Obrazy na stronie
PDF
ePub
[ocr errors]

Chemical Notices from Foreign Sources. 32

CHEMICAL News,

July 21, 1876. is, on the average, from forty to sixty minutes. With a A Differential Radiometer.-M. W. de Fonvielle.set of ten vats of 6 cubic metres it is possible to lixiviate The author has had constructed a radiometer, the discs of in fifteen hours 50 tons of 1000 kilos. each of fresh weed. which (of mica) are coated on both sides with lampblack, The second stage of the operation consists in evaporating and the case is blackened in the same manner over half to dryness the successive saturated lyes, and then cal- its surface. If the light is received perpendicular to the cining very slightly in presence of a slight excess of car- diametral section which separates the transparent hemibonate of potash, carrying the process to the commence- sphere from the darkened hemisphere the apparatus ment of the aqueous fusion. This procedure yields a remains motionless. If, on the contrary, the diametric soda very rich in soluble salts, in utilisable salts of potash plane is inclined to the left, the left-hand discs, more strongly (chloride and sulphate), and in alkaline iodides. The in- illuminated than those on the right, are repelled more cineration process gives, on an average, 15 per cent of energetically, and the radiometer takes a regular movepotash salts, and i per cent, at the outside, of iodide. The ment from left to right. The same phenomenon is new process yields 45 to 50 per cent of utilisable salts of observed in the inverse direction if the diametric plane is potash, and 27, 3, or even 5 and 6 per cent of iodide if | inclined to the right. The rotation is the most rapid the weeds have been well selected. The residual weeds possible when the diametric plane is rendered parallel to are still applicable in agriculture.

the rays of light which illuminate ths apparatus. Certain Experiments made with the Balance of Researches on Cypressus Pyramidalis.-M. Hartsen. Crookes.-M. G. Salet.—The author makes the discs of his radiometer of mica, and blackens both on the same Les Mondes, Revue Hebdomadaire des Sciences, side. He considers his results difficult to reconcile with

No. 9, June 29, 1876. the idea of a direct impulse due to light or to the ether, The Radiometer of Mr. Crookes.-Since the combut contrary to the theory which seeks to explain the mencement of the century much attention has been paid inovements of the radiometer by the disengagement of to the electric, magnetic, and mechanical action of light. gases condensed on the discs. Can the minimum quan- | The author in the third volume of his Repertoire tity of gas which remains in an apparatus exhausted with d’Optique" has analysed at length the experiments made such care suffice to occasion the movement, according to by Sommerville, Barlocci, Valt, Zantedeschi, Matteucci, Tait's theory?

Faraday, Davy, Moleyns, &c. Valt alone (p. 1011) Certain Derivatives of Normal Pyrotartaric Acid, obtained under the action of light the orientation, if not the -M. Reboul.-A description of the salts of zinc, copper,

rotation, of suspended discs, all other attempts having led lead, silver, soda, and of the normal pyrotartrate of ethyl to negative results. If M. Recamier caused his discs to

Volumetric Determination of Formic Acid.-MM: revolve under the influence of light under closed bells, it Portes and Ruyssen.—The authors remark that the quan- Mr. Crookes obtains indefinite rotations with extreme

was certainly because he set in adion gaseous currents. titative determination of formic acid in acetic acid ha certain importance in solving the problem of the deter: facility. His experiments, which constitute one of the mination of wood-spirit in spirit of wine. They pour into

most brilliant discoveries of the age, engage all minds, and a Alask containing 5 grms. acetate of soda 25 c.c. of a

are like an enigma on which no one has yet given the final solution at 10 per cent

of the mixture in question, and add decision. It is time for the Academy of Sciences to elect 200 c.c. of a solution of sublimate at 4'5 per cent (9 grms.).

a commission to study these phenomena from all sides. It is heated from one hour to an hour and a half in the water-bath until the supernatant liquid has become per

MISCELLANEOUS. fealy limpid. The wl.ole is then made up to the volume of 500 c.č. and filtered. It is then ascertained, by means Death of Dr. Hearder.- The Plymouth correspondent of a graduated burette, how much of the reduced liquid is of the Pall Mall Gazette telegraphs on the 17th inst.,required to saturate i grm. of potassium iodide. The

Dr. Jonathan Hearder died last evening from a sudden number found by calculation must be corrected by the addition of one-fourth.

