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Rock-salt, 20 millims. thick, not very clear
Rock-crystal, in two pieces, 42 millims. thick

Talc, clear but very dark, 1'25 millims. thick..
Plate glass, white, 2 millims. thick, one piece
Ditto, two pieces ..
Ditto, three pieces
Ditto, two pieces, enclosing 8 millims. water..
Plate glass, of a greenish colour, 10*5 millims.)

thick ...
Ditto, 20 millims. thick
Alum, a clear plate, 5 millims. thick
Plate glass, slightly greenish, 40} millims., and

clear alum plate, 8} millims. thick
Calc spar, 27 millims. thick
Very thin film of mica
Ammonio-sulphate of copper, 8 millims. thick-

ness of solution, opaque to rays less re

frangible than line F. Ditto, stronger solution, opaque below G.




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oscillation to and fro, showed that the first half, or the or consisting of polished metal) of the body on which maximum deviation produced, whilst under the influence radiation falls materially influence the movements. of radiation, occupied about the same time as the second 109. The accompanying, table gives the results of half, or the return swing, when the source of radiation numerous experiments as to the effect of screens, tried was cut off. The following are the observations. The with an exceedingly delicate apparatus, constructed as source of radiation was a candle, the intensity of action above desribed, the window, c' (fig. 7), being of quartz. being moderated by filtering the rays through glass The candle used was the kind employed. in gas photo.

metry, and defined by Act of Parliament as a sperm Half Oscillation, Whole Oscillation,

candle of 6 to the pound, burning at the rate of 120 grs. per under Influence of Radiation being cut off

hour.” The distances were taken from the front surface Radiation.

during the return swing. of the pith when the luminous index stood at zero. They 8:00 seconds. 15'00 seconds.

were in the proportion of 1 to 2 (140 to 280 millims.) to 750 15.00

enable me to see if the action would follow the law of 7.50 14'50

inverse squares and be four times as great at the half 7:50 15.50

distance. No such proportion can, however, be seen in 7:50 14:50

the results, the radiant source possibly being too close to 7'25 15'00

allow the rays to fall as is from a point. The figures 7:50 15:00

given are the means of a great many fairly concordant 7:50 15'00

observations. Where a dash rule is put I have tried no 7:00 14'00

experiment. The cipher oo shows that experiments were

actually tried but with no result.

The sensitiveness of my apparatus to heat-rays appears

to be greater than that of any ordinary thermopile and 7:25 15.00

galvanometer. Thus I can detect no current in the ther. 7:00 14'00

mopile when obscure rays from copper at 100° C. fall on 7'00 13:25

it through glass; and Melloni gives a similar result. 8:00

16:00 8:00 16:00

(To be continued). 7:50

15:00 7'00

15:00 8:00 15'00


TARTRATE.*. 7:50



(Concluded from p.233.)


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Mean., 14'77

If we should be in entire ignorance of the quantity of

potassium in a compound to analyse, we should take a The average time of the first half oscillation is there large quantity of tartaric acid, not more, however, than fore 7*47 seconds,* and of the second half 7'3 seconds. three times as much as the quantity of material weighed This small difference is not unlikely to be due to errors of for analysis, as the monosulphide, which is the compound observation.

having the greatest percentage of potassium, has 71 per After a long series of experiments the zero gradually cent, which, multiplied by 4, gives 2.84. The next in creeps up, showing that one side of the apparatus is order, potassic hydrate, has nearly, but not quite, 70 per becoming warmed. The conducting power for heat and cent. condition of the surface (whether coated with lampblack To return to the 10 c.c. of decinormal solution, we may

note that they contain 47 centigrms. of potassa, corres* By referring to paragraphs 106 and 107 it will be seen that I have put the time of the first halt oscillation as it'5 seconds. This was with another apparatus, having a glass thread of different torsion.

* Read before the American Chemical Society, September 7, 1876.


CHEMICAL SYEWS,} Estimation of Potassium as Acid Tartrate.
Dec. 8, 1876.

