« PoprzedniaDalej »
THE CHEMICAL NEWS.
inflamed by the heat developed where the fulminate is detonated, a result which is obtained with greater certainty the less violent the detonation produced by the fulminate
charge. If, however, the gun-cotton be converted into a VOL. XXXIX. No. 1014.
compact form, either by ramming the wool or thread very tightly into a case, or better still, by reducing the gun. cotton fibre to a very fine state of division, and compressing
it, when in that condition, into compact masses, it becomes RECENT CONTRIBUTIONS TO THE HISTORY
susceptible of detonation by the initiative action of merOF DETONATING AGENTS.
curic fulminate, and the quantity of the latter required to
bring about detonation is small (down to the limit which By Professor ABEL, C.B. F.R.S.
has been named above) in proportion as the compactness (Continued from p. 179.)
or density of the compressed material is increased.
Detonation, when established in compressed gun-cotton, The physical character of explosive substances, as also
is transmitted with great velocity throughout the mass, as the mechanical condition of a mass of the particular ex.
already stated, or from one to another of contiguous plosive substance operated on, are of great influence in
masses, laid out in long rows, and even, though at a determining its behaviour when submitted to the action
reduced rate, if small spaces exist between the individual of an initiative detonation. The liquid nitro.glycerin is
masses. But, if a small mass of compressed gun-cotton far more sensitive to detonation than gun-cotton.; one
freely exposed to air be detonated when in immediate congrain of mercuric fulminate, confined in a metal case,
tact with gun-cotton wool or loosely twisted yarn, the suffices to detonate nitro-glycerin when surrounded by it:
detonation will not be transmitted to these, but they will but, in order to attain this result with any degree of cer.
merely be scattered and perhaps infiamed. tainty, it is necessary so to confine the nitro-glycerin as to
The difference in the behaviour of nitro-glycerin and of prevent its yielding to the blow developed by the initiative
gun-cotton when presented to the action of a so-called detonation, and thus to some extent escaping from the
initiative detonation under the different conditions spoken operation of the sudden concussion to which the particles
of above, admits of ready explanation. contiguous to the fulminate charge are submitted.
It was established, in the first instance, that the action If nitro-glycerin be mixed with solid substances in a fine
of an initiative detonation is not ascribable to the heat state of division plastic mixtures may be obtained, and the
developed within the detonating material itself in under. liquid may thus be presented in something like a solid I going chemical metamorphosis. If it were so, the detoform to the detonating agent. If the particles of absorbent
nating mixture known as percussion-cap composition and material be, moreover, of porous nature, as is the case
other explosive mixtures, the detonation of which is with the infusorial earth called Kieselguhr, used in the
attended by much greater development of heat than is production of dynamite, a solid nitro-glycerin preparation
obtained by the action of pure mercuric fulminate, should may be obtained which contains a very large proportion
detonate gun-cotton more readily than the latter does, of the liquid (75 per cent by weight). In this condition
whereas very much larger quantities of such materials are nitro-glycerin may be detonated without any difficulty
required to attain that result. Moreover, the readiness when freely exposed to air; and although it is diluted with
with which gun-cotton is detonated should be solely pro. a considerable proportion of absolutely inert material, its
portionate to the amount of fulminate used, which has sensitiveness to detonation is not in the least diminished. I
been shown not to be the case; and gun-cotton should be Each particle of the diluent is enveloped in the liquid, so
more readily detonated when in the loose and open con. that no portion of the latter becomes isolated from the
dition than in the highly compressed or compact form, remainder by the admixture of inert solid matter; hence,
because the latter presents it in the condition least favour. when the initiative detonator is surrounded by such a mass
able, and the former in that most favourable, to ready and it is in contact at all points with some portion of the nitro.