He was the last remaining of the paralytic seizure.

group of men who made Plymouth famous for scientific Arragonite observed on the Surface of a Meteorite. discoveries forty years ago. "Dr. Hearder's researches in – J. Lawence Smith.—Arragonite has been found as an science, especially in connection with electricity and incrustation on certain specimens of meteoric iron from chemistry, were not extensive, but profound. He had the so-called Mexican Desert (Bolson de Mapini), situate made his name well known among the leading physicists in the provinces of Cohahuila and Chihuahua. The author not only of England but Europe and America. Almost is of opinion that the incrustation has been formed since at the outset of his scientific career an accident befell the fall of the meteorite.

him, which, in the case of a less determined lover Compounds of Carbon Found in Meteorites.-J. of knowledge, would have put an end to reseach. Lawrence Smith.-The author has pursued his studies on

While experimenting with a fulminating compound he the crystalline hydrocarbides derived from terrestrialirons was deprived of sight by an explosion. Yet" his chief and doubtful meteorites, like that of Ovifak, searching for honours were won after that event.

He was inti. hydrocarbides in the carbon combined with these irons. mately associated with Sir William Snow in his elec. That of Ovifak contains a notable proportion of this car

trical researches. His own discoveries and inventions bon. There was in these irons a substance similar to that in connection with the induction coil and the theraalready found in meteoric graphite and carboniferous peutic appliance of electricity were many and valuable. meteorites. It has the same strong odour, and crystallises Dr. Hearder was one of the earliest to perceive that a .n small needles. If heated on platinum-foil it melts telegraphic cable across the Atlantic was not only im. readily, and at higher temperatures it burns with a flame, portant, but practicable, and he invented a cable for which and disappears.

he took out a patent, a slight modification of which was Use of Calcium Chloride in Watering the Paths of ultimately adopted for Atlantic telegraphing. Dr. Hearder Promenades and Public Gardens.-M. A. Houzeau.- had a marvellous memory, and was never at a loss for a The nature of this paper may be understood from its title. fact or a date. He was a zealous lover of all matters

connected with local antiquities and history. The bent of Experimental Researches on the Action of Aniline Dr. Hearder's mind was quite as practical as it was inves. Introduced into the Blood and the Stomach.-MM. ligative. He invented special forms of stoves, gas and V. Feltz and E. Ritter.—The authors describe the symp. other, and was a specialist in the matter of fishing gear. tons produced, both in men and dogs, by small doses of He not only contrived medical electric apparatus, but magenta. It is fortunate for them that they are not resi- practised as a medical electrician, and was electrician to dent in England.

the South Devon Hospital.

CHEMICAL News,

Development of the Chemical Arts.
July 28, 1876.7

33

REPORT THE CHEMICAL NEWS.

ON THE

DEVELOPMENT OF THE CHEMICAL ARTS VOL. XXXIV. No. 870.

DURING THE LAST TEN YEARS.*

By Dr. A. W. HOFMANN.

(Continued from p. 26.)
INFUSORIA AND NITRATES.
By T. L. PHIP ON, Ph.D., F.C.S., &c.

Chlorine, Bromine, Iodine, and Fluorine.

By Dr. E. Mylius, of Ludwigshafen. Some very interesting observations regarding the reduc- Regeneration of Manganese according to Weldon.-Re. tion of nitrates by bacteria have recently been made by cently Weldon has completely succeeded in attaining the M. Meusel. It has been long believed that the nitrites object aimed at by so many. C. Binks and J. Macquent found in waters are due to the oxidation of ammonia, but had previously sought to revivify the chloridě by precipithe author just named has proved in a satisfactory manner tating it with the quantity of hot milk of lime needful for that they are not necessarily so produced. Water con- decomposition, passing a current of hot air through the taining no compound of nitrogen except some alkaline liquid, and utilising the precipitate thus converted into nitrate was found after a certain time to contain no ni- higher oxides in place of fresh manganese. But Weldon trites: this reduction was the effect of numerous bacteria was the first who succeeded in making the process techvisible in the microscope. It was stopped at once by nically applicable. His most essential improvement conphenol, salicylic acid, benzoic acid, alum, and salt. The sists in the point that he uses not a sufficient quantity of following experiment shows under what circumstances milk of lime, but an excess. Considering the importance this phenomenon occurs :

