The heat raised by oxygen gas, when projected through a blow-pipe upon a piece of burning char coal, excites the greatest heat that is known. Some very interesting experiments upon this subject were made at the London Philosophical Society.in 1798, and arc detailed in the Philosophical Magazine, vol. viii. The nose pipes, which were used in these ex periments, are shewn in Fig. 10. The socket A re- / ceives a pipe coming from the gasometer, which con- r tains the gas. Upon this pipe are two brass boxes d and e, into which are fitted the tubes f, g, which turn in these boxes, air tight, for the purpose of en abling the operator to move the blow-pipes h, i nearer or farther from each other. The blowpipes ls, i also turn at k, 1, in the tubes f, g, to enable the ope rator to alter the direction of the streams, and make them fall on the charcoal 77T, at any angle he pleases. This apparatus may be adapted to fit on the end of the blow-pipe, Fig. 9. and may, with very little al .teration, be constructed to throw the flame of two lamps into one focus, as has been proposed by a gen tleman in America. An inconvenience sometimes occurs in using the inverted receiver : When the blowing stops, and the pressure of the water forces the air from the internal receiver, the momentum of the water rising upon it, is such as to dash up into the pipe, and put out the lamp. To prevent this, a Wire is
soldered to the bottom of the outside cistern, and ex tends upward through its whole height.. Upon this wire a cork slides, and always floats upon the sur face of•the water ; so that if it rises above its proper level, this cork rises, and forms a plug to close the ori fice in the top of the dome, and prevent the water from getting out. For farther information on blow-pipes, see Leblond, in Rozier's Journal, torn. xxx. p. 92. Haas, in Nicholson's Journal, 8vo. vol. iii. p. 119. Marquard, in the ItTertory of Arts, vol. xiii. p. 279. Hassenfratz, in Rover's Journal,' vol. xxviii. p. 345. Hooke, in Nicholson's Journal, 8vo. vol. iv. p. 100. and the same work, 8vo. vol. iii. p. 1. Sec also Dr Thomas Young's Natural Philosophy, vol. ii. p. 534, where the reader will find some curious observations made with the blow-pipe. (J. F.)