rapid transformation by heat. Again, the actual tempera. glycerin, and the latter is in continuous connection through-|
ture required for the explosion of nitro-glycerin is very out, though no longer in a mobile condition; detonation |
¡ considerably above the exploding temperature of gun. is consequently as readily established and transmitted
cutton, yet a very much smaller charge is required for the through the mass as though it consisted entirely of nitro.
detonation of nitro-glycerin than is needed for the detona. glycerin. Indeed, while the liquid in its undiluted state,
tion of gun-cotton. On the other hand, a quantity of if freely exposed to air in a long layer, transmits detonation
confined percussion-cap composition which, if it were pure with difficulty and very slowly as compared with com
mercuric fulminate, would be altogether inadequate for pressed gun.cotton (the observed rate of progression being,
the detonation of gun-cotton, suffices for the detonation in several experiments, below 6000 feet per second), deto
of nitro-glycerin. nation is transmitted with ease and certainty through very
The action of an initiative detonation has already been long trains of a solid preparation of nitro-glycerin, such
compared to that of a blow from a hammer or falling as dynamite, and the rate of transmission is decidedly
weight. The readiness and certainty with which gunmore rapid than it is with compressed gut-coiton, a result
powder, gun.cotton, and other explosive agents are deto. which is in harmony with the greater sensitiveness to de
nated by the latter agency are regulated by several circum. tonation and the greater violence of action of nitro
stances; they are in direct proportion to the weight of the glycerin.
falling body, to the height of its fall, and to the force with It has already been stated that gun-cotton may be
which it is impelled downwards; to the velocity of its detonated if a confined charge of not less than 2 grains of
motion; to the mass and rigidity or hardness of the support inercuric fulminate be detonated when closely surrounded upon
Grounded | upon which the substance tu be detonated rests; lastly, co by the substance. But in order to attain this result, the
the quantity and mechanical condition of the explosive cellulose product must be presented to the detonating
agent struck, and to its sensitiveness. agent in a mechanical condition favourable to its action.
Gunpowder is much more readily detonated by a sharp Gun-cotton in a loose flocculent condition, or even if in
| blow from a small hammer than by the simple fall of a the more compact form of a spun yarn or thread, cannot
I heavy hammer, or by a comparatively weak blow from the be detonated through the agency of a large fulminate
| latter. It is very difficult by repeated blows, applied at buried in the material. The light and loose gun-cotton is
very brief intervals, to detonate gun-cotton is placed upon simply scattered with violence ; portions are sometimes
a support of wood or lead, both of which materials yield
to a blow, the force applied by that blow being transferred * Abstraat of a Paper read before the Royal Institution of Great
through the explosive agent and absorbed in work done Britain, Friday, March 21, 1879.
upon the material composing the support. But if the latter
Erd-on Illumination in Private Spectroscopy.
(CRRMICAL Note: 1 May 2, 18793
be of iron, which does not yield permanently to the blow | END-ON ILLUMINATION IN PRIVATE of the bammer, the detonation of those substances is easily
SPECTROSCOPY, accomplished. If the quantity of the explosive agent em
AND ITS ployed be so considerable as to form a thick layer between the hammer and support, the force applied is to so great | APPLICATIONS TO BOTH BLOWPIPE FLAMES an extent expended in imparting motion to the particles of
AND ELECTRIC ILLUMINED the compressible mass, that there remains little or none by
GAS-VACUUM TUBES.* which its detonation can be accomplished, and if the
By PIAZZI SMYTH, material be in a loose or porous condition (as in the case Astronomer Royal for Scotland, and Past President of R.S.S. Arts. of a powder or a loose wool), much work has to be accomplished in moving particles of the mass through a com
(Continued from p. 163). paratively considerable space, in the operation of compressing them, so that a second or even a third blow is
PART III. required for their detonation ; whereas if, by blows or
Electric-Spark Spectroscopy in Vacuum Tubes. pressure previously applied, the explosive material will be presented in the form of a compact mass, the particles of
The next step in spectroscopy, after flame lines, can which have little tendency to motion when force is applied
hardly be anything else than the simple induction spark oí to them, detonation will be much more readily developed. It
electricity in rarefied gas tubes. For the most infinitely appears, therefore, that the detonation of an explosive
small weight of the particles to be moved or heated there, substance by means of a blow is the result of the develop
allows a very trifling quantity of electricity, and in uncon. ment of heat sufficient to bring about most energetic
densed form, to produce abundantly visible effects. These chemical action, or change, by expenditure of force in the
effects, moreover, supplement in a remarkable manner compression of the material, or by establishing violent
our knowledge of gases as given by flame experiments. friation between its particles, consequent upon the motion | Thus on burning pure hydrogen flamewise in the open momentarily imparted to them, and that it is brought
air, no spectral effects of lines or bands are seen ; because, about with readiness proportionate to the resistance which as it is said, the very act of burning being a combination they oppose to their motion by the degree of their con
of that hydrogen with the oxygen of the air, water is tiguity to each other.
