148 EFFECT'S of HEAT 



No. 9. — An experiment was made with chalk, in a little 

 tube ; to this, one grain ef water was added. I had intended to 

 work with 4 cwt. only ; but the barrel was no fooner placed, 

 than an exudation of metal began at the muzzle, owing, doubt- 

 lefs, to the elafticity of the water. I immediately increafed 

 the prefTure to 8.1 cwt. by removing the weight from the 

 bucket, when the exudation inftantly ceafed. I continued the 

 fire for three quarters of an hour, during which time no exu- 

 dation happened ; then all came out remarkably clean, with 

 fcarcely any contamination of metal. The lofs amounted to 

 2.58 per cent. The fubftance was tolerably indurated, but had 

 not acquired the character of a complete ftone. 



In thefe two laft experiments, the bore being fmall, a pyro- 

 meter could not be admitted. 



On the 5th of July 1804, I made three very fatisfactory ex- 

 periments of this kind, in a barrel with the large bore of 0.75 

 of an inch. 



No. 10. — was made with a comprefling force of only 3 cwt. 

 A fmall eruption at the muzzle being obferved, water was 

 thrown on the barrel : the pyrometer gave 21 : the chalk was 

 in a firm Hate of limeftone. 



No. 11. — with 4 cwt. The barrel flood without any erup- 

 tion or exudation, till the heat rofe to 25 °. There was a lofs 

 of 3.6 per cent. : the refult was fuperior, in hardnefs and trans- 

 parency, to the laft, having fomewhat of a faline fracture. 



No. 12. — with 5 cwt. The refult, with a lofs of 2.4. per 

 cent., was of a quality fuperior to any of thofe lately obtained.. 



These experiments appear to anfwer the end propofed, of af- 

 certaining the leaft preffare, and loweft heat, in which lime- 

 ftone can be formed. The remits, with various barrels of 

 different fizes, agree tolerably, and tend to confirm each other. 

 The table fhews, when we compare numbers 1, 2, 8, 10, 11, 

 12, That a preffare of 52 atmofpheres, or 1700 feet of fea, is 



capable 