which Weldon's process for the regeneration of mangaA little pure water, containing some bacteria, has an nese has already attained in the modern manufacture of alkaline nitrate added to it. At first there is no reduction, chlorine, since its commercial value is fully proved by its but after the addition of certain organic substances, more introduction in many establishments, especially in England, especially carbohydrates, such as sugar, &c., nitrites are it may be considered permissible to describe its principles produced at once and rapidly. Recently distilled water, at greater length than the procedures already mentioned. mixed with sugar and a little alkaline nitrate, then boiled The following account is founded partly on Mr. Weldon's in a long-necked flask, the end of which is closed during paper in the CHEMICAL News (vol. xxii., p. 145), and partly ebullition, showed no reduction after many weeks. on his letter to Dr. A. W. Hofmann, dated March 12th, The conclusions drawn from these experiments are

1874. That the nitrites found in ordinary waters are due to Whilst, according to Weldon, hydrated manganous bacteria ; that the latter are the agents of the transmission oxide diffused in water can be only oxidised to manganic of oxygen, even when this substance is combined, and oxide, Mn2O3, by forcing oxygen through the paste, it is that this is probably the reason they are so dangerous to possible, in the presence of lime or magnesia in excess, to

convert the whole of the manganese into peroxide. The On repeating these experiments with very dilute solu. latter remains united with the lime as

a compound, tions of permanganate of potash, without the addition of CaO, MnO2, or CaMnO3, calcium manganite. This may any organic substance, I find the bacteria killed simulta; be regarded either as an analogue of the hydrated perneously with the reduction of the salt. I have also found oxide of manganese, or as manganic oxide, Mn203, in that when a little too much nitrate of potash exists in the which an atom of manganese is replaced by lime. "Hence. water no reduction takes place, and the bacteria are also it follows that i mol. calcium manganite requires exactly rendered immovable.

as much hydrochloric acid in the preparation of chlorine Now M. Meusel has also asserted that nitrates are use. as i mol. of Mn203. Nevertheless it is advantageous to ful as manure, not only by the nitrogen they contain, but oxidise the manganous oxide with the aid of lime, since, on account of the oxygen they supply to bacteria, which in the first place, the same amount of manganese perenables the latter to destroy cellulose, &c. If this is the forms double the duty as if it had been only converted case, it would appear, at first sight, that nitrate of soda into manganic oxide; and, secondly, the oxidation is would prove a more valuable manure than sulphate of am- effected with far greater ease in presence of an excess of monia. But not long since I applied sulphate of ammonia lime. This is probably because manganous oxide is someand nitrate of soda to two small plots of the same pasture what soluble in pure water or in solution of calcium land in such quantities as to supply the same amount of chloride, and thus retards the oxidation. At least it has nitrogen in each case. 8} cwts. of nitrate of soda, and been experimentally proved that salts of manganese deci61 cwts. of sulphate of ammonia were used in this experi- dedly retard the progress of oxidation. If, on the other ment, and the result was as nearly as possible identical in hand, there is an excess of lime, a brown solution of cal. both cases. As with the bacteria, when either substance cium manganite is rapidly formed, which, as experiments was applied in excess the grass was killed, and turned prove, greatly accelerates the absorption of oxygen by the brown or yellow within three days. When applied in the deposit of manganous oxide. most favourable proportions the yield in both cases was Latterly, however, it has been found possible to comalmost identical." Now 64 cwts. of sulphate of ammonia plete the oxidation of the manganese by an increased supplied no available oxygen, whilst the 81 cwts. of nitrate current of air along with a diminished dose of lime. of soda supplied about it cwts. of oxygen, the quantity of Under these circumstances we may assume the formation nitrogen being the same. Yet there was no apparent re- of an acid manganite, CaMnO3, H2MnO3. In fact, in exsult for this difference of oxygen.

