366 Researches respecting the Laws of the [May, 
from 20° to 10°, and I have compared them with the numbers ob- 
served by Deluc. This is the object of the following tables :-— 
Calculation of the Olive Oil Thermometer from the Formula 
D, = 0°950667 T + 0°00075 T? — 000001667 Ts 
Degrees of mer-| Degrees of the olive oil thermometer, 
Liquid. | curial therm. 
Ty Calculated. | Observed. | Differences, 
80 80:00 | 80-0 0°00 
70 69°64 | 694 | —0-24 
60 59°37 | 59'S —0-07 
Olive 50 49:20 | 49-2 0-00 
oil 40 3912 | 39-2 +0°08 
, 30 | 2915 | 293 40°15 
20 19°30 | 19°3 0°00 
10 9°58 9°5 —0-08 
0 0-00 0-0 0-00 
M. Deluc at different times put the olive oil thermometer into a 
freezing mixture which sunk the mercurial thermometer to — 14°; 
and he says that the oil thermometer stood nearly at the same degree 
as long as the oil continued liquid. This result agrees with our 
formula; for if we suppose T = — 14, the formula gives D, = 
— 13°21. 
But when the oil began to solidify, the oil thermometer sank all 
at once much more than the mercurial thermometer. The oil sank 
altogether into the bulb. It was obviously the congelation that pro- 
duced this sudden effect; for, after it had taken place, if the tem- 
perature was elevated, the mercurial thermometer began to rise im-’ 
mediately ; but the oil thermometer remained stationary for a consi- 
derable time ; no doubt the time necessary to liquify the oil. When 
once melted, the oil speedily rose as high as the mercury, and con- 
tinued its usual dilatation. Deluc supposes that it was the absence 
of air which enabled the oil to acquire so great a degree of cold 
without freezing, though it would have congealed in the open air ; 
but it appears from the experiments of Sir Charles Blagden that 
neither the exclusion of air nor rest are absolutely necessary for this 
effect, though they may contribute to it. 
We see by these phenomena, 1. That olive oil in certain circum- 
stances may be cooled down much beyond its ordinary degree of con- 
gelation without freezing. 2. That it diminishes in bulk, like mer- 
cury, when it freezes. This is quite obvious, as the frozen portions 
sink to the bottom of the vessel. 3. That to the very moment of its 
becoming solid it continues exactly, or very nearly, to contract ac- 
cording to the usual Jaw. This appears to be the case with mercury, 
