MODIFIED by COMPRESSION. in 



the tube was encafed in- a folid mafs, before the heat had 

 reached the included moiflure. The difficulty was to catch 

 the fufible metal at the proper temperature 5 for when it was 

 fo hot as not to fix in a few feconds, by the contact of the 

 cradle and its contents, the water was heard to bubble through 

 the metal and efcape. I overcame this difficulty, however, 

 by firft heating the breech of the barrel, (containing a fuffi- 

 cient quantity of fufible metal), almoft to rednefs, and then 

 fetting it into a vefTel full of water, till the temperature had funk 

 to the proper pitch, which I knew to be the cafe when the 

 hilling noife produced in the water by the heated barrel cea- 

 fed ; the cradle, during the laft ftage of this operation, being- 

 held clofe to the muzzle of the barrel, and ready to be thruft 

 into it. 



On the 2d of May, I made my firft experiment in this way, 

 uling the fame air- tube as in the laft experiment, which was 

 equal in capacity to one-thirtieth of a cubic inch. Half a 

 grain of water was introduced in the manner juft defcribed. 

 The barrel, after an hour of red-heat, was let down by a 

 rope and pulley, which I took care to ufe in all experiments, 

 in which there was any appearance of danger. All was found. 

 The metals rulhed out fmartly, and a flafh of flame accompa- 

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

 lower one 14 . The contents of the inner tube had loft lefs 

 than 1 per cent., ftri&ly 0.84. The carbonate was in a ftate of 

 good limeftone ; but the heat had been too feeble : The lower 

 part of the chalk in the little tube was not agglutinated : The 

 chalk round the fragment of pipe-ftalk (ufed to introduce the 

 water), which had been more heated than the pyrometer, and 

 the fmall rod, which had moulded itfelf in the boll of the 

 ftalk, were in a ftate of marble. 



On the 4th of May, I made an experiment like the laft, but with 

 the addition of 1.05 grains water. After application of heat, the 



Vol. VI. — P.I. CL fire 