formed, and hydrogen ceases to exist as an independent en. The exceedingly violent motion of particles resulting
tity. Butin a close glass tube filled with hydrogen, the elecfrom the sudden or extremely rapid transformation of a
tric spark passing through it, heats that gas by itself solid or liquid explosive body into highly heated gas
alone ; and then, not only do we see the hydrogen's or vapour (which is the effect of a detonation), must
spectral lines, but recognise them immediately as some obviously exert force which operates upon a body opposed
of the most extensively distributed and most important to it in a manner precisely similar to the force applied by
throughout all the universe. For when the populace is opposing a body in the path of a solid mass which is set
in ecstasies at a total solar eclipse, on seeing the red. into very rapid motion. In other words, a detonation
prominences outside the sun's circumference, and wonders exerts a mechanical effect upon resisting bodies precisely
what they are,—the spectroscope pronounces them to be similar to that of a blow from a hammer or from a pro
“ flames of incandescent hydrogen of most enormous jectile propelled from a gun. Just as the force of a suf.
size." ficiently sudden or powerful blow from a hammer is
Again, when the astronomer finds occasionally what is transformed into heat by the resistance to the motion of called a new star, or rather an old one which has suddenly the hammer which the particles of an opposing body offer,
become 500 times brighter than before, and must be a and by the consequent friction established between them,
sun on fire,--a sun destroying all the life on the planets so the force or concussive action exerted by the matter
immediately around it,-it is an immense extravasation of set in motion when a solid or liquid is converted into gas
incandescent hydrogen which has done the business. or vapour, will also be transformed into heat, the develop.
And then we are induced to speculate on whether the ment of which in an opposing body will be proportionate to
similar in kind, though happily smaller in quantity, the resistance to motion which its particles offer, and to
extravasations, which make the red-prominence round the suddenness and violence of the concussion to which
our own sun sometimes large and sometimes small, are, it is subjected. The power of accomplishing the deto. or may be, regulated by cyclical law; and what length of nation of nitro-glycerine, gun-cotton, or other highly ex time, if any, may probably separate us from the next of plosive substances, freely exposed to the air, through the
their greater effluxes ? agency of detonation produced in their vicinity or in close
These spectral lines of incandescent hydrogen (four in contact with them, appears therefore corectly ascribable
number, red, glaucous, violet, and a very faint one in the to the heat suddenly developed in some portion of the mass
lavender) are therefore rather eerie things to look at; by the mechanical effect, or blow exerted by that detona.
should never be forgotten by man; and may, in the tion, and is regulated by the violence and suddenness meanwhile, be turned into, and have been already exten. (either singly or combined) of the detonation, by the ex
sively used as, most useful companions at the spe&trostent to which the particles composing the mass of the
cope, through means of the following five inventions, explosive material are in a condition to oppose resistance
none of them very old. to the force, and by the degree of sensitiveness of the sub
Ist. Prof. Geissler of Bonn introduced the exceeding stance to detonation, or to sudden metamorphosis, under
rarefaction of gases within hermetically sealed glass tubes, the influence of heat thus developed.
armed at each end with platinum wire electrodes.
