ON PYROXYLIC SPIRIT, &c. 113 



tic fluid, to the action of seventy-two pairs of 4-inch plates.* In a few minutes 

 elastic fluid began to be evolved, and was collected over mercury ; and the liquid 

 after a time became ^varm, but did not boil. In order to favour the action, the 

 foils were only about j^oth of an inch apart ; which circumstance made it difficult 

 to say with certainty, from the appearance alone, from which pole the gas came ; 

 but from the nature of the elastic fluid, as afterwards determined, as well as from 

 the subsequent experiments, and the analogy of alcohol, little doubt could exist 

 that it proceeded from the negative foil. After one and a-half hour's action, 

 about one-third of a cubic inch was obtained, and, from the diminished action of 

 the battery, the flow was a good deal slackened. This gas was analyzed in the 

 voltaic eudiometer, and was found, as in the case of alcohol, to be hydrogen 

 mixed with a little impurity, which was partly common air or its constituents, 

 and partly a trace of vapour of the liquid acted on. 



The pyroxylic spirit which had been acted on, when mixed with water and 

 evaporated, shewed a little whitish matter mixed with it, and afforded a peculiar 

 smell ; and when the evaporation was carried to dryness, some yellowish- white 

 resinous matter was left. 



A minute quantity of pure caustic potash, when dissolved in the liquid, had, 

 as in the case of alcohol, a wonderful effect in promoting the voltaic action. A 

 similar quantity of the spirit, as in the last experiment, containing in solu- 

 tion 5 Jo of pure caustic potash, was acted on in the same apparatus by thirty- 

 six pairs of 4-incli plates, the platinum foil poles being parallel to one another, 

 and from one-eighth to one-tenth of an inch apart. Elastic fluid was immediately 

 evolved, and from the greater distance of the foils it was easy to see that it pro- 

 ceeded entirely from the negative pole. The action was so intense that the liquid 

 soon boiled. A cubic inch of permanently elastic fluid was collected over mercury 

 in a quarter of an hour ; and when two cubic inches had been obtained, the pro- 

 cess Avas stopped, although gas was stiU coming over. A portion of this gas was 

 analyzed as before, and found to be hydrogen in a state of nearly perfect purity. 



The liquid during the action did not perceptibly change in colour. A little 

 flocky matter had precipitated, but it did not appear to be carbonate of potash. 

 Some of the liquid was mixed with water, and after being a good deal concentra- 

 ted by heat, it became slightly muddy, and a pungent aromatic smell arose, and 

 some brownish matter was left on evaporating to dryness. 



When a little of the spirit containing about ^oo of potash was acted on in a 

 watch-glass by fifty pairs of 2-inch plates, the platinum-foil poles being simply 

 approached to one another horizontally, elastic fluid was evolved, as in the pre- 

 ceding experiment, from the negative pole, and none from the positive foil ; but 



* All the batteries employed in the experiments in this paper were, as formerly, on Cruickshanks' 

 construction. 



VOL. XIV. PART I. P 



