^{page 110 note *} On the action of voltaic electricity on alcohol, ether, and aqueous solutions. Edinburgh Transactions, vol. xiii. Part II.

^{page 110 note †} Bib. Univer. xxiv. 128.

^{page 111 note *} Transactions of the Royal Society of Edinburgh, vol. xi. p. 15.

^{page 111 note †} See Inorganic Chemistry, vol. ii. p. 295.

^{page 111 note ‡} The specific gravity of absolute Pyroxylic spirit is given by MM. Dumas and Peligot as .798 at 68° F., and its boiling point 151.7° F. at 30 inches of the barometer. In the case of alcohol, the difference of temperature at which the specific gravity was taken by the French chemists and myself, would very nearly account for the difference of specific gravity, and I did not conceive it of any moment to attempt to rectify the pyroxylic spirit more highly, because in regard to alcohol I had found that far greater differences in the density had no material influence on the voltaic results; and the analogy of the action on the two fluids was complete, as will soon appear.

^{page 112 note *} See fig. 2 of plate in former memoir. Ed. Trans, xiii. pl. xiii.

^{page 113 note *} All the batteries employed in the experiments in this paper were, as formerly, on Cruickshanks' construction.

^{page 114 note *} If any one should imagine that the water of the hydrate of potash employed has any effect on these experiments, he is at liberty to calculate the quantity of water in part of potash, held in solution by a few drops of spirit contained in a watch-glass. Again, the quantity of spirit acted on in the experiment in the preceding page, contained .16 of agrain of hydrate of potash, which contains .03 of water, equivalent to .154 of a cubic inch of hydrogen. But above two cubic inches of hydrogen were collected, and the process was stopped while the evolution was going on. Similar observations apply to the experiments with alcohol. The true action of the potash in these cases is just the same as when it is dissolved in water itself. It increases the conducting power of the liquid, aided, in the case of alcohol and pyroxylic spirit, by a circumstance to be noticed immediately.

^{page 116 note *} Even should we assume that pyroxylic ether and sulphuric ether unite with acids after the manner of bases, this circumstance will not, I conceive, prove them to be oxides, consisting of radicles as such and oxygen, any more than the same circumstance proves the vegetable alkalies, although undoubtedly bases, to be oxides, or than the circumstance that the vegetable acids unite with alkalies, shews that they consist of radicles and of oxygen.

^{page 117 note *} Edinr. Trans, xiii, 339, et seq.

^{page 119 note *} Annales de Chim. et de Phys. xxviii. p. 160.

^{page 120 note *} I am quite aware that when both the poles are introduced directly into the mixed solution, the voltaic power being in fresh action, there is effervescence at both poles, along with the appearance of iodine at the negative; but in this case I apprehend that a part, although not the whole, of the hydrogen enters into the new combination.

^{page 121 note *} When this transparent substance was heated, it gave off moisture, so that it appeared either to be a hydrate or an alcoate of magnesia, but the experiment had afforded too little to determine this point.

^{page 122 note *} It would appear that Döbereiner had observed the formation of resinous matter in small quantities, in a galvanized solution of potash in alcohol (Pog. Annal. xxiv. 609), but he says nothing of any evolution of elastic fluid at either pole; and although he regarded the formation of resinous matter as an effect of oxidation, he gives no more explicit opinion as to the source of the oxygen or nature of the action. On the other hand, M. Lüdersdorf (Ib. xix. 77), like Dr Ritchie, had observed that absolute alcohol, holding nothing in solution, gave off, under strong voltaic agency, elastic fluid from the negative pole; but he did not state that it was hydrogen, and, on the contrary, seems to have thought that it was not hydrogen, from the colour of its flame. I have found that the hydrogen evolved from pyroxylic spirit under electric action, when it contained a little of the vapour of the spirit mixed with it, burned with a blue flame, but when freed from that vapour, by being washed with solution of potash, it burned with a pale whitish flame. In analyzing, by the voltaic eudiometer, the gases obtained in such experiments, deceptive appearances, if we are not on our guard, may arise from the production of small quantities of carbonic acid, proceeding from the presence of vapour of the spirit which has passed over. I had read both Döbereiner's and Lüdersdorf's observations, when first published, but in the two or three intervening years they had escaped my memory, until again recalled to it by allusions to them which I met with in the course of my reading, subsequent to the publication of my former paper; and even if I had remembered them at an earlier period, they could not have superseded any part of my researches.

^{page 122 note †} Edinb. Trans, xiii. 327, et seq.

^{page 124 note *} It was necessary from time to time to add a little alcohol to the negative liquid, to prevent its level getting too low, an observation which applies to all the subsequently detailed experiments with alcoholic solutions.

^{page 128 note *} An. Ch. et Phy. xliv. 271.

^{page 128 note †} Jahrsbericht, xi. 56.

^{page 128 note ‡} An. de Ch. et Phy. xlv. 324.

^{page 128 note} Jahrsbericht, xi. 57.

^{page 134 note *} It will be readily understood, that when the poles are actually in the solution, the acid should first appear at the positive pole, and thence spread into the liquid when it has accumulated, as was shewn by M. De La Rive; but when the poles are beyond the solution, the acid must make its way from the solution to the pole through the interposed water, and unless carried through the water as fast as it is produced, it must accumulate in the solution.

^{page 134 note †} Pog. Annal. xxxix. 134.

^{page 134 note ‡} Experimental Researches, seventh series.

^{page 135 note *} P. 7, et seq.

^{page 135 note †} P. 10.

^{page 135 note ‡} Edinburgh Transactions, vol. xiii. p. 331.