«6 



DE. GOODMAN ON LIGHT, HEAT. 



Exp. This experiment was repeated again and again, 

 and still do explosion occurred; but there were noticed, 

 besidce the flame, several red-hot pieces of potassium, 

 which fell down to the depending portion of the 

 bladder. 



Exp. 9. — The bladder was now filled with common air, 

 and the hammer again used for percussion. The applica- 

 tion of several smart blows produced no explosion, although 

 the bladder was filled with incandescent potassium, bril- 

 liantly luminous even in broad daylight. 



The exudation of potassium was now placed beyond 

 doubt; for the finger detected the soapy feel of potash, and 

 the white appearance of this body was observable in every 

 direction throughout the bladder. 



It was now discovered that the absence of report was 

 owing to the dilatation of the crevice through which the 

 potassium exuded; for large pieces of red-hot metal were 

 projected at every stroke of the hammer. 



I very much doubt whether by art I shall be enabled 

 again to witness what by accident has thus been so magnifi- 

 cently thrown in my way. 



Exp. 10. — By this time a new percussion apparatus was 

 constructed of wrought steel, of considerable strength. The 

 bore was about | of an inch, and one inch in depth. The 

 piston was also of steel, and fitted in an air tight manner 

 the bore of the cylinder. A small hole drilled to within f 

 of an inch of the former bore, served for the insertion of the 

 thermometer ; and the whole, after being charged with a 

 portion of potassium was placed between the extremities 

 of a vice. Considerable pressure was employed ; but in no 

 instance could there he obtained any certain indication of 

 more than half a degree of increased heat given to the cylin- 

 der by compression. 



Another cylinder was now constructed, also of steel, 

 dimensions as before ; but the bore was made to extend 



