BY COMPRESSION. |25 



The lever, too, was lengthened, by joining to the bar of ivon, 

 a beam of wood, making the whole ten feet in length, in 

 this manner, a pressure upwards was applied to the barrel, 

 equal to the weight of lOcwt. 



In the former method, in which the barrel stood with its Observaficns 

 muzzle upwards, the weight was applied while the metal was ^"p^^^j^^J^J* '^^ 

 liquid. In this case, it was necessary to let it previously con- 

 geal, otherwise the contents would have run out in placing 

 the barrel in the muffle, and to allow the liquefaction essential 

 to these trials, to be produced by the propagation of heat from 

 the muffle downwards. This method required, therefore, in 

 every case, the use of an air-tube ; for without it, the heat 

 aeting upon the breach, while the metal at the muzzle was 

 still cold, would infallibly have destroyed the barrel. A great 

 pumber of these experiments failed, with very considerable 

 waste of the fusible metal, which, on these occasions was 

 nearly all lost. But a few of them succeeded, and afforded 

 very satisfactory results, which I shall now mention. 



In November 1S03, some good experiments were made in Successful ope^ 

 this way, all with a bore of 0.75, and a pressure of 10 cwl;. rations. 



No, 3. — On the 19th, a good limestone was obtained in an 

 experiment made in a temperature of 21'-', with a loss of only 

 1.4 per cent. 



No. 4.— »^n the 22, in a similar experiment, there was lit- 

 tle exudation by the muzzle. The pyrometer gave 31°. The 

 carbonate v^a.s in a porous, and almost frothy state. 



No. 5. — In a second expei-iment, made the same day, the 

 Ijeat rose to 37" or 41". The substance bore strong marks 

 of fusion, the upper part having spread on the little tube : 

 the whole was very much shrunk, and run against one 

 side. The mass sparkling and white, and in a very good 

 state. 



No. 6. — On the 25th, an experiment was made with chalk, Failure of one 

 and some fragments of snail shell, with about half a grain of ^^^''^ barrels. 

 water. The heat had risen tjp near 51° or 49°. The barrel 

 had been held tight by the beam, but was rent and a little 

 swelled at the breech. The rent was wide, and such as has 

 always appeared in the strongest barrels when they failed. 

 The carbonate was quite calcined, it had boiled over the little 

 tube, and was entirely in a frothy state, with large and dis- 

 tinctly 



