BLOW-PI^E. 



613: 



the extreme point. The object to be heated is held 

 1 so that the flame strikes upon it ; or, if it is large, it 

 should be placed upon a piece of charcoal, which re- 

 verberates the flame forcibly on all sides of the ob- 

 iect, and at the same time'maintains the heat by its 

 own combustion. This" simple instrument is very ef- 

 fective in the hands of a dextrous operator ; but the 

 principal objection to it is, that, after using it a few 

 minutes, the moisture of the air blown from the lungs 

 is condensed, and accumulates in the tube till a drop 

 is formed, which, by means of the current of air, is 

 thrown so forcibly through the flame upon the ob- 

 ject to be heated, as to cool it, and spoil the expe- 

 riment. To remedy this defect, and render the in- 

 strument more convenient, many different forms have 

 been proposed. 



In consequence of an application to Mr Accum of 

 Compton Street, London, that ingenious chemist has 

 favoured us with a sight of all the blow-pipes which 

 he keeps for sale, and we have gladly availed our- 

 selves of his permission to represent several of them 

 in PlateLXII. 



A very common blow-pipe, for chemical and mine- 

 ralogical experiments, known by the name of Cron- 

 stad's Blow-pipe, is represented in Fig 1. It is the 

 same as the common blow-pipe, above mentioned, ex- 

 cept in having a globular ball at A. This unscrews 

 in its largest diameter, to remove the moisture which 

 may collect in it. The small pipe a, passing away 

 from the ball, enters into it, and projects nearly into 

 the centre, as is shewn by the dotted lines, by which 

 means the globe will hold more water than can ever 

 be collected in it in the course of one experiment, 

 without any danger of getting away at a. The mouth- 

 piece D is made of ivory, and the rest of the pipe of 

 brass ; the nose b, or aperture through which the air 

 issues, may be removed to screw on others of different 

 sized holes. The pipe has generally three of these 

 sizes ; the smallest but just large enough to admit a 

 bristle, and the largest only the size of a small pin. 



The blow-pipe represented in Fig. 2. is attributed 

 to Dr Black. It is simply a conical tin tube, of a 

 convenient size to be held in the mouth at a, and en- 

 larged to an inch diameter at the other end. The 

 jet b, fixed to it at one side, is, a short pipe soldered 

 into the" tube, and projecting inwards almost to its 

 centre on the outer end. It is made conical, and a 

 small jet b is stuck upon it. If well fitted, the fric- 

 tion will be quite sufficient to fasten it ; and any 

 number of jets may be adapted to fit on. This is a 

 very good kind of blow-pipe, as the large internal 

 surface of the conical tube effectually condenses the 

 vapour of the breath, and affords a lodgment for it 

 in the bottom of the tube. When it collects into a 

 quantity so a3 to be troublesome, it may be poured 

 out at the end a. 



Fig. 5. is a convenient blow-pipe. Its ivory 

 mouth-piece a, is fitted to the end of a brass tube 

 A ; and at the other end of this is soldered a small 

 cylindrical box B, from the centre of which the jet 

 b proceeds. This is fitted in by a joint, which al- 

 lows the jet to be placed at any angle with the tube, 

 a property which will frequently be found conve- 

 nient iii placing the flame in any direction. The 

 joint is formed by a part of the jet, at right angles 



to the nose b, being fitted through a hole in the box; 

 and the end, which comes through, rivetted down, at 

 least so far as to prevent it coming out The box 

 B has a lid c, which unscrews for the purpose of 

 wiping out the dampness. 



Fig. 4. is Dr Wollastou's ingenious portable blow- 

 pipe, which is remarkable for its neatness, and the 

 small space into which it may be packed. A is the 

 mouth-piece, b a second length of the tube, receiving 

 the conical end of the first, and (/ the jet, with a small 

 globe e, which has a hole through it to admit the 

 end of b. In the side of this is a hole, which, when 

 the two are put together, coincides with the tube of 

 the jet d. This pipe, when joined, has only the pro- 

 perties of the common blow-pipe before mentioned. 

 When its parts are separated, as in the figure, the 

 jet e is thrust into the large end of b, but the globe 

 is left projecting out of the end; then both these are 

 pushed into the tube A, at its large end, by which 

 means, when put up, it is only the size of A, which 

 is not larger than a small pencil, and may be always 

 carried in the mineralogist's pocket-book ; and in 

 many instances will prove extremely useful when a 

 better pipe is not at hand. 



Fig. 3. is a blow-pipe, which has been handed to_ 

 us by its inventor. It consists of two tubes A, B, 

 of a tolerable size, soldered together 'like a hammer.. 

 The jets are screwed in at a, and the end of them 

 projects some distance into the tube B, in order to 

 prevent the water from being blown out. The jet 

 b, at the opposite end, is for the escape of a part of 

 the air. When blowing with a small jet, the quan- 

 tity of air required is so small, that the operator 

 would find relief in opening another, as he would 

 then be enabled to breathe more frequently, and with 

 greater ease. 



It will readily be seen, that all the blow-pipes 

 above described have advantages peculiar to them- 

 selves, though the differences between them are but 

 trifling ; and any of them will perform well, if sup- 

 plied with a constant and equable stream of air, in 

 which lies the principal art of Rising the blow-pipe. 

 This is effected by the operator breathing freely 

 through his nostrils, in the most natural manner, 

 without breathing materially quicker or slower than 

 ordinary ; but at every expiration, throwing a por- 

 tion of air into the mouth, so as to inflate the cheeks,, 

 which, by their muscular action, condense the air, 

 and force it through the tube, into the flame, in a 

 continued stream, though the mouth is only supplied 

 at the interval of every respiration. To perform this 

 readily, requires some practice; and the facility of it 

 can only be obtained by habit, it being one of those 

 things which is not easily taught by words. If a 

 person finds any difficulty in the first attempt, he 

 will derive some advantage, from accustoming hiiru 

 self to breathe through the nostrils, first with the 

 mouth open, and then shut ; for in either of these 

 cases, the passage from the lungs through the mouth 

 is closed. Having acquired this habit, he should 

 begin to throw some of the air at each expiration 

 into the mouth, as above described ; suffering it to 

 escape regularly through to the pipe, or any other 

 tube held in the lips ; but it should have a larger 

 aperture than the jet of the blow-pipe, to render the 



Blow-pipe 



Wollas- 

 ton's port- 

 able blow* 

 pipe. 

 Plate 

 JLXII. 

 Fig. 4. 



New in- 

 vented 

 blow-pipe* 

 Plate 

 LXH. 

 Fig. 3. 



