224 



IGNITION FROM COMPRESSED AIR. 



Is it elec 

 tiicity ? 



Arguments 

 a<^ainst this. 



Tn a metallic 

 condenser we 

 cannot 'ee 

 what takes 

 place. 



We can in a 

 glass tube. 



(Glass flutes.) 



In examining the question whether the spunk be kindled by 

 electricity. I consider 



]sf, That no part of the instrument is insulated; and that 

 insulation is a necessary condition for producing sensible elec- 

 tricity with any of the machines we know. I s^y machines 

 that we know, because tlie animal electricity, that manifests 

 itself without insulation, is an exception to our mechanical 

 means, and cannot here be taken into consideration. 



2diy, The friction of the piston, which is a greasy body, 

 against a metallic substance, is not calculated to produce elec- 

 tricity. 



3dly, Experience demonstrates, that, unless during storms, 

 the atmosphere seldom exhibits any signs of electricity at the 

 height in which we breathe it ; and that we must search for 

 them with instruments in a more elevated region, or when elec- 

 tric clouds are passing over our heads. How then shall we 

 estimate the iniinitely small quantity of electric matter in a 

 cubic inch of air, or even less, which the instrument contains. 



Fourthly, It is not without great difficulty, that we can 

 kindle spunk with strong electric sparks. I have discharged a 

 large jar on spunk strewed with powdered resin, and it has re- 

 mained unkiudled, though the resin caught fire, and burned en- 

 tirely away. 



As long as (he instrument was made with metallic substances 

 only, we were obliged to confine ourselves to the exterior marks 

 of inflammation alone, without being able to assign the true 

 cause, or at least furnish proofs of it. For to guess is not suf* 

 ficient in natural philosophy ; we must demonstrate, in order to 

 give to facts that degree of certainty, which befits science ; and 

 this we cannot do here, without seeing what passes at the very 

 poiiit of inflammation. 



The means are very simple. Nothing is necessary, but to 

 substitute a glass for a metal tube. Those found in the shops 

 being too slight, I applied to Mr. Laurent, the inventor of glass 

 fluies, requesting him to procure me tiibes of a similar quality. 

 This artist, as much distinguished by his civility as by his ta- 

 lents, furnished me with three, which I fiited up. The first, 

 eight inches long by eight lines in diameter, did not kindle the 

 spunk. I'he second, nine indies long by six lines and three 

 quarters in diameter, kindled it completely. This being" de- 

 stroyed 