2nd. Prof. Plucker, also of Bonn, brightened up the (To be continued.)
light of those tubes by reducing the diameter of the bore of the central part until it was no more than capillary.
3rd. M. Ruhmkorff of Paris improved and vastly rein. Eupitton and Pittakall.-A. Grätzell.-The author forced the induction coil. points out a number of characteristics which distinguish 4th. Dr. Leeson planned the bichromate galvanic eupitton from pittakall. The latter gives a blue precipi. battery, with its notable power, and absence of poisonous tate with alkalies even in an acid solution, whilst eupitton fumes; and forms a brown precipitate. Pittakall is precipitated from 5th. Soine artist in arrangement produced the longits acetic solution by acid acetate of alumina, whilst necked bottle-form of that battery, enabling its power to eupitton is not. It does not seem probable that Reichen. | be called forth at intervals of either minutes, or months, bach was acquainted with eupitton.-Berichte der Deutsch. or years, without any intermediate preparation or attention. Chem. Gesell..
For mere reference to the first three, and brightest
hydrogen lines, a one-pint bichromate bottle, with a zinc | to air in any way, were caused by carbonaceous impuri. plate 3.0 by 1'5 inches, a small coil giving a f-inch spark, ties. In fact I had stumbled, and at the very right time for it and a transverse view are enough, and even more than on one of the grandest cases of dispute in modern specenough. But for original investigations into the more troscopy, viz., "Is it carbon vapour, or carbon-compound untoward of the gases for lighting up, far more power vapour ? carbon by itsell, or carbo-hydrogen?” So I im. and illumination are necessary. To a certain extent, any mediately increased the prism power 33° between A and wealthy observer can obtain that higher degree of illumina. | H; and then, looking at the minute spectral space, which tion most easily, hy merely increasing the size of his formed the crucial instance to be measured, -where, batteries and coils with the consequent length of their just in front of the “green giant," the best leading autho. sparks. But then their at-the-same-time growing heat rity in the “ Philosophical Transactions of the Royal will crack and destroy the tubes so rapidly, that even the Society," London, has only eight lines, and those dark richest man may be at last driven to inquire, whether the ones, -I there saw most clearly, and measured, 31 lines, end-on principle just brought forward, with the claim of and all of them bright ones. increasing brightness without altering the temperature at After such an example as that, I need not probably say all, be not applicable ?
anything more in furtherance of the principle of the end. It is a case for it undoubtedly; for the line of light in a on-view kind of gas vacuum tubes. But I would beg Geissler-Plucker tube is still longer in proportion to its leave to call the attention of so practical a meeting as the breadth than any blowpipe flame, and usually wastes its present, to the facility of manipulating the end-on tubes precious light in the proportion of 99 to 1. But as these ( by means of the peculiar holder for them when under the tubes are now made they cannot be employed end.on. electric spark; also to the anti-heating character of the Their poles come in the way, two lions at once, totally large, thin copper plates adopted as terininals for the inobscure the view. A very considerable alteration of duction wires, in place of the small brass wire spirals, arrangement is therefore necessary; and not every manu. usually employed; and to the packing-boxes lined with facturer will take the trouble of experimenting for a single cork and armed with thick grooved cork; all of which private observer. I wrote therefore to my trusty old have been made for me, and greatly to my satisfaction by, friend M. Salleron in Paris; and he, with the enthusiasm of Mr. John air, of the firm of Air and Candow, cabineta scientist, joined to the practical capacities of a maker of makers, Leith Walk. instruments of precision, promptly realised for me one But the vacuum tubes themselves, including, besides design after another of the end-on gas vacuum tubes, the “air-pure," examples of until we at length reached a very promising standard both of size and shape, as thus:
Carbonic Dioxide The new tubes are shorter, broader, stronger than the
Alcohol old ones; more easy manipulated, and safely packed and Hydrogen
Marsh Gas carried; while, finally, in place of a uselessly long line Nitrous Oxide
Olefiant Gas, and of faint light, they give a small point of brilliant light.