ceptionally successful operations, calcium manganite has Now, if M. Cloëz's theory is true, that C, H, and N are been obtained in which only i mol. of lime was present assimilated by plants as CO2, H0, and NO5, and that NH3 to 2 mols. of peroxide of manganese. In most cases the in the soil or the manure becomes Nos to be assimilated, manganese paste has the following composition :then the atmosphere would have supplied to the sulphate of

0.80 MnO2, ammonia the extra il cwts. of oxygen in question. This,

Mno, of course, would require rather more time, and such, in

028 = Cao. fact, was the case in my experiments, the nitrate being the quickest of the two by about eight days.

* "Berichte über die Entwickelung der Chemischen Industrie Laboratory of Analytical Chemistry,

Während des Letzten Jahrzenends."
Putney, London, S.W.

+ Technologiste, 1862,

Sept. 27. Wagner, Jahresberichte, 1862, 237.

man.

020 =

CHEMICAL NEWS, Erythrogen and some of its Compounds. 34

{

July 28, 1876. That the lime in the paste is chemically combined, and / When cold pour off the naphtha, and having wiped the does not exist as a mere admixture, may be inferred be surface of the amalgam with a dry cloth, transfer it as cause the product is perfectly neutral, and because lime quickly as possible to a dry stoppered bottle, and add to it cannot be withdrawn from it by a solution of sugar. The a quantity of bisulphuret of carbon equal to about three manganous oxide can also be oxidised by air when the times the weight of the potassium employed; then shake lime is replaced by baryta, strontia, or soda.

the whole well together until the mixture becomes solid, On a practical scale the process is carried out as fol- when it must be set aside for a few hours to cool and comlows:- The manganese liquor from the chlorine stills is plete the combination. After this, the surplus bisulphuret let off into tanks provided with agitators. In these it is of carbon is to be driven off by a current of air, and the treated with finely-divided carbonate of lime, to neutralise erythride of potassium separated from the mercury by the free acid and to throw down any iron which may be water and filtration in the usual way. But it is worthy of present as oxide. The liquid is then pumped off into notice that a part of the mercury, under the influence of settling-vats, in which it is left to become clear. Hence the potassium, is converted into erythride of mercury at the clear neutral solution is run into the oxidiser-an iron the same time, and this holds out a hope that such metals cylinder, 3•66 metres in diameter and 6.61 in height. Into as lead and antimony in a very minute state of subdivision this, near the bot:om, opens a narrow pipe which conveys may be useful in purifying coal-gas from bisulphuret of steam, and one or more wider air-pipes. After the liquid carbon; and, in fad, I am now actually trying the pyrohas been heated to 55°—75° by a current of steam, milk phoric mixture of lead and charcoal formed by heating of lime, prepared from finely-sifted hydrate of lime, is run the tartrate of lead, and it seems to promise well. When in as rapidly as possible, whilst air is simultaneously the hydro-erythric acid is thrown down by acids from the forced in until no manganese can be detected in the solution of erythride of potassium, much of it is decomfiltrate. This occurs when not only all the manganese is posed in carbonic acid and sulphuretted hydrogen, except converted into manganous oxide, but when an excess of at a very low temperature ; but in either case it forms a hydrate of lime is already present. For this purpose fixed, chocolate-red, granular powder, most remarkably 1:15 to 1:45 mols. lime are required to i mol. manganese. like selenium. To be continued.)

Sandy, Bedfordshire, July 22, 1876.

ERYTHROGEN AND SOME OF ITS COMPOUNDS. ON THE AMALGAMATION OF IRON AND OF

SOME OTHER METALS.*
By LEWIS THOMPSON.

