^^ff'ects of Heat mod/Jied it/ Cojnpression. \^\ 



Oh several occasions of the same kind, the fusible metal, 

 being forced through some very minute aperture in the 

 barrel, spouted from it to the distance of several yards, de- 

 positing upon any substance opposed to the stream a beau- 

 tiful assemblage of fine wire exactly in the form of wool. 

 I inunediately understood that the phaenomenon was pro- 

 duced by the superior expansion of the liquid over the solid 

 metal, in consequence of which the fusible metal was driven 

 through the iron as water was driven through silver* by me- 

 chanical percussion in the Florentine experiment. It oc- 

 curred to me that this might be prevented by confining along 

 with the fusible metal a small quantity of air, which, by 

 Yielding a little to the expansion of the liquid, would save 

 the barrel. This remedy was found to answer completely, 

 and was applied in all the experiments made at this timef. 



I now proposed, in order to keep the carbonate clean, to 

 inclose it in a small vessel ; and to obviate the difficulty of 

 removing the result at the conclusion of the experiment, I 

 further proposed to connect that vessel with an iron ramrod, 



• Eosays of Natural Ex-periments made in the Acaiiemie del Cimento, 

 translated by Waller, London, 163-1, page 117. The same in Musschen- 

 broek's Latin translation, Liigd. Bat. 17S1. p. 63. 



f I found it a matter of much difficulty to ascertain the proper quantity 

 of air which ought to be thus inclosed. When the quantity was too great, 

 the result was injured by diminution of elasticity, as I shall have occasion 

 fully to show hereafter. When too small, or when by any accident the whole 

 of this included air was allowed to escape, the barrel was destroyed. 



I hoped to ascertain the buUc of air necessary to give liberty to the expan- 

 sion of the liquid metal, by measuring the actual quantity expelled by known 

 heats from an open barrel filled with it. But I was surpristJ to find that the 

 quantity thus discharged exceeded in bulk that of the air w'hich, in the same 

 heats, I had confined along with the carbonate and fusible metal in many 

 successful experimerita. As the expansion of the liquid does not seem capable 

 of sensible diminution >)y an opposing force, this fact can only be accounted 

 for by a distention of the barrel. In these experiments then the expansive 

 force of the carbonic acid, of the included air, and of the fusible metal, 

 acted in combination against the barrel, and were yielded to in part by the 

 distension of the barrel, and by the condensation of the included air. My 

 object was to increase the force of this mutual action, by diminishing the 

 quantity of air, and by other devices to be mentioned hereafter. Where so 

 many forces were concerned, the laws of whose variations were unknown, 

 much precision could not be expected, nor is it wonderful that, in attempting 

 fo carry the compre-.sing force to the utmost,! should have destroyed barrels 

 iijiiu;nerab!e. 



K 4 longer 