Ammonia And they are likely to show this for a longer time; as, instead of that point of light (really the axis of the long
have all been prepared, as already intimated by M. Jules capillary seen end-on) being looked at through the thick
Salleron, 24 Rue Pavée au Marais, Paris; and so success. glass walls of the said capillary, which frequently get
| fully that I do hope he may be encouraged by the patronage dimmed inside by oxidising and carbonising effect of the
of many spectroscopists to apply his rare abilities more electric heat, they are viewed through the thin walls of
extensively to the preparation of similar gas-vacuum tubes the bulbs, whose very large diameter keeps down the heat
for all known chemical volatile products. Indeed I do on themselves and prevents those darkening effects. At
know that he is ready, according to the prospects which the same time all the rest of the glass, except one peep
may open up, to have specially infusible glass prepared, t hole, being silvered externally (and then black.varnished
and to organise a system of engraving all the chief data for protection), there is some furiher ircrease of brightness
of each tube, as it is made, on the outside of the bulbs, in by internal reflection.
a manner which must increase confidence of the scientist I show now a box of these tubes whose light, under a
who uses them afterwards, exceedingly. standard spark of 1 inch long, may readily be pronounced by eye-view alone, extremely dull if seen transversely; Coal.Tar Colours.-Mr. W. H. Perkin, F.R.S., the but remarkably bright, pungent, and star-like, if looked at discoverer of mauve, the first colour produced from coal. end.on. The true test is, however, the result of actual | tar, is about to read two papers before the Society of Arts spectroscopic observation.
on the 8th and 15th of May, in which he will give a full Viewed transversely, to the line of electric light, the history of these colours, their chemistry and their techni. spectrum of “air,” simple atmospheric air, with a prism
pheric air, with a prism cal applications. of 3° dispersion, begins inside the scarlet hydrogen line; and from thence to the lavender-grey, or other end of the • Experiments were made first of all as to the best area of a circu.
lar bore for the capillary; and proved that there is a lower limit
which should not be passed if the full, as well as most intense, iilu. of hazy, indistinct, unsatisfactory bands. But viewed end.
mination derivable from any given electric current is to be preserved ; on, the spectrum of the very same air tube, with the same and at the same time, there is an upper limit of area where the light, spark and same prism, begins 18 lines or markings outside though abundant, becomes too faint and diffuse.
Further experiments were then made in flattening the most desirable the scarlet hydrogen; and in the whole spectrum shows
| areas of bore (as so often practised with thermometers), and adapting 221 measurable items, many of them being vividly sharp
such flattened bore to the direction of the spectroscope's slit, in order lines.
to have a taller spectrum. But though the spectrum was thereby Next, on increasing the prism power to a dispersion of
made taller, and its lines longer, the author found such bores (on the auctore
more often doceed with pague. ad. 22° between A and H, but everything else remaining the
ventitious particles; and after a little practice, he did not find the same, the spectral lines were found so multiplied that 400 greater length of lines necessary to accurate micrometer observation : were quickly measured in a space where our first attempt while in proportion to such extra length, they waste the light wbi h
might otherwise be better employed. Whence he inclines, after all, had only 38. But I do not claim that all those 400 are truly
to circular bores, as more easily manufactured, and more certainly air spectral lines; only that they were lines distinctly tested as to whether they correspond, or not, to any proposed general seen in a well lighted tube, said to contain chemically the standard of size. A standard of compound shape, as well as size, is purest possible "air-vacuum.” And in fact I stopped
far more difficult to have universally kept to.
