424 
COPAL RESIN. 
to destroy life, the extracts derived from the matters vomited by these animals, or from 
the fluids contained in their stomachs after death (when vomiting was artificially pre¬ 
vented), were found to produce on frogs unmistakably the effects characteristic of the 
presence of one of the cardiac poisons. Three dogs were killed in this way; and in each 
case the results obtained were perfectly satisfactory. 
Note. —Received 18th May, 1865. 
We have now to add to the list of “cardiac poisons” the Manganja, an arrow-poison, 
brought from the Zambesi Expedition by Dr. Kirk. Our attention was directed to this 
substance, which is the fruit of an Apocynaceous plant, by Dr. Sharpey, who informed 
us of the results of experiments he had made on its action; and we owe to his kindness 
the opportunity of confirming his observations by our own experiments .—Proceedings 
of the Royal Society , May 18, 1865. 
TEST FOR OTTO OF ROSES. 
Hager mixes five drops of the otto to be tested with twenty drops of pure concen¬ 
trated sulphuric acid. Whether the oil be adulterated or not, a thick yellowish-brown 
or reddish-brown mixture results. When this mixture is cold, it is shaken up with 
three drachms of absolute alcohol. If now the otto is pure, a tolerably clear yellowish- 
brown solution results, which, after heating to boiling, remains clear. But if the otto 
is adulterated with geranium, palm rose, or pelargonium oil, the solution remains very 
cloudy, and in some cases a darker fluid separates, in which a deposit forms. On heat¬ 
ing this solution, the sediment melts together, and from the size of the mass the author 
infers the degree of adulteration. If, for example, the mass has one-fourth the volume 
of a drop, he concludes that the otto was mixed with at least one-third of foreign oil. 
If the otto is adulterated with spermaceti, this substance separates and floats on the 
surface of the solution, or remains suspended in the liquid as a scaly crystalline mass. 
The above test is founded on the circumstance that pure otto of rose forms, with strong 
sulphuric acid, a resinous substance, which is completely soluble in absolute alcohol; 
while the substance formed with other oils is only partially soluble. Guibourt has ob¬ 
served that the odour of pure otto is not affected by mixture with strong sulphuric 
acid, but if other oils are present a disagreeable odour is developed.— Chem. News, 
from Zeitschr.fiir Analyt. Chem. 
COPAL RESIN. 
To clear up any of the doubts which exist as to the true source or rather sources of 
this resin, would be to solve one of the many problems in economic botany. The term 
Copal, as is well known, is applied in commerce to most clear resins capable of producing 
a colourless varnish; for instance, East Indian Copal or Piney Varnish is produced by 
Vateria indica, L., a tree of the Natural Order JDipterocarpacece, while the African 
copals are undoubtedly the produce of Leguminous trees. The source of gum 
anime is another of these economic puzzles. One of the differences between these two 
resins—copal and anime—is that the former is mostly very clear and almost colourless, 
while the latter is always of a brownish tint. Both resins are sometimes rough on the 
surface, caused by the action of sand while the resin is in a soft state. The trees grow 
in the neighbourhood of the seashore, and the resin exuding trickles down and buries 
itself in the sand beneath. This roughened surface, called at Zanzibar “ goose skin,” 
is, of course, found only on the resin which has been buried, but the distinguishing cha¬ 
racters of the resins themselves are so well known as hardly to need mention; what 
we are chiefly concerned about is to know how many distinct plants furnish the Copal 
of commerce. 
Lieut -C r \. Playfair, H. M. Consul at Zanzibar, has recently transmitted to the Kew 
Museum, m answer to a request of the late Sir W. J. Hooker, some fine specimens of 
the bark of a tree with the resin in situ , together with fruits of the same plant, and 