By P. CASAMAJOR. When we look at the vast extent of our gas making in Ar the last meeting of this Society I was to speak to you an artificial cry about the " sulphur in gas," we may well of the hour from reading the paper I had ready for you. wonder that so little has yet been done to remove the exaggerated defect. But this display of inventisen povertynia about iron amalgam, one of which is that most of the the possibility of doubt, that Governmentala interference lished, although in a very succinct form, about nineteen with any manufacturing industry is not a rapid road to improvement.

About twenty-nine years ago I first became aware of the appearing before you to night if I had not found that the fact that such articles as liquor ammonia and carbonate of subject is deemed by chemists, to whom I have shown

samples of amalgamated iron, to be not only new, but ammonia, when made direct from gas-liquor, always con

very interesting. I have, besides, much new matter to tained more or less of a peculiar red substance, which con. taminated the ammoniacal products, and rendered them gamating iron, which is so simple and economical that all

communicate, among which is a new process for amalunfit for use in silk dyeing and some other arts; and a

the other processes are rendered obsolete and useless. careful examination convinced me that this red matter

That iron will combine with miercury is known to all was not sulphocyanide of iron, but had some mysterious chemists, although it is not deemed an easy operation, connection with bisulphuret of carbon. I have often sepa. and we may find in the books several processes for accomrated this red matter from gas-liquor, and also from gas. plishing the combination. One of these, which I believe lime refuse, and both shown and given it to several of my is due to Sir Humphry Davy, consists in immersing friends, but it has always been so mixed with other im; sodium ' amalgam in a saturated solution of ferrous purities that no decisive opinion could be formed leded its chloride of sulphate. In another process zinc amalgam

in The mystery, however, appears to admit of solution if we

lution of ferric chloride. The filings become coated with suppose the bisulphuret of carbon to be a halogen body mercury. In still another process

, the electrolysis of ferlike cyanogen, and therefore capable of uniting directly rous sulphate gives iron amalgam when the negative practice by combining it to potassium, with whiçbuit forms sulting amalgam to enormous pressures a residuum of a compound remarkable for the blood-red colour of its pretty firm consistency is obtained, which is composed of solutions in water and alcohol, and therefore I propose to

about equal parts of iron and mercury. give the name Erythrogen (from " Erythros," red) to the

The processes of amalgamation which I am to describe Bisulphuret of carbon in its combination so lanido Herdhe to you this evening give products which have nothing in Erythric Acid to the acid set free from the solution of the common with these iron amalgams. The samples of iron erythride of potassium by an acid.

, I Not to trouble your readers with any superfluous re

mercial wrought-iron, from cast-iron, and from steel, marks , I will describe in as few words as possible

thic mode without altering the original shape of the material, a: hydro-erythric acid and other compounds may be produced zinc which we use in voltaic batteries. To make erythride of potassium, we must begin by give you a succinct

account of the researches of Cailletet,

Before giving you the results of my labours I must making an amalgam of potassium, consisting of about part by weight of potassium and 150 of mercury, whịch

Read before the American Chemical Society, Juno yst, 187 is easily done by fusing them together under naphtha. / Çommunicated by the Author,

July 28, 1876.
, ,} Amalgamation of Iron and Other Metals.

35 which came to my knowledge as follows:-Before pre-termine the combination of iron with mercury. Although senting myself before you at the last regular meeting it I now use a much simpler and a cheaper process, which I had been my endeavour to ascertain whether the results I propose to describe in a few minutes, there are some was to announce were really new. Neither by my own points in connection with the alkaline amalgams and with exertions nor by inquiry from other chemists had I been the action of the voltaic current which may be studied able to discover that I had been forestalled, and had I with advantage. confined my attention to iron I would not have been Amalgam of potassium, which I first used for amalaware—perhaps even now-of the existence of a prior gamating iron, behaves in every way like amalgam of claimant.

