llS On a 7iew Jutminating Mercurv. 



which the explofion had made in the fides of the piece, that 

 the fracrments were not removed without great labour. 



Exp. 2. Another cad iron cafe was prepared, of the fame 

 fize as tlic former, with a chamber a!fo cyhndvical, but 

 ti'rouoht in a tranfverfe direftion, and of a greater length 

 than diameter ; the thicknefs of metal at each exti-cmity not 

 being more than a. quarter of an inch. This cafe was filled 

 with nearly five ounces troy of the mercurial powder, and 

 placed in the fame carronade. Three twelve-pound fliot 

 were next introduced, and brought into clofe contact with 

 the upper furface of the cafe, as well as with each other. 

 The gun a fecond time withllood the explofion : the cafe was 

 divided, acrofs the middle of the chamber, into two equal 

 parts; that adjoining the breech was, as in the former ex- 

 periment, much flawed, and left iuHiiovcable; that neareft 

 to the muzzle was alfo tnuch flawed, but driven out with the 

 fhot. All the three fliot were broken ; the two lower being 

 divided into feveral pieces, and the upper one cracked through 

 the centre. 



The report was {'o feeble, in both experiments, that an 

 inattentive perfon, I am confident, would not have heard it 

 at the diftance of two hundred yards. 



Exf>. 3. It was found fo difficult to extraft the fragments 

 of the cafe remaining in the carronade after the laft experi- 

 ment, that a channel was drilled through them to the vent- 

 hole of the piece. It was tlicn charged with fix ounces troy 

 of the mercurial powder, made up as a cartridge, which did 

 not occupy above one-half of the diameter of the bore. A 

 wad was placed over the powder, dry fand fuperadded, to fill 

 all vacuities, and the c;uii filled to the nuizzle with two 

 twelve-pound fliot. A block of w'ood was fet at a fniall dif- 

 tance, to receive the imprcflion of the iliot, and the powder 

 was inflamed as ufual. The carronade fliill refifted. One of 

 the Ihot was fplit into two pieces; and the block of wood 

 \\as driven to a confiderablc difiance, but not penetrated by 

 the fliot above the depth of one inch. The report was fome- 

 what louder than the former ones. In all three inftaneeSy 

 a coufiderable recoil evidently took place. I prefunie, there- 

 fore, that in the firft experiment related in the fifth feftioji, 



there 



