B L O W - P I P E. 



615 



Blow -pipe. 



w 



Hook's al. 



cohol 



blow-pipe, 



Plate 

 I.XII. 



ri ff . 8. 



New blow- 

 pipe by the 

 writer of 

 this article. 



Plate 

 I.XII. 

 Fig. 9. 



or vapour passing over through the syphon tube to 

 the flame at C. Its advantages are, steadiness of the 

 flame, and, at the same time, the inflammable vapour 

 very greatly increases the effect. The only objection 

 to it is, the expense of alcohol and the two lamps. 



Fig. 8. is another form of the same instrument, 

 proposed by Mr Benj. Hook. Here the boiler is a 

 globe B, supported in a ring fixed on two pillars aa. 

 Between these, a small lamp E slides up and down, 

 and is retained at any height, by the friction of two 

 small springs. This lamp at the same time heats the 

 boiler B, and its flame is urged by the vapour which 

 issues at a pipe F. This passes through the boiler, and 

 rises up above the surface of the spirit, so that there 

 is no danger of its boiling over into the tube. At 

 G is a valve, loaded with a weight acting as a safety 

 valve, to permit the escape of the vapour, if it should 

 become so strong as to endanger the rupture of the 

 vessel ; and at H is a screw plug, through which the 

 alcohol is introduced. This instrument acts in the 

 same manner as that before described ; and the ad- 

 justment of the distance of the wick from the jet is 

 affected in the same manner. The alcohol blow- 

 pipes are not a new invention, one being described 

 by the Abbe Nollet, in his Art des Experiences, 

 published in 1770. They have, however, but lately 

 been brought into use, and are found to answer ex- 

 tremely well for small experiments, where the con- 

 sumption of alcohol is not serious. 



From what we have already said, our readers will 

 form some idea of the requisites for a good blow- 

 pipe ; and we*beg to present them with one, con- 

 structed on the same plan as the great blowing en- 

 gines for the iron furnaces. It is represented in 

 Fig. 9. of Plate LXII. where AB is a vessel of ja- 

 panned tin, or glass, containing water, and C another 

 included within the former, and closed by a dome 

 at top, and open at the bottom. It is supported in 

 the other vessel by a ring or cover, soldered to both, 

 and perforated with several holes, as shewn in the 

 Figure. On the top of the dome, a short brass tube 

 is soldered, the outside of which is made conical, for 

 the reception of a socket, projecting from the side of 

 a common blow-pipe D. The mouth-piece of this 

 blow-pipe is made globular at ft, and a short tube b 

 is fitted into it, with a valve adapted to the end of it, 

 shutting outwards, so as to prevent the return of any 

 air into the mouth. At the other end of the blow- 

 pipe, a curved tube d is fitted on, which has the jet 

 at the end of it. The lamp E is situated on the top of 

 a pedestal, and can be raised or lowered at pleasure, 

 by means of the rivetted nut F. This nut fits upon 

 a screw formed on the stem of the lamp, the lower 

 part of which stem is made square, to prevent it turn- 

 ing round by the action of the nut. The vessel 

 makes a steady support for blow-pipes, which is 

 used by applying the mouth to the tube b, and 

 throwing air into the interior vessel C ; this expels 

 the water at the lower end of it into the external 

 vessel ; and the pressure of the water to return to its 

 original level, causes a constant compression of the 

 air, and forces it through the jet into the flame of the 

 lamp. By this means it is not necessary to blow 

 constantly with the mouth ; for if the air is forced 

 into the receiver at intervals, the pressure of the wa- 

 ter will expel it in a constant stream, and the opera- 



Platb 



tor will not be fatigued by any of the causes above 

 enumerated ; or he may take his mouth from the 

 pipe at any time for a few seconds, without interrupt- 

 ing the stream ; and he may take the air into his 

 mouth, and blow it into the tube, so as to supply it 

 with pure atmospheric air, instead of that which has 

 passed into the lungs: orifitis more convenient, he may 

 employ an assistant to blow. The socket which con- 

 nects the blow-pipe with the dome C, is made coni- 

 cal, and fits on very stiff, so as to fix the blow-pipe 

 very firm, at the same time that it admits the pipe to 

 have an angular motion. To adjust its distance from 

 the frame, the joint connecting the jet d with the pipe, 

 is fitted in the same manner, to admit of changing the 

 elevation of the jet ; and a jet of any other form oi 

 size may be fitted on at the same joint. It will easily 

 be seen, that this blow-pipe may be adapted to blow 

 with oxygen gas, by connecting a flexible tube with 

 the mouth piece b. The gas is injected into this pipe 

 from a bladder filled with gas, by means well known 

 to chemists. 



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 are 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- lxh. 

 tains the gas. Upon this pipe are two brass boxes Fig. 10. 

 d and e, into which are fitted the tubes^, 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 blow-pipes h, i 

 also turn at k, I, in the tubes f, g, to enable the ope- 

 rator to alter the direction of the streams, and make 

 them fall on the charcoal m, 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. 1 19. 

 Marquard, in the Repertory of Arts, vol. xiii. p. 279. 

 Hassenfratz, in Rozier's journal, vol. xxviii. p. 345. 

 Hooke, in Nicholson's Jour mI, 8vo. vol. iv. p. 100. 

 and the same work, 8vo. vol. iii. p. 1. See 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.) 



BLOWING, an operation by which a continued 

 stream of air is projected with great force and veloci- 



