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Published online by Cambridge University Press: 17 January 2013
I was led into the following train of investigation from observing, that, when minute quantities of certain substances were dissolved in alcohol, and the liquid was acted on by a moderate voltaic power, evident signs of decomposition were exhibited by the evolution of elastic fluid at the negative pole. In investigating the nature of the changes produced, I was farther led to examine the action of voltaic electricity on a variety of alcoholic solutions, and also the agency of more powerful galvanic batteries on pure alcohol and on ether; and, ultimately, I was conducted into a field, into which I should have hesitated voluntarily to enter, namely, the voltaic decomposition of aqueous solutions, which has recently been investigated with so much success by a distinguished cultivator of science. In the following paper, it will be my object to give some account of the experiments which I have made on these different subjects, and of the results and views to which I have been led.
page 316 note * Phil. Trans. 1832.
page 320 note * All the galvanic batteries employed in the experiments detailed in this paper were fixed in mahogany troughs in the usual way. The charge employed was two measures of sulphuric acid, one measure of nitric acid, and about 100 measures of water.
page 321 note * I obtained the alcohol of this specific gravity by Mr Graham's process of exposing alcohol .830 to the vacuum of an air-pump with quicklime, the exposure being continued for some weeks, and the lime, which was common building quicklime, being renewed during the process. I could not get it of lower specific gravity. The specific gravity of .7928 at 66° F. appears, by Meissner's table, to correspond with .795 at 60° F., and with .792 at 68° F., or 20° C. In this country, absolute alcohol is usually reckoned to have a specific gravity of .796 at 60° F.; and on the Continent it is held to be of .791 at 20° C. Meissner, while he gives this latter as the specific gravity of absolute alcohol, states that the alcohol from grain, which is that used in this country, cannot be carried below .792 or .793.—Gmelin's Handbuch, ii. 276. The difference is in all probability due to the presence of a little of the volatile oil which grain and potato spirit contain.
page 323 note * New Edinb. Philos. Jour. April 1833, vol. xxviii. p. 231Google Scholar.
page 324 note * New Edinb. Philos. Jour. April 1833, vol. xxviii. p. 231Google Scholar.
page 324 note † Such a weak solution suffers no spontaneous change in the same time, even with contact of air.
page 325 note * Page 317–18
page 330 note * I compared the indications of this galvanometer with those of two astatic sewing needles, each two inches long, one of which was placed in the centre of a coil of twenty circuits, and found the indications of the long needle fully the more delicate.
page 331 note * This experiment was made with the long needle formerly mentioned. What might be the effect on a more delicate instrument I do not pretend to say.
page 333 note * Annales de Chim., tom. xcv.
page 333 note † Annales de Chim. et de Phys., tom. li. p. 313.
page 333 note ‡ Poggend. Annal. xxviii. 627.
page 333 note ∥ Annales de Chim. et de Phys., tom. lv. p. 132.
page 334 note * See Note, p.321.
page 337 note * It is only doing justice to MM. Gay Lussac and Thenard to remember, that they long ago employed the quantity of the gases evolved by water under the agency of the voltaic current as a measure of its chemical effects (Recherch. Phys. Chim., Part i.) They did not, however, compare this quantity with other effects produced by the same current at the same time.
page 339 note * Page 327
page 349 note * The attempts to show that it contains traces of a protoxide are evidently too imperfect to be entitled to regard, in their present state.
page 349 note † The iodic acid was prepared in the usual way by the agency of nitric acid, and was several times alternately dissolved in water and evaporated to dryness, to free it from nitric acid.