sodium. Sodium, however, behaves somewhat differently Having turned my attention to aluminium, I had occa- from potassium towards mercury, the combination with sion to consult Watts's “ Dictionary of Chemistry," on sodium taking place with greater violence, being accomthe subject of aluminium amalgam, and came upon the panied by a flash of sodium light and the escape of following :" According to Cailletet (Comptes Rendus, alkaline vapours which are far from agreeable. These vol. xliv., p. 1250, aluminium (also iron and platinum) unpleasant manifestations may be reduced to a minimum may be superficially amalgamated by contact with ammo- by combining sodium at first with a very small quantity nium or sodium amalgam and water; also when it is im- of mercury-a quantity not more than a fifth of the mersed in acidulated water in contact with metallic weight of the sodium.' This gives rise to a violent remercury, forming the negative electrode of a voltaic action, but subsequent additions of mercury produce less battery."

and less effect, while, by bringing small pieces of sodium On consulting the 44th volume of the Comptes Rendus successively into a comparatively large mass of mercury, I found, at p. 1250, a memoir presented to the Academy every fresh piece of sodium produces the same effect as its of Sciences by Messrs. Chevreul and Dumas, at the sitting predecessor. of June 15th, 1857, the title of which is “On the Influence If the sodium amalgam has sodium enough in it to of Nascent Hydrogen on Amalgamation,” by M. L. Cail. make it pasty, it will cover iron with a silvery coat. This letet. The author uses ammonium amalgam, with which coat may be rubbed off, leaving the oxidised surface unhe agitates pieces of iron, aluminium, or platinum, and altered. If brought in contact with water, or, still better, he finds that these metals become coated with mercury. with a solution of sal-ammoniac, the sodium amalgam is The amalgam of sodium produces the same effect, only decomposed and the mercury will sink into the iron. If water is necessary to the reaction. If the surface of the the sodium amalgam is liquid it will adhere in little drops sodium amalgam is covered with naphtha no action takes all over the surface of a piece of iron shaken up in it; by place, but one drop of water is sufficient to produce the the action of water, of acids, or of sal-ammoniac, the desired effect.

droplets will spread on the iron, which will become amalIf in a vessel containing mercury and acidulated water gamated. we place the electrodes of a battery, and if the negative Ammonium amalgam will give up its mercury to iron electrode be a piece of sheet iron in contact with mercury, when rubbed up with it very persistently. Even then the iron will be amalgamated as soon as hydrogen appears there are in every piece of iron certain spots where the on this electrode.

mercury will not adhere. The intervention of acidulated From these experiments Cailletet concludes that amal- water, by decomposing ammonium amalgam with great gamation in these cases is due to nascent hydrogen, and energy, facilitates the amalgamation of iron in these difhe seems throughout his memoir to be so intent upon ficult portions. proving this point that every other circumstance is men. From the foregoing remarks you will understand that tioned in the most cursory manner. We may be allowed the maximum of good effect may be obtained from a certo doubt whether by covering sodium amalgam with tain amount of sodium by the following method of pronaphtha, so that when iron comes in contact with the cedure, while the combination of iron with mercury is amalgam it is already covered with a film of naphtha, we very thorough and rapid :—We take four porcelain dishes have placed the iron in the best condition to combine it and place them in a row, so that the piece of iron to be with mercury, and whether the non-combination under amalgamated may be placed successively in each. The these circumstances is very conclusive of the necessity of first dish contains a liquid sodium amalgam ; the second nascent hydrogen to determine the combination between a solution of sal-ammoniac; the third water, acidulated iron and mercury.

with either sulphuric or hydrochloric acid ; and the fourth The following experiment with a mercuric salt carries aqueduct water. The piece of iron to be amalgamated is more weight with it :-The author wishes to show that taken up with tongs, and agitated in contact with the soamalgamation, in the case of iron and platinum, is due to dium amalgam of the first dish. This operation covers it nascent hydrogen, and not to the ele&rical condition of with liquid mercury containing sodium amalgam. When the iron or platinum electrode. He takes the case of the the surface seems sufficiently coated the iron is left for a electrolysis of salts of copper, silver, and mercury, and few seconds in the solution of sal-ammoniac, on emerging recalls that at the negative electrode we obtain me- from which it is found covered with the curious and intetallic copper, silver, and mercury, but no hydrogen. If resting compound which we call ammonium amalgam. we have a salt of mercury subjected to a voltaic current, The piece of iron is placed next in the acidulated water, the negative electrode being made of iron or platinum, we and finally in aqueduct water, to wash off the acid. may notice after a while that globules of mercury appear This series of operations is generally sufficient to leave on this electrode, but they show no tendency to combine a good coat of mercury on a piece of iron. If there with it. If, now, the electrodes are withdrawn from the should be spots lest bare, a second series of immersions is mercury salt, and placed in a vessel holding acidulated generally sufficient to leave the surface perfectly covered. water, as soon as the voltaic current passes and hydrogen I need not say that the surface of the iron must be preescapes at the negative electrode the globules of mercury viously made clean by immersion in diluted acid. spread on this electrode, and it becomes amalgamated. By making the negative electrode of a voltaic battery

