i^6 Mr , Cavendish’s Account of 
required to produce that effeft, when it is performed in a more 
rapid manner. 
Thefe experiments confirm the truth of the conclufions I 
drew from Mr. M c Nab’s former experiments; for, firft, 
there is a certain degree of ftrength at which fpirit of nitre 
freezes with a lefs degree of cold than when it is either 
ftronger or weaker ; and when fpirit of nitre, of a different 
ftrength from that, is made to congeal, the frozen part 
approaches nearer to the foregoing degree of ftrength than the 
unfrozen. Likewife this ftrength, as well as the freezing 
point correfponding thereto, and the freezing point anfwering 
to the ftrength of ,54, come out very nearly the fame as I 
concluded from thofe experiments ; for by the prefent experi- 
ments they come out ,418, — 2%%., and —31°, and by the for- 
mer ,411, — i°|, and —31°. But the freezing point anfwering 
to the ftrength of ,38 is totally different from what I there 
fuppofed. This muft have been owing to the ftrength of that 
acid having been very different from what I thought it; which 
is not improbable, as its ftrength was inferred only from the 
quantity of fnow which was added to it in finding the degree 
of cold produced by its mixture with fnow. 
After the foregoing experiments were finifhed, Mr. M c Nab 
made fome more for determining the freezing points both of 
the decanted and undecanted part ; but for want of a fufficient 
explanation of the manner in which they were executed, I 
have not been able to make any ufe of them. In their prefent 
ftate they fhew much appearance of irregularity ; but this 
would very likely have been cleared up, if the circumftances 
had been more fully detailed. 
On 
