BY COMPRESSION-. ]5 



Th<5 metals ruslied out smartly, and a flash of flame accompa- 

 nied the discharge. The upper pyrometer gave 24°, and the 

 lower one 14°. The contents of the inner tube had lost less 

 tlian 1 per cent,, strictly 0.84. The carbonate was in a state 

 of good limestone ; but the heat had been too feeble : The 

 lower part of the chalk in the little tube was not agglutina- 

 ted ; The chalk round the fragment of pipe-stalk (used to in- 

 troduce the water), which had been more heated than the 

 pyrometer, and the small rod, which had moulded itself in the 

 boll of the stalk, were in a state of marble. 



. On the 4th of May, I ma<le an experiment like the last, but Another with 

 with the addition of 1.05 grains water. After application of-j-g^p qq^o^' 

 heat, the fire was allowed to burn out till the barrel was black. 

 The metal was discharged irregularly. Towards the end, the 

 inflammable air produced, burnt at the muzzle, with a lam- 

 bent flame, during some time, arising doubtless from Tiydrogen 

 gas, more or less pure, produced by the decomposition of the 

 water. The upper pyrometer indicated 36**, and the lower 

 one 19**. The chalk which lay in the outer part of the lai^e 

 tube was in a state of marble. The inner tube was united to 

 the outer one, by a star of fused matter, black at the edges, 

 and spreading all round, surrounding one of the fragments of 

 porcelain which had fallen by accident in between the tubes. 

 The inner tube, with the starry matter adhering to it, but 

 without the coated fragment, seemed to have sustained a loss 

 of 12 per cent., on the original carbonate introduced. But, 

 the substance surrounding the fragment being inappreciable, 

 it was impossible to learn what loss had been re:illy sustained. 

 Examining the little tube, I found its edges clean, no boiling 

 over having taken place. The top of the small lump of chalk 

 liad sunk much. When the little tube was broken, its con- 

 tents gave proof of fusion in some parts, and in others, of the 

 nearest approach to it. A strong action of ebullition had 

 taken place all round, at the contact of the tube with the car- 

 bonate : in the heart, the substance had a transparent granu- ' 

 iar texture, with little or no crystallization. The small piece 

 cf lump-chalk was united and blended with the rammed pow- 

 der, so that they could scarcely be distinguished. In the lower 

 part of the carbonate, where the heat must hnve been weaker, 

 ^le rod had acted more feebly on the "tube, and was detached 



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