# For the ordinary tube-glass, so large an extra-dose of carbonate where I did, in the green, instead of going on to measure of soda, I am told, is usually introduced into the melting pot (to proabout 1000 more lines that were waiting in the blue and mote easy working at low heat and economise coa!), that the glass violet, because it presently appeared most indubitably,
becomes sa lly hygroscopic, ard depositions of both water and
carbonaceous matter form in the capillaries, and can never be com. that some of the lines just entered, instead of belonging 'pletely cleaned out.
New Form of Wash-Bottle. Igo
May 2, 1879. EXTINGUISHING FIRES IN TAR
the action is so powerful in a comparatively open space, DISTILLERIES, &c.
and with such a refractory substance as burning pitch. It
would seem, also, that the extinguishing power in the By WATSON SMITH, F.C.S., F.I.C.
liquor would be even further called forth by a more intensely
hot fire, for here, in all probability, the ammonia would be It may not be known to all tar distillers that in cases of decomposed, and the generated nitrogen and hydrogen fire on their premises their best remedy usually lies close / gases would help to swell the volume of non-supportive at hand, and this I will shortly endeavour to demonstrate | gas, displacing the air, and so choking out the combustion. from a basis of experience and fact. In the first place, however, it may be well to state that as a rule the tar distiller cannot get any fire insurance company to insure him, and it will therefore be seen that it is a matter of no light A NEW FORM OF WASH-BOTTLE. importance to be possessed of a ready and efficacious method of subduing the dread element, when it breaks out
By F. R. MALLET, beyond its due bounds. This remedy lies in the crude
Geological Survey of India. ammonia-water, otherwise known as gas-liquor, which almost every distiller works up conjointly with the tar, and if in some cases this be not so, it would be little en
'; In the Chemical News, vol. xxxix., p. 19. Mr. M. H. cumbrance, and well worth while, to obtain and keep a
Foye gives a description of an ingenious form of washstock of, say, 1000 gallons of this gas-liquor. The way in
bottle, the special feature of which is the introduđion of which I first became aware of the eminent extinguishing
| a short piece of india.rubber tube in the course of the
mouth-tube. By compressing this between the cork and powers of gas-liquors (now several years ago) is as fol. lows :-A quantity of pitch was being run from a tar-still
the finger communication is cut off between the mouth into the pitch-house, in which it is allowed to stand for
and the bottle. The advantages of this are (1) that after
blowing into the bottle and then compressing the rubber some hours, to allow most of the noisome vapours to con. dense. By some means a flame came in contact with
tube, the pressure of air is sufficient to maintain the jet
of liquid for some time; this jet can be instantly stopped the vapours, an explosion occurred, and in a moment the roof was blown off, and the whole mass of molten pitch ablaze. Water, though thrown on it in quantity, seemned to avail nothing, and at last the supply accidentally ran short. Almost in despair, the pumps for raising the gasliquor into the ammonia-stills were adjusted so as to deliver a jet of the liquor upon the fiercely-burning pitch: the expedient acted like a charm, and the fire was quickly amothered.
I think there is considerable probability that at the high temperatures attained in some fires even the ammonia it. self would be decomposed, with liberation of nitrogen and hydrogen gases, which in addition to the volumes of car. bon dioxide and steam, choke out the flame by simple dis. placement of air. It might be said that if hydrogen and nitrogen be so liberated together, these, together with the H2S also set free, would do much to neutralise the effect of the non-combustible gases. Not so, however, for let there be but enough incombustible gas present, as there is, to displace the air, or to choke by excessive dilution the little which may remain or diffuse, then the combustible gases present, thus for the time prevented from burning, would assist in smothering the flame (being non-supporters of combustion) with as good a will, if one may use the expression, as the incombustible ones.
