326 
CAUSE OF THE SOLIDIFICATION OF BALSAM OF COPAIBA BY LIME 
AND MAGNESIA. 
BY M. ROUSSIN.* 
The cause of the solidification of balsam of copaiba has been until now either unknown 
or unappreciated. We know, for example, that genuine balsams of the best quality 
often resist solidification, whilst products of a very doubtful quality rapidly solidify. 
The following experiments, selected from a larger series, seem to throw some light upon 
the question. 
If balsam of copaiba of the very finest quality is mixed with a twelfth part of its 
weight of quicklime reduced to a very fine powder, (it is necessary to employ rich lime.) 
no sign of solidification takes place, and the substances might remain in contact for 
any length of time without undergoing any combination. If, into such a liquid combi¬ 
nation, enough water to hydrate the quicklime is incorporated by agitation, the tempe¬ 
rature becomes considerably raised, and in a few hours the entire mass solidifies into a 
very homogeneous pill-like consistence. The proportion of water required is almost ex¬ 
actly a third of the lime employed. 
On repeating the previous experiment with ordinary calcined magnesia, M. Roussin 
established,— 1 . That divers commercial balsams of copaiba contain a considerable pro¬ 
portion of water, which they will lose if exposed for a long time under a glass receiver, 
enclosing fragments of chloride of calcium or of carbonate of potash. 2. That the 
commercial calcined magnesia readily attracts the moisture of the air, and, after having 
been some time in a badly-stopped vessel, always contains considerable quantities of 
water, sometimes to the extent of 15 and 20 per cent. 
If a specimen of good balsam of copaiba is divided into two equal parts, and having 
properly dried the first portion under a receiver, and sufficiently hydrated the other 
by placing it in a damp vessel, each portion is then mixed with one-sixteenth its weight 
of recently calcined magnesia, the dried portion remains liquid, and the magnesia in 
great part even sinks to the bottom of the vessel, while the second portion, on the 
contrary, becomes a hard mass of pilular consistence. 
The above facts show the necessity of the agency of water in order to bring about 
the combination of the resin of the balsam of copaiba with the lime and the magnesia. 
M. Roussin purposes to develope these results in a more extended investigation.— 
Chemical Nexus. 
ON THE PRESENT STATE OF THE CHEMISTRY OF GAS-LIGHTING. 
BY HENRY LETHEBY, ESQ., M.B., ETC. 
Delivered at Birmingham before the Society of Gas Nnr/ine&'s. 
( Continued from page 288.) 
In order that the leading properties of the several combustible constituents of coal gas 
may be seen at a glance, I will direct your attention to this diagram, where I have ta¬ 
bulated not only the known constituents of gas, but also some of their allies, as the al- 
the two constituents of the ointment must be rubbed up to a most intimate admixture if it 
is to act well. The following are, then, the two formulae ;— 
Ijf Hydrarg. oxvdat. flavi, gr. xxx. 
(via humida parati). 
Ung. cotacei, ^ss. 
Miscc exactissiine et fiat unguent. 
Or, 1,1 Hydrarg. oxydat. flavi, gr. xxx. 
(via humida parati). 
Ung. cetacei, gj. 
M. exactiss. et flat unguent. 
* 4 Journal de Pharmacie et de Chimie,’ April, I 860 . 
