30 MODERN SCIENCE READER 



exploded powder was assumed to be the correct measure 

 of the pressure. 



Rumford made two series of experiments, but the charges 

 he employed were very small, his largest, with the excep- 

 tion of one by which his vessel was destroyed, being 18 

 grains or about l 1 ^ grams. 



From the first series Rumford deduced that with a 

 charge at a density of unity the pressure would reach 

 29,000 atmospheres. But, high as this result is, Rumford 

 considered it much too low, and from a second series, the 

 results of which were very discordant, he arrived at the 

 conclusion that the tension of exploded gunpowder such 

 as he employed, when filling completely the space at which 

 it was inclosed, w r as about 101,000 atmospheres. 



I may observe that the mode of firing the powder which 

 Rumford was compelled to adopt, viz., the heating of the 

 vessel in which the powder was confined by a red-hot ball, 

 would materially increase the pressure, and he further 

 accounted for the enormous pressures he gave not being 

 realized in guns, by assuming that the combustion of 

 powder in artillery and small arms was comparatively slow 

 and approximated to the rate of combustion in the open 

 air. From an examination, however, of Rumford 's appa- 

 ratus it is not difficult to conjecture both how he supposed 

 his pressures to be so high, and also how some of his results 

 were so discordant. 



Passing over several experimenters or writers on the 

 subject, I must refer to the researches of Bunsen and 

 Shischkoff, who in 1857 published the results of their 

 important investigations. The powder in their experi- 

 ments was not exploded, but deflagrated by being allowed 

 to fall in an attenuated stream into a heated bulb, in 

 which, and in the connected tubes, the products of combus- 

 tion were collected. 



The transformation under these conditions would not be 

 quite the same as if the powder had been exploded under 

 pressure, but a careful analysis was made both of the solid 