I would strongly recommend every tar distiller, who also works up gas. liquor, to so arrange his pumping.gear that he may be able to throw jets of this liquor into any part of his yard or works where fire might break out and prove disastrous. If gas-liquor be not worked, then I would advise that a stock of, say, 1000 gallons be purchased. In a small works this might be advantageously stored in a tank or old boiler mounted on brickwork, at such an altitude as to give pressure enough to furnish a good jet for service below when required. Of course this reservoir should be covered to prevent evaporation.
Looking at the frequent occurrence of disastrous fires in cotton-mills, especially those of Lancashire, I wrote some years ago to an eminent local paper, strongly recommend. ing that the owners of cotton-mills should set tanks on the tops of their mills, and furnish these with supplies of am. moniacal gas-liquor, to be always ready for service. I gave, too, a short description of the best way of arranging pipes to these different rooms. The gas-liquor itself, by careful manipulation, may be pumped off very fairly clear, by releasing the rubber tube. (2.) That steam or un. and free from tarry matter. Of course, besides to fires in pleasant gas is prevented from passing from the bottle cotton-mills and tar-distilleries, this mode of fire-extin&ion into the mouth; and (3) that when pouring liquid out of might be all but universally applied. It may, indeed, be the mouth-piece the flow can be accurately regulated by readily imagined how a jet of the liquor thrown into a pressure on the rubber tube. burning room would act, the space being so enclosed, wl.en" On proceeding to make a wash-bottle according to the
instructions given by Mr. Foye, it struck me that, for use
EXPLOSIONS IN FLOUR MILLS. with hot or unpleasant liquids, some improvement would be effected by combining Mr. Foye's plan with that of
By H. W. LANGBECK. another form of bottle, which is described in Prof. Thorpe's “Quantitative Analysis ” (p. 55). The special feature of In the Annales de Chimie et de Physique there appeared, this latter form consists in the attachment to the bottom last year, a communication from L. Smith to Dumas of the mouth-tube (a b) of a valve, constructed of a piece concerning the explosive mixtures of finely-divided organic of rubber tube (b d), closed at the lower end by a bit of substances and air, especially of flour and air in some mills glass rod (c d), and provided with a slit (e), which remains at Minnesota. Mr. Smith supposes that meal.dust diffused closed except when the mouth-piece is blown into. in the open air was inflamed through the heat produced by
The advantage of this form of bottle is that unpleasant the friction of the millstones turning with great rapidity. gases are completely cut off from the mouth-piece (a). I think I am justified in opposing that explanation and But there are the defects (1) that it cannot be used for substituting another cne. hot water, because the only exit from the bottle being by Years ago I visited a friend, proprietor of a steam-mill, the jet-piece (hi), as soon as the water approaches the and there I noticed that the grains crushed between the boiling-point the pressure of steam causes it to dribble or millstones produced a smell like that of impure hydrogen. squirt out of the jet ; ar.d (2) that in the case of cold I called my friend's attention to the danger that might liquids, after the bottle has been blown into the jet of arise from want of sufficient ventilation, but laughingly liquid continues until the elastic force of the air inside he replied that there was nothing to fear. I forgot the has been expended; hence the jet is not fully under matter until the above-mentioned explosion reminded me control.
of it. In order to convince myself of the correctness of In Mr. Foye's bottle the jet is completely under con- Mr. Smith's supposition, I put some meal-dust, previously trol. In the case of hot water, however, the mouth-piece heated, in a dry bladder, blew air into it, and having dif(a) is the exit for escaping steam, and hence, although fused the dust by shaking, I directed the point of a gas. this steam can be cut off before applying the lips, the fame by means of a blow pipe into the opening of the mouth-piece has already been rendered more or less hot. bladder (an electric spark would have been preferable, but With unpleasant gas, after the rubber tube is closed, the was not at hand). No explosion took place. I allowed, mouth-piece above the rubber tube still contains some of then, coal-gas to enter the bladder, and repeating the exthis gas, which is free to enter the mouth. Forgetfulness periment, a violent detonation was the expected conseto remove the lips before releasing the rubber tube will quence. Meal dust diffused in a balloon, and blown allow gas or steam from the bottle itself also to enter the through a gas-flame, was ignited; but this was, of course, mouth.