The above account of the memoir presented by Cailletet of iron, and placing it in contact with mercury and with contains substantially everything there is in it.' The cir- acidulated water, the iron will, after a time, become cumstance mentioned in “Watts's Dictionary,” that the amalgamated. I have obtained the same result by a amalgamation obtained on iron and platinum is merely single voltaic element, the positive plate of which is a superficial, does not appear, even by implication, in the piece of zinc and the negative plate a piece of iron, one original paper.

portion of which is in contact with mercury at the bottom Amalgam of sodium and ammonium, and the voltaic of the cup, the exciting fluid being acidulated water. An battery: these are the agents mentioned by Cailletet ; addition of chloride of sodium to the liquid in the cup these were also the agents that I used a month ago to de- I seems to hasten the reaction.

36
Measuring Air in Mines.

CHEMICAL NEWS,

July 28, 1876. Iron may be amalgamated also by the use of zinc If, however, two pieces of iron-one amalgamated an

ad amalgam. This process gives the best results, and ren- the other not-are connected by a metallic wire, the amalders superfluous all the other processes we have mentioned. gamated plate is attacked, and the other plate plays the The use of zinc amalgam for the purpose had been at part of a negative. tempted before, as, for instance, in the process I have In iron amalgam, made in the way I have described, mentioned where iron filings are rubbed with zinc amal. the quantity of mercury in combination is very small. A gam in presence of a solution of serric chloride, the re- piece of sheet iron, presenting on both sides a total suraction being assisted by heat. I also find in “ Watts's face of 3 square inches, was amalgamated and left to soak Dictionary” that, “ according to Aikin, iron amalgam is in mercury for over an hour. The mercury was then formed by the action of zinc amalgam on ferrous chloride." wiped off very thoroughly, and the piece of sheet-iron No particulars are given about this process, but the results weighed. The increase over the original weight was must have been, to say the least, difficult to obtain, as we 13 centigrammes, which showed an absorption of mercury find, immediately afer that, “according to Daniour, it equal to a little over 4 centigrammes per square inch. cannot be obtained in this way."

The increase of weight in this thin sheet of iron was only I came upon the process I am about to describe by a 35 per cent. Still in this sheet the fracture was silvery, mere chance. I was trying to test the soundness of the and globules of mercury stood on the rough edge of the theory of Cailletet, which attributes the amalgamation of fracture. iron to the presence of nascent hydrogen. In a beaker For the sake of comparison I treated a piece of sheet glass I had placed mercury, and over it acidulated water, zinc, of the same dimensions, in the same manner, leaving and also a horse-shoe nail of Norway iron, which rested it, however, only a few minutes in contact with mercury, on the mercury. A moderate escape of hydrogen took After rubbing off the excess of mercury, and weighing, place from the surface of the iron nail; but after twenty- was surprised to find a loss instead of a gain in weight. four hours no trace of amalgamation had appeared, which This was doubtless due to a certain quantity of zinc being showed very conclusively that unassisted nascent hydro- dissolved by the mercury. gen was certainly not sufficient to do the work. Having I must now, to fulfil the programme offered by the title to amalgamate a small piece of zinc for another experi- of this paper, speak to you of the amalgamation of some ment, I found that I had no other mercury within my other metals, by which are meant some of those whose reach than the one on which the nail of Norway iron point of fusion is very high, and which have always rested. As I had given up hopes of accomplishing any shown themselves exceedingly adverse to combining with thing by this arrangement, I had no scruple to use the mercury. Those that I have tried are platinum, pallamercury in this beaker glass, and in it I placed my piece dium, aluminium, nickel, and cobalt. Except in the case of zinc: the result was that the escape of hydrogen from of aluminium there seems nothing of peculiar interest to the nail increased very perceptibly, which circumstance notice about their amalgams, after what has been said of induced me to leave the zinc in the mercury. On looking iron amalgam. These metals all take mercury very rea. again at the iron nail I found it amalgamated and partly dily by the processes which are effective in the case of sunk into the mercury.

