1821 .] Dr, Clarke upon a new Bloivpipe, 4ij9 



two hours continuance may be maintained, of the most perfect 

 shape and uniform temperature, uninterrupted by casual currents 

 from the pneumatic reservoir. 1' 



4. The troublesome interruptions caused by the ejection of 

 water, while supplying the apparatus with air, which were com-' 

 mon in the old instrument, do not happen in the new one. 



5. The new instrument may remain unemployed for any length 

 of time, being always ready for instantaneous use, and requiring 

 no other preparation than merely that of hghting the wax taper 

 employed to supply the flame. • 



The manner in which this instrument was brought to its pre- 

 sent state of perfection, affords an anecdote which may not be 

 uninteresting to your readers ; because it will show the force of 

 mechanical skill as it is sometimes remarkably conspicuous iu 

 uneducated minds. A servant of mine, who has been frequently 

 employed in attendance during my lectures in mineralogy, see- 

 ing me reject the old instrument as unfit for the uses to which I 

 wished to apply it, asked me the reason of my setting it aside. 

 To this I answered that the short space of time in which it con- 

 tinued to propel the flame rendered it inconvenient ; and that I 

 would rather use the common mouth blowpipe than be liable to 

 such frequent interruption from the necessity of supplying it 

 every five minutes with fresh air. This caused him to inspect 

 the inside of the instrument ; when he simply observed, '' It is 

 very awkwardly contrived; J could make a better myself! " and 

 in good earnest, without further communication with me upon 

 the subject, he fell to work, and produced the new improved 

 apparatus, which it is my present purpose to describe, and to' 

 make as generally known as possible. The inventor's name is' 

 Johnson Tofts. Upon the principle which he has adopted for 

 the improvement of his blowpipe, such instruments are now 

 manufactured in London. By means of one of these instru- 

 ments, gold might be exhibited in a state of continual fusion 

 for almost any length of time. 



A trial has been made of the use and powers of this improved' 

 blowpipe throughout an entire course of public lectures in mine- 

 ralogy before the University, with such success, as to produce 

 sufficient proof of its convenience and efficacy. The effects 

 witnessed when oxygen gas was employed exceeded those 

 usually produced by the same agent from a gasometer; owing to 

 the condensed state in which the. gas was propelled ; while the 

 cone of flame was much more manageable. Platinum wire of 

 some thickness was fused ; platinum foil offered no resistance 

 whatever. The steel mainspring of a watch underwent brilliant 

 combustion ; and even when the instrument is charged with 

 common atmospheric air, thin cuttings oi platinum foil sustain 

 an instantaneous fusion. 



Had we possessed this apparatus before the gas bloivpipe was 

 invented, many of the results obtained by that powerful instru- 