not the condition on which the explosion at Minnesota The modified form of bottle that I have adopted is took place. But what may be the source of the hydrogen, represented in the accompanying sketch. The mouthif indeed present? The amount of fat in wheat flour piece has the valve (b d) attached to the lower end. fgi varies between I to 1'9 per cent, of bran 4 to 4'7 per cent, is a jointed jet-piece of the ordinary form, the small glass of maize, perfectly dried, 8 to 9 per cent. Is water pretube (i h) being inserted into the large one ( h), with a disposed to oxidise the fat through heat produced in bit of rubber tube (g h) between. jk is a third tube, grinding, thereby setting free hydrogen ? Has the change penetrating the cork obliquely, and bent at k at an acute of a small amount of starch into dextrin and glucose during angle. A piece of rubber tube (!) is, at one end, slipped the grinding process something to do with it? on to k and terminated at the other by a short bit of glass tube (m). Outside the rubber tube (1) is one of con. siderably larger diameter (n). If such a bottle be used for hot water, the steam escapes from m, and hence the CONVERSAZIONE AT THE ROYAL SOCIETY. mouth-piece (a) remains perfectly cool. On compressing the tube n with the forefinger and blowing into a, a jet issues from i, which continues after the removal of the On Wednesday evening last the President of the Royal lips until the elastic force of the air in the boitle is ex Society, Mr. W. Spottiswoode, gave a Soirée at Burlington pended, but which can be instantly stopped by releasing House, which was largely attended. The novelties exn; the use of the outer tube (n) is as a non-conductor.
hibited in the various rooms attracted great interest. In The tube I becomes hot from the issue of steam, but n, the first room were exhibited Mr. Crookes's Exhausted being separated from it by an air space, remains sufficiently
| Tubes and Apparatus illustrating various phenomena con. cool for the finger to be placed on it without discomfort. nected with Molecular Physics in High Vacua. The A bottle of this sort must, of course, have the neck
following is a description of the experiments which were wound round with twine or other material to keep the shown :hand cool. If the bottle be used for cold liquid only n| 1. Dark Space round the Negative Pole.—When the may be dispensed with.
spark from an induction coil is passed through an ordinary By shifting the valve (6 d) from the mouth-tube to the vacuum tube, a dark space is seen round the negative pole. tube j, the bottle may, if desired, be instantly converted | The shape and size of this dark space do not vary with into one on the ordinary plan, or if this be considered the distance separating the poles; nor, only very slightly, unnecessary, the bend of the tube at j (which must be with alteration of battery power, or with intensity of made after the tube. has been inserted into the cork) may spark. This well-known dark space appears to be a layer be dispensed with.
of molecular disturbance identical with the invisible layer For cold water Mr. Foye's bottle is preferable, as liquid of molecular pressure or stress, the investigation of which can be poured out by the mouth-piece and the flow ac. has occupied the exhibitor some years. curately regulated, which cannot be done with that I have 2. The Electrical Radiometer.--An ordinary radiomete described.
is furnished with aluminium cups for vanes. The fly is Calcutta, March 27, 1879.
supported by a hard steel cup, and the needle point.on which it works is connected with a platinum terminal sealed into the glass. At the top of the radiometer bulb
a second terminal is sealed in; the radiometer can there. The Government Patent Bill.-A paper on the fore be connected with an induction coil, the movable fly Government Patent Bill" will be read before the Society being made the negative pole. At low exhaustions a of Arts on Wednesday evening next, the 7th inst., by W. velvety violet halo forms over each side of the cup. On Lloyd Wise, A.I.C.E. F. J. Bramwell, F.R.S., in the increasing the exhaustion the dark space widens out, Chair.-Beri der Deutsch, Chem, Gesell,
I retaining almost exa&ly the shape of the cup; the bright