243 ponding to 39 centigrms. of potassium. We may then, After doing this, if we add as before 2 grms. of tartaric weigh approximately 2 grms. Of tartaric acid, which is a acid dissolved in water, a very slight precipitate will be little less than six times the quantity of potassium to be obtained, even after standing for hours, and however much precipitated. This acid is dissolved, and added to our the liquid may be stirred, or whatever quantity of alcohol 10 c.c. of decinormal solution. The liquid should now be we may add, the precipitate does not increase perceptibly. stirred sufficiently to make a thorough mixture of the If, instead of stopping at neutrality, a sufficient excess of solutions of potassa and tartaric acid. The crystals begin sulphuric acid is added, tartaric acid will not show the to deposit almost immediately, and the deposition in. least turbidity after continued agitation and addition of creases for about five or six minutes, when it stops, and large quantities of alcohol. Hydrochloric acid in the the liquid clears up. Alcohol should now be added to in- same circumstances behaves exactly in the same manner, crease the precipitate. This addition, however, requires as is also the case with nitric and phosphoric acids. From a few words of explanation.

the behaviour of potassic bromide and iodide, when in As the result of numerous estimations of potassium in presence of an excess of tartaric acid, we must conclude compounds of various kinds, I have found it advantageous that hydrobromic and hydroiodic acids belong to the same to add, at first, only a small quantity of alcohol, a volume category. about one-tenth of the liquid in the beaker-glass. After With all these acids, a quantity sufficient for neutralithis addition the liquid should be stirred sufficiently to sation of the potassa gives a slight precipitate, while an effect a thorough mixture, and then be allowed to rest excess prevents precipitation. In the first case, the prefive or six minutes, when the liquid above the precipitate cipitate produced can only take place by liberating a becomes clear once more. Finally, the rest of the alcohol quantity of the acid in combination, and after a sufficient should be added, a quantity sufficient to make the whole quantity of free acid has been formed further deposition is liquid in the beaker-glass contain at least 60 per cent of prevented. alcohol in volume. The liquid in the beaker should be The acids experimented on were powerful mineral acids, stirred up once more, and after becoming clear it should whose affinities for potassium are so great that, although be thrown on a filter.

the acid tartrate is more insoluble than any of their To ensure in an easy manner a quantity of alcohol equal potassic compounds, they only yield a small portion of to 60 per cent of the total volume of liquid, I mark on the potassium to tartaric acid. If, therefore, a weaker acid side of a beaker-glass a line corresponding to 50 c.c., which than the tartaric was chosen to combine with potassium, is easily done with a file, previously moistened with petro- it would not prevent the production of an abundant deposit leum or spirits of turpentine to prevent the abrasion from of acid tartrate. Acetic acid naturally suggested itself, cracking ihe glass. 50 c.c. are quite sufficient when we and, on being tried, was found incapable of preventing take i grm. of material for analysis. The volume of the this precipitation. Here, then, was our way out of the beaker-glass should be at least 200 c.c. This volume of difficulty. 50 c.c. is for the solution in water before adding alcohol. Before describing the manner in which this property of

In the case we have on hand, we have dropped 10 c.c. acetic acid was utilised, we must, for the better under. of decinormal solution of potassa in a glass, and added a standing of the subject, state that salts of sodium in a solution of tartaric acid. We may now add water up to solution containing 60 per cent of alcohol do not prevent the mark indicatir.g 50 c.c.

the precipitation of cream of tartar. The sulphate, the On the other hand, we have strong alcohol-say, of nitrate, the chloride, iudide, and bromide, the tartrate, and 931 per cent—which is the strongest common alcohol acetate seem equally powerless to prevent the formation found in the market, and which is sold under the name of of the precipitate. This is an important point, as by 95 per cent alcohol. I have no intention of giving rules means of soda or its carbonate we may separate the bases for mixtures of alcohol and water, which are familiar to that accompany potassium and ammonia, whose acid tarmost chemisis. In this case I will call your attention to trate is very insoluble, and may in presence of soda be this--that if you add 100 c.c. of 935 per cent alcohol to the driven off by heat. 50 c.c. of liquid in the beaker-glass, the result will be The property that acetic acid posseses, of allowing the 150 c.c., and if we divide 931 by 150 the result, 62-3, will complete deposition of cream of tartar to take place, sug: be the strength of alcohol required.

