659. The singular effects of retardation produced by very small quantities of some gases, and not by large quantities of others (640. 645. 652.), if dependent upon any relation of the added gas to the surface of the solid, will then probably be found immediately connected with the curious phenomena which are presented by different gases when passing through narrow tubes at low pressures, which I observed many years ago[A]; and this action of surfaces must, I think, influence the highly interesting phenomena of the diffusion of gases, at least in the form in which it has been experimented upon by Mr. Graham in 1829 and 1831[B], and also by Dr. Mitchell of Philadelphia[C] in 1830. It seems very probable that if such a substance as spongy platina were used, another law for the diffusion of gases under the circumstances would come out than that obtained by the use of plaster of Paris. [A] Quarterly Journal of Science, 1819, vol. vii. p. 106. [B] Quarterly Journal of Science, vol. xxviii. p. 74, and Edinburgh Transactions, 1831. [C] Journal of the Royal Institution for 1831, p. 101. 660. I intended to have followed this section by one on the secondary piles of Ritter, and the peculiar properties of the poles of the pile, or of metals through which electricity has passed, which have been observed by Ritter, Van Marum, Yelin, De la Rive, Marianini, Berzelius, and others. It appears to me that all these phenomena bear a satisfactory explanation on known principles, connected with the investigation just terminated, and do not require the assumption of any new state or new property. But as the experiments advanced, especially those of Marianini, require very careful repetition and examination, the necessity of pursuing the subject of electro-chemical decomposition obliges me for a time to defer the researches to which I have just referred. _Royal Institution, November 30, 1833._ SEVENTH SERIES. S 11. _On Electro-chemical Decomposition, continued._[A] P iv. _On some general conditions of Electro-decomposition._ P v. _On a new Measurer of Volta-electricity._ P vi. _On the primary or secondary character of bodies evolved in Electro-decomposition._ P vii. _On the definite nature and extent of Electro-chemical Decompositions._ S 13. _On the absolute quantity of Electricity associated with the particles or atoms of Matter._ [A] Refer to the note after 1047, Series VIII.--_Dec. 1838._ Received January 9,--Read January 23, February 6 and 13, 1834. _Preliminary._