440 Miscellaneous Intelligence. 
mediately rise up to between 230° and 240°. The same effect 
may be observed by tying the bulb up with the substance in a 
piece of flannel or lint, and introducing it into an atmosphere 
of steam. 
The substances possessing this property are those, the solu- 
tions of which require a higher temperature for their ebullition 
than the solvent (in this case water) does, and their power is in 
proportion, as would readily be anticipated, to the elevation of 
the boiling point of the solution. The following are the tem~- 
peratures produced in this way by some’substances. The first 
column of figures indicates the temperature obtained by the 
method first mentioned. The second column those by the 
second method : 
Sulphate of Magnesia . . 218° . . . 214° 
Tartrate of potassa . . 236° . . . 230° 
POOsMe GIG, 536. 4 tal, 220° se 2 sah ee 
Bier aeedcoas sc Mics Sok, ree aaa a oo 
Muriate of ammonia . . 230° . . . 227° 
CHIE AGIOS a4 wt pie ata aU 3) ck) 5 a 
Ee ot aoe inl inna oh stn i) eOr uk sie al, 
Nitrate of magnesia. . . 236° . . . 236° 
Nitrate of ammonia . . . 236° . . . 240° 
Acetate of potash... ..., 244°. *.  . 258° 
Subcarbonate of potash. . 258° . . . 262° 
Potash...» ssuy.. s,'* .» 900° and upwards, 
This effect evidently depends upon the attraction of the sub- 
stances for water. It enables them, when in contact with the 
vapour, to condense it, and the heat evolved by the conden- 
sation is that which principally raises the temperature. It is 
not, however, necessary to enlarge on the explanation, but I am 
anxious here to make my acknowledgments to M. Gay-Lussac 
for the correction of an error into which I had fallen. The 
observations, when first written, were, from circumstances, sent 
to Paris, and have since that been inserted in the Annales de 
Chimie. I had said incidentally, and without reference to 
sufficiently careful experiments, that vapour rising from a 
boiling. aqueous solution ofa salt was of the same temperature as 
that rising from boiling water under the same pressure. M. 
Gay-Lussac, remarking on this statement, stated, that the tem- 
perature of the vapour was always that of the solution from 
whence it rose, I have since then made various experiments 
on the subject, and found, (as I expected,) that philosopher 
correct. But I was considerably surprised by the difficulty of 
getting accurate results; and it was only by having a double 
boiler, which contained solution between its sides and at the top, 
as well as within, by heating the thermometer up to high points, 
and letting it cool in the vapour, by operating for long periods 