gusted at first the following process :-Given a compound After adding about 10 c.c. of strong alcohol to the 50 c.c. containing potassium, phosphoric acid, if present, would of solution in our beaker-glass, we finally add the rest of be separated as ammonio-magnesic, as tricalcic, or in any the 100 c.c. After the deposition of crystals has stopped, other convenient phosphate. The volatile acids could be the contents of the beaker are thrown on a filter." The driven off by excess of sulphuric acid and heat until fumes liquid that filters through gives a distinct red colour to of sulphuric acid began to appear. Sulphuric acid could . litmus paper. The precipitate on the filter should now be afterwards be precipitated with acetate of barium, thus washed with alcohol of 60 per cent until the filtered liquid leaving acetic acid as the only acid in the solution, in ceases to show a red colour with litmus paper. The pre- combination with all the bases. cipitate after this is ready to be washed down into a This process is simple in theory, but long, and altogether beaker-glass to be tested with potassa, aiter the liquid in detestable in practice. An analysis was already begun the glass has been sufficiently heated and coloured with on this plan, when another, much more simple and conlitmus. The glass containing cream of tartar in water is venient, suggested itself, which gave on trial the most placed under a burette, and, if the operation has been satisfactory results. This process consists in adding to carefully conducted, it will take exacly 10 c.c. of the the compound to be analysed, if it contains a strong decinormal potassa solution to turn the liquid in the beaker- mineral acid, a certain quantity of acetate of sodium and, glass from red to blue.

afterwards, tartaric acid. The effect of adding acetate of The condition of a solution containing only potassa and sodium is that if a strong mineral acid is in excess it forms water is one that very rarely, if ever, presents itself in a sodium salt by acting on the acetate, and liberates a chemical analysis, and we have in the next place to ascer- corresponding quantity of acetic acid. When tartaric acid tain the influence of bodies which are usually found in is afterwards added, and a quantity of acid tartrate is precipicombination, or in a state of mixture, with potassium. tated, the strong mineral acid set free reacts on the acetate,

If we drop 10 c.c. of a decinormal solution of potassa and acetic acid is again liberated. This action goes on in a glass, and add a few drops of solution of litmus, we until all the potassium has been precipitated as acid tarwill be able to find the quantity of sulphuric acid, added trate, and all the strong mineral acids originally combined drop by drop, which will neutralise the 10 c.c of potassa. with potassium have been combined with sodium, and a

* When soda is present in the solution it is expedient not to delay corresponding quantity of acetic acid has been set free. too much in throwing the precipitate on a filter to avoid errors in the

The quantity of acetate of sodium that I usually add is result. I propose in a future communication to examine this question. equal to the quantity of tartaric acid. The theoretical


CHEMICAL NEWS, 424 Estimation of Potassium as Acid Tartrate.

Dec. 8, 1876. quantity necessary is 55 per cent of the quantity of tartaric, but another part, although converted into cream of tartar, acid, but I always obtain excellent results by using equal will remain in solution. If the precipitate is thrown on a quantities; the excess does no harm.

filter without the addition of alcohol, and if we free it This action of acetate of sodium, in promoting the pre- from excess of tartaric acid by washing with water, a furcipitation of cream of tartar, is one of importance in testing ther loss will take place. If, instead of using pure water for potassium qualitatively. In our chemical books we to dissolve the tartaric acid added to our 10 c.c. of potassa find directions for precipitating potassium from its com solution, and to wash the precipitate of acid tartrate left pounds by means of tartaric acid, as if it was a difficult on the filter, we use a liquid incapable of dissolving cream and delicate operation. An addition of acetate of sodium of tartar the loss would be very much reduced. This we in conjunction with tartaric acid, and a discreet use of can easily do by using a saturated solution of acid tar. alcohol, will give indications of potassium in a few minutes, trate. When the impurities on the filter have been reeven when present in small quantities.

moved by washing with this saturated solution, the last To give an example of analysis of potassium, let us portion of this solution may itself be removed by washing take a sample of chloride, and weigh i grm. This is dis- with a small quantity of alcohol of 60 per cent. solved, and 2 grms. of acetate of sodium are added and

