On a 2Vew .~trrangement of the Voltaic Couple. 141

practically economical, for the salts which compose it are of but little value, and as it conducts electricity very well, it requires much less than the alkahne baths.--Coml)les Rendus de l Jtcadem,e des Sczences, ( Par~s,) 12th ~qt~ril, 1852.

Translated for the J ~urnal of the Franklin Institute.

.3 New .~rra~g'emenl of the Voltaic Couple. .Note ofS'I. FAnJaE DE LA Gmt~cE, prese~led by M. BECqUEI~D.

I have discovered a method of making the current of the voltaic pile, perfectly constant and invariable, even for weeks and months, of whatso- ever metals the electrodes may be tbrmed; whether they be put into action by separate liquids, as in the combination of Bunsen, or by a single liquid, as in the arrangement of Volta.

This continuousness of the electric action is obtained, as is that of the l~eat o[' a thrnace provided below with a grate to let the cinders lhll~ and eontimtally supplied with combustible from above.

The means which I employ is simple, and fiflfils all the conditions which can render it applicable in practice. In place of increasing the expense, it diminishes it.

Let us look tirst at the arrangement of a single couple with a single liquid. Let there be a vessel having a hole pierced in the middle of its botto,u; in this vessel, let there be a concentric diaphragm of sail-cloth, rising not so high as the edge of the vessel, and fixed by cement to the bottom. Withia the diaphragm is a cylinder of' very dense gas-coke, surrounded by small pieces of the same material, and around the diaphragm a cylinder of amalgamated zinc, and acidulated water, which is supplied drop by drop fi'om above.

Let us now join the poles by a conducting wire, and let us see what ]~asses in the inside of' the apparatus. The acidulated water which con- linues to come drop by drop from above, will pass over the top of the cloth diaphragm upon the charcoal: which will be thus continually washed hy the movement of the liquid, without, however, being soaked, so that the polarization will be suspended, and the bubbles of hydrogen -a, ill disengage themselves freely from lhe inte,'stices of the grams; on the ether hand, the lower layers of acidulated water will, fi'om the effect of tl~c pressure which they support, filter slowly through the cloth, xvhieh the llpper an d middle layers will not do in any perceptilfle degree. Now these lower layers arc precisely those xvhieh contain the sulphate of zinc which is to be eliminated. The result is an electric current, which is enti,'ely constant untit the zinc has entirely disappeared, and is obtained with- out other care than that of supplying the reservoir.

The tbllowing is the method in which I unite a large number of couples: the stoneware cups which contain them, being three or four diameters in length, and consequently resembling tubes, are united and cemented into a bundle or block easily carried. The upper surface is horizontal, small gutters lead the acidulated water to each cup. \Vilh this disposition, by placing a second reservoir over the pile, and ehanging the nature and

142 .~Iechaaics, Ph~jsics, and Chemls&y.

height of the diaphragms, it is easy to employ a second liquid, which is dropped directly, and drop by drop on the carbon; as tbr instane% nitric acid. It is used advantageously very weak, and when it can no longer serve for the Bunsen battery, because it no longer absorbs hydrogen.

'l'he liquids, as they came nit" front the cups, are col!coted, m~d may serve again until they are satu,ated.

Oa [he Decolorizb~g Propecljt ?f (J/~clrco~d aml several olher }~o'J'ies, By E. [,hmum.*

It is gcl~erally s~',m~d flint e,h,:n'coa! is the only simp]e body which pos- sesses the property ~/ absorbil~g coloring malter dissolved in a liquid; it f'Jrlher appears from the inve:~tigalions of ~M. I~ussy and 1)~0'e% that dceoloratim, by charcoal is a purely physical phenomenon.

Several compound bodies (alumina, sulphale of lead pi'epared by the moist way, hydrate of lead,) also pmt:dc.., of the property of decolonizing liquids; but it is generally considered by chemists dmt the action exerted !or.. oxides on coloring matter in the. preparation of lukes, is chemic:al, dilIiMng in this respect from that of charcoal; imverthclcss, ]3erzetius was of opinion that the deeoloralion efibcted by the oxides and metaltie salts resembled that produced by charcoal. My ot~ject has been to l ) r { i v e : -

]. That charcoal is not the only shnpIe body possessing the property i of r!ee(dorizing liquids; sulphur, arsenic, and iron, obtained by the reduc-

tion of the hydrated sesquioxide by hydrogen, are all possessed of deeo- loriziug power.

52. That lhe number of compound bodies having an appreeia]~le deeo- lorizing power, are more numerous than has been thought, and that ~his power appears to depend much more on the state of division of these bodies than on their chemical properties.

3. That such bodies which easily appropriate one coloring matter mar have but little tendency to do so with another; thus phosphate of l ime Ii'om bones (artificially obtained) scarcely decolorizes the sulphindigotate of" soda, whilst it exercises a more energetic influence on tinctu,'e of litmus titan does animal charcoal.

3. That the deceleration, in the majority of cases, is a purely physical l~henomenon; thus the same coloring matter is absorbed by melalloids, melals, acids, bases, salts, and organic substances. It is easy, moreover, lw employing suitable solvents, to remove the coloring matter in an till-- altered state from the body which had absorbed il.

[ do not doubt but lhat these facts may prove useful in analytical che- mistry and in some manut\~cluring processes.

The following" resuhs, which [ have extracted from my memoir, will give some idea of the energ'y with which eerlain deeolorizing matters act.

'~ From lhe London Chemical Gazette~ April, 1852.