*3°4 Mr. Hutchins’s Experiments for afcertamitig 
experiments made in a different manner by my own fug- 
geftion ; and, laffly, an account of mercury frozen in the open 
air without the aid of any artificial cold, which will be found 
to corroborate the preceding experiments, and determine the 
exabt point of congelation to be at 40° below the cypher. I 
have been careful to mark down every circumlfance attending 
the experiments, and have added a few obfervations to each of 
them, to elucidate any uncommon phenomena that occurred. 
If thefe experiments fhould be agreeable to the Royal So- 
ciety, the merit mu ft be attributed to the excellent inftrudtions 
they tranfmitted to me, which left me nothing to do but to 
follow them ; yet I cannot avoid doing juftice to the in- 
genious Dr. black, Profeflor of Chemiftry at Edinburgh, 
who favoured me with fome remarks on the experiments I 
made in 1775 to freeze quickfilver, and fir ft fuggefted this 
method of afeertaining the point of congelation, which I had 
the honour of communicating to the Royal Society by the 
means of samuel wegg, efq. whofe attention to promote 
the views of the Society can only be equalled by that liberality 
of lentiment and great goodnefs of heart which makes him 
encourage even the moft feeble attempt than can in the leaf! 
tend to the improvement of knowledge. 
THOMAS HUTCHINS. 