iron. Aluminium deserves mention on account of its ecTo amalgamate iron with zinc amalgam, mercury centric behaviour: it seems to take mercury in the same should be placed in a vessel and covered with dilute manner as the other metals, but shortly after being taken sulphuric or hydrochloric acid. If, now, a piece of iron out and dried it becomes very hot, the mercury seems to is agitated, in contact with the mercury and the acid, no boil, and the aluminium remains covered with a chalky combination will take place; but if pieces of zinc are crust. On brushing this off, the metal is found beneath placed in the mercury, in a few minutes iron placed in the without a sign of amalgamation. above conditions will become coated with mercury. If In conclusion, I will point out that two inquiries suggest after a while the power of the mercury seems to decline, themselves in connection with these amalgams. One re, more zinc must be added. The zinc is only attacked lates to the determining cause of these combinations, and when iron, or some other metal more electro-negative the other is whether these amalgams-particularly amal. than zinc, is brought in contact with the zinc amalgam gam of iron-can be applied to useful purposes. To both and the acid, so that the expense in zinc is very slight. these questions the answer is, that I have nothing satis

The coat of mercury left on iron by the various agencies factory to offer, although great many things suggest themI have mentioned is not a superficial layer, for the mer- selves as plausible. I am sure you will readily excuse me cury sinks into the metal, modifying its physical and from presenting theories that are merely plausible, as to chemical properties. In the case of pure soft iron it is the cause of these phenomena, and feel equally certain difficult to notice any decrease of tenacity after amal- that I need offer no apology to this enlightened auditory gamation. With hard-tempered steel, however, the in- for calling their attention to these combinations of mer. creased brittleness is very marked. In the case both of cury with iron and other metals, because these have not iron and steel a fresh fra&ure shows that mercury has yet become of practical utility, although it may be befitpenetrated deeply into the metal. of the chemical change operated on iron by amalgam- | has been performed.

ting to offer an apology for the manner in which the task ation I can call attention to only one point, which is the analogy which exists with the properties of zinc amalgam. When a piece of zinc* has been amalgamated it is

ON MEASURING AIR IN MINES. not attacked by acids as readily as zinc free from mer. cury; but if a piece of amalgamated zinc is connected to

By JOSEPH DICKINSON, F.G.S., a piece not amalgamated, the amalgamated zinc becomes

H.M. Inspector of Mines. the positive plate in a voltaic couple. These properties

(Concluded from p. 27.) of amalgamated zinc are found, although in a less degree, in amalgamated iron. Two pieces of sheet iron, pre. With such a wide choice of anemometers, let it not senting exactly the same surface, were placed in diluted however, be supposed that there is no difficulty in ascer. sulphuric acid, so that the action of the acid was exactly taining the true average velocity of some air currents. It the same on each. One of these plates was amalgamated, is only when the current is regular that implicit reliance the other not. After prolonging the action for over two may be placed upon such instruments. In an intermitthours, it was found that the amalgamated plate had lost ing current the pulsations are shown plainly enough by two-thirds as much in weight as the other.

either the counterpoised fan-plate of the Dickinson ane.

mometer or the pendant of other similar instruments, and This observation relates to impure zinc. Amalgamation makes * This is more easily noticed with steel than with pure soft iron. impure zinc bchave towards acids like pure zinc.

+ A Paper read before the Manchester Geological Society,

« PoprzedniaDalej »