r 3*3 ] 



SECT. LV. 



The ufe of the Pocket-Laboratory, as here de- 

 fcribed, is chiefly calculated for a travelling mine- 

 ralift. But a perfon who is always refiding at 

 one and the fame place, may by fome fmall altera- 

 tion make it more commodious to himfelf, and 

 avoid the trouble of blowng with the mot^th. 

 For this purpofe he may have the Blow-pipe 

 go through a hole in a table, and fixed under- 

 neath to a fmall pair of bellows with double bot- 

 toms, fuch as fome of the glafs- blowers ufe, and 

 then nothing more is required, than to move the 

 bellows with the feet during the experiment •, but 

 in this cafe a lamp may be ufed inftead of a candle. 

 This method would be attended with a ft ill greater 

 advantage, if there were many fuch parts as fig. 3. 

 tab. 1. the openings of which were of different 

 dimenfions : thele parts might by means of a fcrew 

 be fattened to the main body of the Blow-pipe, and 

 taken away at leifure. The benefit of having thefe 

 nozzles, if I may be permitted to call them fo, of 

 different capacities at their ends, would be that of 

 exciting a flronger or weaker heat as occafion 

 might require, lc would only be neceffary to ob- 

 ferve, that in proportion as the opening of the pipe 

 (nozzle) is enlarged, the quantity of the flame 

 muft be augmented by a thicker wick in the lamp, 

 and the force of blowing increafed by means of 

 weights laid on the bellows. A much intenfer 

 heat would thus be procured by a pipe of a consi- 

 derable opening at the end, by which the experi- 

 ments might undoubtedly be carried farther than 

 wiph the common Blow-pipe, 



SECT. 