There will then remain one cause of error, due to the dissolved. We now dissolve 2 grms. of tartaric acid, and water introduced with the 10 c.c. of titrated potassa soluadd them to the niixture of potassic chloride and acetate tion, which may, with sufficient approximation, be conof sodium. We note the total volume of liquid, and, after sidered as 10 c.c. of water. To estimate this quantity, we the deposition of acid tartrate has stopped, we add about must use the table of Chancel already given, and if we one-tenth as much of alcohol of 931 per cent, when a fur- suppose that the temperature of the liquid is 25° C., we ther deposition takes place. Afterwards, the remaining shall find that at that temperature 100 c.c. of water will quantity of strong alcohol is added, which must be such dissolve 67 centigrms. of acid tartrate, amd therefore that the total volume of alcohol is double that of the ori- 10 c.c. will dissolve 67 milligrms., corresponding to ginal aqueous solution. The precipitated cream of tartar 16% milligrms. of potassa, and consequently to o‘35 of obtained is tested, exactly as before, by a decinormal

I c.c. of decinormal solution. If we have operated with solution of potassa.

care, we will find that we can account for the original Instead of estimating the precipitate of acid tartrate 10 c.c. of potasss solution within one-tenth of a c.c. volumetrically, it may be dried at 100° C., and weighed. The results, however, are not nearly so accurate when The volumetric analysis is, however, preferable, apart from salts of sodium are mixed with the potassa solution, and its rapidity and convenience, because by the action of alco-there is always a deficiency in the acid tartrate precipi. hol some compounds, such as sulphates, may in certain tated. I found, however, that a small quantity of alcohol cases be precipitated, but as they have not an acid reaction will in great part overcome this difficulty, but by using too their presence would not interfere with the estimation by much alcohol, as much as 10 per cent, the results are a titrated alkaline solution.

too high. After a great many experiments, I have been led To enable me to verify the accuracy of the results ob- to adopt 3 per cent as the strength of alcohol that gives tained by this process of analysis, I have in all cases taken the best results. The quantities of acid tartrate dissolved a stated volume of titrated solution of pure potassa, and I by 3 per cent alcohol at various temperatures are as folhave added sulphuric, nitric, and hydrochloric acids, and lows:varying quantities of sodium salts. The potassa dissolved

100 c.c. of Water having to form a.titrated solution was Tromsdorff's potassa by

Temp. C.

3 per cent of Alcohol will

Dissolve Cream of Tartar. alcohol, containing no soda. The acids leave no residue

Grammes. by evaporation, and can therefore contain no potassium. By saturating 10 c.c. of potassa solution with sulphuric,


0-25 hydrochloric, and nitric acids, the following results were obtained. The numbers represent the c.c. of the same


0°37 potassa solution, which saturated the acid tartrate preci

0-45 pitated in each case :








This alcohol of 3 per cent, saturated with acid tartrate, In making these experiments it was of the utmost im- is used to dissolve the potassium compound weighed for portance that my solution of potassa should be pure, but, analysis, to dissolve tartaric acid and acetate of soda, to in commercial tests, it matters little whether the standard dilute our solutions, and wash our precipitates. As the alkaline solution be of potassa or soda, as both neutralise temperature of a laboratory need 'not vary during an cream of tartar.

operation, no error need result from the quantities of The process for the estimation of potassium which I cream of tartar which alcohol of 3 per cent will take up have described is not always advisable, as the strength of at different temperatures. alcohol required may in some cases interfere with the Let us take a low sugar-house product to test for potassa, results. When a great many tests are to be made, as hap- in the shape of a syrup of 42° B. Suppose we take too pens in a factory, and at the same time extreme accuracy grms. of this, the quantity of water in our weighed sample is not required, the expense attending the use of so much will be 20:6 grms." To this we add a quantity of alcohol alcohol may be worth consideration.

equal to 3 per cent, or 3'3 per cent of alcohol of 934 per For i grm. of substance weighed for analysis 100 c.c. cent, which is seven-tenths c.c. We may now dilute our of strong alcohol are required, besides about 50 c.c. more syrup of f42° B. with alcohol of 3 per cent until it is quite for washing the precipitate. Altogether

, we may calcu- thin, and add about 5 grms. of tartaric acid if the low prolate that the alcohol for every test costs about 10 cents. duct is from cane sugar, or about 20 grms. if a beet pro. In testing the low produ&s of sugar houses for potassium duct. We should also add about the same quantity of strong alcohol cannot be used, because they contain sub-acetate of sodium, and after allowing deposition to take stances which become adhesive and unmanageable in pre- place for about fifteen minutes, the precipitate may be sence of strong alcohol.

treated as we have seen in other cases. To explain the process that I have used in such cases, After the acid tartrate has been saturated by the titrated let me take once more 10 c.c. of titrated potassa solution potassa solution, we should add to the result obtained by in a beaker-glass, and add enough tartaric acid to precipi- the burette, the quantity of potassa corresponding to the tate the potassium. A certain portion will be deposited, acid tartrate dissolved by the 20'6 c.c. of water which

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35 40

every kind.

