33^ ACTION or HEAT MODIFIER 



The method %• ^')* dofed at one end, and open at the other, of one foot 



adopted uiti- or more in length j it is evident, that by introducing one end 



mately was to . ^. -^ "* 



include the '"'** ^ turnace, we can apply to it as great lieat as art can 



fubjea in an produce, while the other end is kept cool, or, if necelfary, 



clofe theVpe^r- ^^po^ed to extreme cold. If, then, the fubftance which we 



ture by fufioni mean to fubjecl to the combined aftion of heat and prcflTure be 



introduced into the breech or clofed end of the barrel (CD), 



and if the middle part be filled with forae refradtory fubftance, 



leaving a fmall empty fpace at the muzzle (AB), we can apply 



heat to the muzzle, while the breech containing the fubjeft of 



experiment, is kept cool, and thus clofe the bar/el by any of 



the numerous modes which heat affords, from the welding of 



iron to the melting of fealing-wax. Things being then reverfed, 



and the breech put into the furnace, a heat of any required 



intenfily may be applied to the fubjedi of experiment, now in 



/ a ftate of conflraint. 



My firft application of this fcheme was carried on with a 

 lirft experiment common gun-barrel, cut off at the touch-hole, and welded 

 pttge^d'a'^d"^'' ^^^y. ft^ongly at the breech by means of a plug of iron. Into 

 welded, it 1 introduced' the carbonate, previoufly rammed into a car- 



tridge of paper or pafleboard, in order to proted it from the 

 iron, by which, in fome former trials, the fubjeft of experiment 

 J)ad been contaminated throughout during the adion of heat. 

 , I then rammed the reft of the barrel full of pounded clay 

 previoufly baked in a ftrong beat, and I had the muzzle clofed 

 like the breech, by a plug of iron welded upon it in a common 

 forge; the reft of the barrel being kept cold during .this 

 operation, by means of wet cloths. The breech of the barrel 

 -was then put horizontally into a common muffle, healed to about 

 25** of Wedgwood. To the muzzle a rope" was fixed, in fuch 

 a manner, that the barrel could be withdrawn without danger 

 inftance folder- f'oni aneKplofion*. Ilikewife, about this time clofed the muzzle 

 ed. of 



* This plate will be given in No. 54, being the fupplement to the 

 prefent volume. 

 ■ f On one occafion, the importance of this precaution was 

 ftrongly felt. Having inadvertently introduced a confiderable 

 quantity of moifture into a welded barrel, an explofion took place, 

 bet'ore the heat had rifen to rednefs, by which, part of the barrel was 

 fpread out to a flat plate, and the furnace was blown to pieces. 

 Dr. Kennedy, who happened to be prefent on this occafion, ob- 

 feived, that notwithftanding this accident, the time might come 

 when we ihould employ water in thefe experiments to aflTift the 



force 



