The Torricelli experiment is to be performed with ether instead of mercury. The room temperature in one case is $t_{1}=$ $30^{\circ}$, and in the other case $t_{2}=-10^{\circ}$, the air pressure in both cases is equal to $750 \mathrm{~mm}$ of mercury pressure. The density of ether is $\sigma_{1}=0.715$, that of mercury is $\sigma_{2}=13.6$; the vapor pressure of ether is $30^{\circ}$, $634.8 \mathrm{~mm}$ of mercury column pressure at $10^{\circ}$, and $114.72 \mathrm{~mm}$ of mercury column pressure at $-10^{\circ}$. How high is the ether column at the two temperatures?
If the Torricellian vacuum is filled with ether vapors, then at $30^{\circ}$ C, the height of the mercury column is $(750-634.8) \mathrm{mm}$. Since the heights of columns of different density liquids are inversely proportional to their densities in terms of pressure, if we want to replace this mercury column with an ether column, then at $330^{\circ} \mathrm{C}$

$$
\begin{array}{ll}
l_{1}:(750-634.8)=\sigma_{2}: \sigma_{1} ; & l_{1}=\frac{\sigma_{2}}{\sigma_{1}}(750-634.8)=2191 \mathrm{~mm} \\
\text { Similarly } & l_{2}=\frac{\sigma_{2}}{\sigma_{1}}(750-114.72)=12084 \mathrm{~mm}
\end{array}
$$

(Neuhold Özséb, Eger.)