Dec. 8, 1876.
Development of the Chemical Arts.

245 accompany the

100 grms. of 42° syrup and the oʻ7 c.c. of Prospecting for Sulphur.—The existence of sulphu r alcohol added, which are equal to 21:3 c.c. of alcohol of underground may be almost always concluded from char3 per cent. If the temperature of the liquid at the time of acteristic indications on the surface. As such the briscale filtration is 30° C., we will find in the table I have given is especially regarded, and where it crops out to daylight that 100 c.c. of alcohol of 3 per cent will, at that tem- it is as a rule certain to lead to deposits of sulphur. The perature, dissolve 60 centigrms, of cream of tartar, and occurrence of siliceous limestone and of sulphur springs consequently 21:3 c.c. will dissolve 13 centigrms., which are regarded as favourable indications. The first opera. represent 324 milligrms. of potassa, which should be added tion consists in driving strongly sloping adits, known by to the result.

the native miners as buchi or scaloni. The latter name The process based on the use of weak alcohol, saturated refers to the circumstance that they are laid out in stairwith cream of tartar, is of older date than the process I like flights, which are distinguished as sani and rotti first described. The results obtained are not uniformly according as they run on in a right line, or turn off at an satisfactory, for, although they are generally good, some. angle. times there will be errors of 21 or 3 per cent, which cannot

(To be continued.)
be attributed to any cause that I could discover. These
discrepancies induced me to try the other process, in which
the solutions are made to contain 60 per cent of alcohol,
and this has always given satisfactory results.



Consulting Chemist to the Metropolitan Board of Works, &c.
DEVELOPMENT OF THE CHEMICAL ARTS From the remotest time burning sulphur has been em-

ployed to fumigate and purify infected air, and to destroy

fermentative and putrefactive action. There is no agent By Dr. A. W. HOFMANN.

mere powerful in its effects than this. Unlike chlorine, it . (Continued from p. 233.)

not only acts as a disinfectant or destroyer of disease

germs and of the results of putrefaction, but it is also a The Sulphur Industry of Sicily.

powerful preservative agent, and, like carbolic acid, is a By Dr. ANGELO BARBAGLIA.

preventive of chemical changes in dead organic matter of The true home of sulphur is Sicily, where the deposits extend over a great portion of the island bounded on the understood, its use is necessarily limited by the difficulty

Although the value of sulphurous acid is thoroughly south by the mountains Delle Madoni, and comprising which exists in the way of producing it in a form in which almost the whole of the provinces of Caltanisetta and it can be readily applied. The ordinary method of geneGirgenti as well as a part of Catania as far as Caltagirone, rating it by burning sulphur is cumbrous and very uncerRammacca, and Centuripe. Besides this there are isolated deposits at Lercara, in the province of Palermo, there are also many situations in which the process can

tain, owing to the difficulty of keeping up the combustion; and at Gibellino, in the province of Trapani. The number of sulphur mines scattered in the above-men- it is inconvenient and but little under control. The

not be carried on at all, and under the best circumstances tioned provinces is very considerable. According to a statistical conspectus for the year 1872 the number ex.

evolution of the gas from its solution in water is scarcely

more convenient, while it is much less effective; indeed, ceeded 250, with a total yearly production of 1,861,700 it may be said that there is no ready; convenient, and metric quintals, requiring an outlay of 2,472,935 lire.

easily controllable way of producing this valuable agent Annual yield in

in use at present; and this is the more remarkable when Province.

