250 Mr. Cavendish’s Account of fame 
glafs of vitriolic acid (landing near it ; but the thermometer 
which was dipped into it was five or fix degrees colder, which 
fee ms to be the caufe of the congelation beginning round the 
ball. 
In the afternoon a thermometer was dipped into the other 
half of the acid, where, as the weather had grown lefs cold, 
it flood above a minute at - 25 0 , without freezing ; then, how- 
ever, the acid froze, with the fame appearance as in the morn- 
ing, and at the fame time the thermometer rofe to — 4 0 , and 
became (lationary. 
This acid, being left in the air with the thermometer in it, 
was found in the evening at - 45 0 ; it however was not intirely 
frozen, being only thick as an unguent, which (hews that the 
unfrozen part mu (l have been of a different (Irength from the 
frozen part; but it does not appear whether (Ironger or weaker. 
The next morning it was frozen folid, though the cold was 
only half a degree greater. 
On Jan. 1 6th, this acid was again tried in the fame manner; 
it then fufrered a thermometer, whofe ball had been previoufly 
warmed in the hand, to be dipped into it, and remain there 
feveral minutes without freezing, though its temperature was 
— 35 0 . But on lifting up the thermometer, a drop fell from its 
ball into the acid, which immediately fet it a freezing, and 
it rofe up to — 4°|. 
10. On Dec. 22d, the fpirit of nitre (N° 168.) which a. 
few days before had been diluted with fnow, fo as to be re- 
duced to the (Irength of ,41 1, was divided into two equal parts, 
and expofed to the cold. On Dec. 29th, when the temperature 
of the air was - 17°!* one of thefe parts was found beginning 
to freeze ; the other was fluid, but began to freeze on dipping 
iu a thermometer ; the thermometer in both kept (lationary at 
