Chemistry. 199 
13 . Maximum density of Water. ^ Our readers are already 
acquainted with the very ingenious method by which Dr Hope 
determined the maximum density of water to be between 39^ 
and 40° of Fahrenheit. (See Edin. Transactions , vol. v. 
p. 379.). Professor Moll of Utrecht has been very recently oc- 
cupied with the same inquiry, in which he employed the very 
same method as Dr Hope. The result of his observations is, 
that the point of maximum density lies between 39° and 40°, 
which shews the great accuracy of Dr Hope’s determination. 
Letter from Professor Moll. 
14. On the Effect of Heat and Pressure on certain Fluids . — - 
From a number of curious experiments on this subject by 
M. le Baron Cagnard de la Tour, he draws the following con- 
clusions: 1. That alcohol, naphtha) and sulphuric ether, sub- 
mitted to heat and pressure, are converted into vapour in a 
space a little more than double that of each liquid. % That an 
increase of pressure, occasioned by the presence of air, present- 
ed no obstacle to the evaporation of the liquid in the same 
space, but only rendered its dilatation more regular. 3. That 
water, though susceptible of being reduced into very compres- 
sed vapour, has not yet been submitted to perfect experiments, 
on account of the imperfect closing of the digester at high 
temperatures, and also on account of its action on tubes of glass. 
Baron de la Tour afterwards found, that when ether was con- 
verted into vapour, in a space less than twice its original volume, 
which happened at a temperature of 320° of Fahrenheit, it ex- 
erted a pressure of between 37 and 38 atmospheres. When 
alcohol was reduced into vapour in a space rather less than 
thrice its original volume, which happened at a temperature of 
405°, it exerted a pressure of 119 atmospheres. Our author 
also determined, that at a temperature near that of melting zinc 
(about 700° of Fahrenheit) water may be converted into vapour 
in a space nearly four times that of its original volume. 
15. Mr Phillips'' Analysis of Ur unite.— ~ According to M. Ber- 
zelius, u uranite is a compound oxide of uranium with lime and 
“ water, or a true salt with a base of lime, in which the oxide 
“ acts as an acid.” Mr R. Phillips has, however, found it to 
