198 Miscellanies. 



had ihe play of junction and separation commenced, before the de- 

 composing force of the platina poles was evident, in the form of two 

 columns of smoke, consisting of an infinite number of small gaseous 

 bubbles, which, uniting at the top of the receiver, yielded, in a short 

 time, a dose of oxygen and hydrogen sufficient to produce a sensi- 

 ble detonation. 



The phenomenon is still more interesting, when the development 

 of gas is viewed through a lens. The bubbles are more abundant, 

 as the motions of the electromotor are the more prompt. 



I shall not, at present, describe the results obtained from various 

 saline metallic solutions; the analogy between these effects and those 

 of hydro-electric currents appears to be complete, regard being had 

 to the intermission and fugacity of the one, and the continued action 

 of the other. 



It is not easy to foresee to what extent the means of exciting and 

 increasing the chemical power of the magneto-electro-motive faculty 

 may be carried ; but that a character so highly interesting to the doc- 

 trine of imponderable fluids ought to claim the attention of men of 

 science, is very certain. — Bib. Univ. Sept. 1832. 



3. A water barometer. — At the suggestion of J. F. Daniell, Esq. 

 professor of chemistry in Kings College, London, a water barometer 

 was ordered to be constructed under his direction by the president 

 and council of the Royal Society, and an account of its operation 

 was read by him to the society on the 21st of June last. The tube 

 was skilfully made by Pellatt &. Co., at the Falcon glass-house. It 

 was forty feet long and one inch in diameter, and so nearly cylindrical 

 throughout its whole extent as to diminish only two tenths of an inch 

 at the upper end. It was securely lodged in a square case, by means 

 of proper supports, and placed in the winding staircase leading to the 

 apartments of the Royal Society. A small thermometer, with a pla- 

 tina scale, was introduced into the upper end of the tube. An ex- 

 ternal collar of glass was united to that end, by heating it, to give it 

 additional support and prevent it from slipping. 



This end of the tube was then drawn out into a fine tube, ready 

 for sealing with the blowpipe, and a small stop cock was fitted to it. 

 The cistern of the barometer was formed by a small copper steam 

 boiler, eighteen inches long, eleven wide, and ten deep, capable of 

 being closed by a cock, and having at the bottom a small receptacle 

 for holding the lower end of the tube, so as to allow of the water in 



