at the normal in the limit equals, the number which strike the back, pressure is half an inch, will illuminate a tube having cooler face; and as the individual impacts are stronger on aluminium terminals 3 millimetres apart. When I the warmer than on the cooler face, pressure is produced, push the exhaustion further, the 4-inch spark ceases causing the warmer face to retreat. to pass ; but a 1 inch spark will still illuminate the I have tried many experiments with the view of putting tube. As I get nearer to a vacuum more power is this theory to a decisive test. The repulsive force being required to drive the spark through the tube, but at due to a reaction between the fly and the glass case of a the highest exhaustions I can still get indications of

* It is a question whether the residual gas in the apparatus, when so conductivity when an induction coil, actuated with five highly attenuated as to have lost the greater part of its viscosity, and Grove's cells, and capable of giving a 6-inch spark, is used. to be capable of acquiring molecular movement palpable enough to When so powerful a spark is employed there is great

overcome the inertia of a plate of metal, should not be considered to

have got beyond the gaseous state, and to have assumed a fourth danger of perforating the glass, thus causing a very slight state of matter, in which its properties are as far removed from those leakage of air into the apparatus. The log. dec. now slowly of a gas as this is from a liquid.

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