ihe Point of Mercurial Congelation . * 3 2r 
The table will fully explain the procefs. I was in hopes, by 
(hitting the inftruments into three freff mixtures, I fhould 
have been able to have produced a greater degree of cold than 
by one only ; yet it did not. I added more fpirit of nitre, but 
without effect. At lob. f 35" I took out the apparatus, and 
raifed the bulbous end to make the quicktilver run, but found it 
was frozen, fo that it did not alter its figure in the lead:. I then 
placed it in the mixture, where it confined till 10 h. 1 i when 
I made another trial as before, but without perceiving anv alte- 
ration : however, to be more certain of its being frozen, I pro- 
poled to take out the thermometer ; but all the flrength in my 
fingers could not move it in the lead:, fo that myfelf and offi- 
cers, who flood by, were convinced it was frozen fad. I then 
made another mixture in hopes to augment the cold, and make 
the inclofed thermometer (F) delcend ; however, feeing no alte- 
ration, I went into the houfe to warm mvfelf, and on my 
* 
return found it had fallen 3 0 . I tried the coldnefs of the mix- 
ture by different fpirit thermometers, and afterwards drifted the 
indruments into the mixture from whence I had taken them ; 
but this diminiffed the cold bv the thermometer, fo that I 
re-placed them again in the third mixture, and the quickfilver in 
the thermometer defeended again to its former point 448°. I 
continued obferving it fome minutes, when the cold obliged 
me a fecond time to retire, and on my return found both the 
thermometer and apparatus riling : on dipping a fpirit ther- 
mometer into the mixture, I found it had a confiderable degree 
of coldnefs, and both the apparatus and mercurial thermometers 
were nearly equal. I then took them out, and the quickhlver 
in the cylinder was as fluid as when it was firfl poured in. 
I ffould have obferved, that during the time I was pouring 
in the fpirit of nitre at the beginning of the operation, I was 
*U u 2 fo 