Metric Quintals.
Expenditure in

it is considered what a ready and simple means we really
Average of 1869, 1870, Italian Lire.
and 1871.

have at hand for this purpose. Caltanisetta 781,400 1,264,390

Most of the readers of The Lancet are no doubt familiar, Catania



at least theoretically, with the substance called bisulphide Girgenti 826,200

of carbon. This is a compound of one atom of carbon

763,645 Palermo



with two atoms of sulphur (CS2); it is a dense, mobile

liquid, heavier than water, and intensely inflammable, 1,861,700 2,472,935

burning in the air like spirit of wine. During combustion

the constituents of the bisulphide combine with the According to the recent and highly interesting investigations of the mining engineer, Mottura, published in acid gases; but as 100 parts contain, by weight, as much

oxygen of the air, producing sulphurous and carbonic 1871, Sicilian sulphur is a product of the tertiary formation, and is found in the upper miocene between foliace parts of sulphurous acid, it will be seen that the volume

as 84 parts of sulphur, which will give, in burning, 168 ous crystalline gypsum and massive limestone (calcinari); of this gas from a given quantity of bisulphide greatly exits associates are bituminous marl (tufi) and gypsum. ceeds that of the carbonic acid, and is comparatively very The sulphuriserous deposits (veins, courses, beds) vary large. Suppose the above quantities to be in grains: as exceedingly in inclination, thickness, extent, and in rich- 100 cubic inches of sulphurous acid weigh 68.5 grs., the

In these deposits and on their outer boundary, 168 grs. will measure upwards of 245 cubic inches, or there is invariably found a granular, friable, whitish rock about one-seventh of a cubic foot, which is the volume of consisting chiefly of gypsum. The miners of the island sulphurous acid obtainable from 100 grs. of bisulphide. name this rock briscale, and suppose that from the purity

The bisulphide of carbon can be burned in a common and thickness which it displays on the surface they can spirit lamp, and in that case the products are sulphurous infer the richness and extent of the sulphur deposits. acid and carbonic acid only, in relative proportion to the The ores are divided into three groups

atomic composition of the bisulphide, as I have stated; Real Percentage. Yield.

but by a modification of the method of burning, the I. Richest


amount of sulphurous acid produced in a given time can 2. Rich


be regulated to any desired extent.
3. Ordinary


It is a property of the bisulphide of carbon to dissolve * Berichte über die Entwickelung der Chemischen Industrie in fat oils and hydrocarbon liquids, such as petroleum ; Während des Letzten Jahrzehends."

so by mixing it with any one of these liquids and burning





CHEMICAL NEWS, Protection of Buildings from Lightning.

Dec. 8, 1876. the mixture in a properly constructed oil or petroleum, that a series of solar photographs—taken regularly at in - lamp, sulphurous acid will be generated with the other tervals of about two hours, at a number of places on the usual products of the combustion of such materials, and earth's surface-would enable us to determine this quesin proportion to the quantity of bisulphide present in the tion which is now agitating the scientific world, since any mixture of combustible liquids; any proportionate quan. spots which crossed the sun's disk would be at once registity of sulphurous acid can in this way be thrown into an tered. As it is necessary that such observations be made atmosphere, and the action may be continued for any at several places and in several countries, M. Janssen length of time.

hopes that other countries besides France will ere long As the sulphurous gas is generated pari passu during arrange to have such a series of observations taken, and the combustion of the bisulphide, it diffuses itself in the he considers that in a few years the circumsolar regions air, which in a short time will become completely im- would thus be explored with a certainty which could not pregnated with it. In a room containing about 1300 cubic possibly be attained by any other method. He exhibited feet of air it was found that by burning 280 grs. of the some of the original photographs taken in Japan of the bisulphide the atmosphere was so far charged with sul. transit of Venus, and explained the advantage of placing phurous acid that it was impossible to remain in the room a grating in the focus of the camera in order to eliminate for more than a few seconds. In five minutes after the distortion. lamp was lighted litmus paper began to be reddened at Mr. Crookes showed the spectrum of a small specimen some distance from it ; in ten minutes the air had become of chloride of gallium which he had received from its very oppressive, and the litmus paper was reddened in the discoverer, M. Lecoq de Boisbaudran. The discovery extreme corners of the room; in fifteen minutes the air of this metal is of peculiar interest, as M. Mendeleef had was so charged with the gas that it could scarcely be previously, from theoretical considerations, asserted it to breathed, and in twenty minutes it was unbearable.' In exist, and had also correctly given some of its chemical that time, as I have said, 280 grs. of bisulphide were con- and physical properties. The most prominent line in the sumed in a simple single-wick lamp.

