144 RESEARCHES ON THE VOLATILE HYDROCARBONS. 
ceased to have any action. The thermometer bulb extended into the liquid* nearly 
to the bottom of the retort. A second thermometer was attached, by means of 
flexible bands, to the side of the one in the retort; the bulb being placed, during 
ebullition, at a point midway between the centre of the cork (— 5’) and the upper 
end of the mercurial column, viz. at 35. A paper screen, closely fitting the ther- 
mometer spindle, was placed across at the top of the cork. With the retort neck 
slightly inclined upward, and cooled to prevent the escape of vapor, ebullition was 
continued for considerable time, until the mercury in the thermometer ceased to rise. 
The lamp being removed for the moment, the neck of the retort was then turned 
downward, and quickly inserted in a Liebig’s condenser. On replacing the lamp, dis- 
tillation commenced almost immediately at 79°. 
Observations. — 
Temperature. Time. Temper. by Side Thermom. 
é h. m. 
79.0 at 2.40 i 
} 5 minutes. 
79.2 “ 245 15 22°, 
79.4 “ 8.0019 « 24°. 
79.5 « 3.12 720 « 25°. 
79.6 «“ 882018 26°. 
79.6 « 3.50 26°: 
common specific gravity bottle is not suited to this purpose. Indeed, with a volatile body that bottle cannot 
serve for an accurate determination at any temperature. A reforrn in this regard being highly 
desirable, I would call attention to a specific gravity bottle which I obtained a few years ago 
from Fastré, in Paris, which is admirably adapted for taking specific gravities, even of volatile 
liquids, at a low temperature. The accompanying figure represents this bottle of one half its 
natural size. Who was the author of this particular form I am not informed, although it may 
have been already noticed in some publication. A bottle analogous to this is figured by Schiel 
(“ Hinleitung in das Studium der organischen Chemie,” page 76); but his bottle has an oval 
bottom, which makes it less convenient. The particular advantage of this bottle over the more 
common one, which advantage Schiel omits to notice, consists in this: that the space or chamber 
above the line on the capillary neck is large enough to allow for the expansion of the liquid 
consequent upon the elevation of temperature from 0° to that of the surrounding air; and that 
the ground stopper fits so closely that no perceptible loss from evaporation can take place during 
the time occupied by an experiment. 
In order to furnish determinations of the specific gravities of the bodies to be treated of in these researches, 
which shall be comparable with corresponding determinations by other observers, I shall generally record one 
or more special determinations made for this purpose. 
* For critical remarks on the question of propriety of placing the thermometer bulb in the liquid, ete.; and 
for further details of the method of taking boiling-points, especially at low temperatures, see the accompanying 
Memoir, “On the Influence of C, H, on the Boiling-points in Homologous Series of Hydrocarbons,” ete. 
