C.M. Warren on a Process of Fractional Condensation, 327 
bushel, of acorns or nuts thrown upon their surface? , 
then, if trees will grow on prairies, do not isolated or widely 
separated clusters of trees insensibly cover a wider area? Some 
_ of these trees have lived there for ages; their trunks are strong 
and thick; their branches widely expanded, and their fruits are 
_ swept far away by the impetuosity of autumnal storms; never- 
theless, their domain is restricted, by the nature of the ground, 
_ totheir own narrow limits; these they never pass. 
[Zo be continued. ] 
—On a Process of Fractional Condensation: applicable 
to the Separation of Bodies having small differences between their 
, Boiling-points ; by C. M. WARREN.’ 
: Th is well known that the process in general use for the ee 
mate analysis of mixtures of volatile liquids,—viz: that 
| pe fractional distillation, either from a tubulated retort or 
oma flask with bulbs, as proposed by Wurtz,’—affords but 
: leak imperfect and unsatisfactory results, and not unfrequently 
8 
to gross errors and misconceptions, except in those cases 
‘tn which the boiling-points of the constituents are widely differ- 
ent, M in which some auxiliary method can be advantageously 
employed. 
The want of a more efficient process for effecting such sepa- 
Tations has long been recognized. There are numerous natural 
and artificial products, of the highest scientific interest,—such 
‘petroleums, essential oils, tars, and other mixtures of oils ob- 
tained by the distillation, under varied circumstances, of bitu- 
minous, vegetable, and animal substances,—of which it may at 
least be said that we have but very imperfect knowledge,—l 
pent almost say no knowledge, except such as could be de-. 
In re fad ft rsevering and pro- 
peated instances, apparently after pe ‘ | 
tracted efforts, investigators have been forced to assert either the 
iipossibility, or their inability, to obtain, from such mixtures, 
Odies of constant boiling-point,—a property which is generally 
a4 tom the Journal of the Acad. Arts and Sciences, Boston, May 10th, 1864. 
Aunales de Chimie et de Physique, [3], sli, 182. 