spectrum was a bright line in the blue, somewhat more Sulphurous acid generated in this manner can be refrangible than that of indium. applied with facility to the disinfection of any place or Mr. Lodge briefly described a model he has de. object. In the case of rooms in which infectious or con- signed to illustrate flow of electricity, &c., which is fully agious disease has prevailed, it is only necessary to light explained in a paper in the Philosophical Magazine for the lamp and allow it to burn until the atmosphere has November, and he showed how similar considerations can become impregnated with the gas to any desired extent, be applied in the case of thermo-electric currents. The and then to remove or extinguish it just like a common model in its simplest form consists of an endless cord spirit lamp. In the simple form of apparatus which I passing over four pulleys, and on one side of the square suggest for this purpose, the lamp is enclosed in a metal | thus formed it passes through a series of buttons held in case, about 3 inches in diameter and 8 or 9 inches high, their positions by rigid rods or elastic strings, according furnished with holes near the bottom for the admission of as they represent layers of a conducting or non-conducting air, and others in the top for the emission of the sulphur- substance. When considered in connection with thermoous gas.

This can be conveniently moved about, and electricity the buttons are assumed to oscillate on the placed, while the lamp is burning, in almost any locality. cord, and if they move in one direction with greater veloReceptacles for infected clothing, or the clothes or linen city than in the other, the cord will tend to move in the used in connection with disease, or carriages which have former direction. Now, at a junction of copper and conveyed fever or other patients, can we thoroughly iron, since the metals have different atomic weights and purified without difficulty and with very little trouble. their kinetic energies are equal, the velocities must differ For the disinfection of ships, too, the lamp is particularly on each side of the junction, and an unsymmetrical oscillasuitable, as it can be carried into the remotest part of a tion of the molecules must ensue, analogous to that ship and burned without the least danger, and with the assumed by Mr. Stoney to take place in Crookes's radio. certainty of effecting its object completely.

meter, and the cord, or electric current, will advance when It must be observed that the bisulphide of carbon is ex- two junctions are at different temperatures. Mr. Lodge tremely volatile, having its boiling-point as low as 110° F.; showed experimentally that for a given difference of temt is therefore necessary that the lamp in which it is perature the maximum thermo-electric current is obtained burned should be furnished with a well-fitting screw-cap, when one of the junctions is at 280° C., and beyond this to prevent the liquid from evaporating, and at the same point the amount of deflection decreases. This fact led time to keep its peculiar odour from escaping. This Sir W. Thomson to discover the convection of heat by odour is often very nauseous, but the bisulphide is now electricity; that is, if we have a circuit composed of manufactured by Messrs. C. Price and Co., of Thames copper and iron, and one of the junctions is at the Street, so pure, that it possesses very little smell, and above temperature, the current, in passing from hot to can be used without the least inconvenience.-The Lancet. cold in the iron or from cold to hot in the copper, absorbs Printing-House Square.

heat. This fact was experimentally illustrated by Mr. Lodge. A strip of tin plate is symmetrically bent so as to nearly touch the two faces of a thermopile, and is heated at

the bend by steam passing through a brass tube on one side PROCEEDINGS OF SOCIETIES. (not end) of the thermopile, and kept cold by a current of

water on the other side. As the arrangement is symmePHYSICAL SOCIETY.

trical no current is found to pass through the thermopile,

but when a powerful voltaic current passes through the November 2nd, 1876.

strip of metal a reversible deflection of the needle is ob

served, in accordance with the above law. Professor G. C. Foster, F.R.S., President, in the Chair.

MANCHESTER LITERARY AND PHILOSOPHICAL The following candidate was elected a member of the

SOCIETY. Society :-G. Waldemar von Tunzelmann.

Ordinary Meeting, October 17, 1876. M. JANSSEN made a brief communication, in French, with reference to a method which he has proposed to the E. W. BINNEY, F.R.S., F.G.S., President, in the Chair. Académie des Sciences for ascertaining whether planets really exist between Mercury and the Sun. After men- MR. BAXENDELL drew attention to a paper, “On the Protioning the importance of photography from an astrono- tection of Buildings from Lightning,” read by Prof. J. mical point of view, he explained his reasons for hoping Clerk Maxwell at the late meeting of the British Associa

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