172 
POPULAR SCIENCE REVIEW. 
once more disappointed. It is remarkable that nearly twenty years have gone 
by since a great comet was visible in the northern hemisphere, the only 
approach to one being Coggia’s Comet, which was visible to the naked eye 
as a bright comet for several nights during the early summer of 1876. 
From the description of this great Southern comet which has been received 
from the Cape of Good Hope and from St. Helena, it would seem to ha\ r e 
been remarkable for the great length and brilliancy of its tail, which extended 
over the heavens for nearly 90°. The nucleus seems to have been inconsider- 
able. The comet seems to have moved in an orbit greatly inclined to the 
ecliptic, and to have passed its perihelion in the latter part of January, 
sweeping round in an orbit very close to the Sun. It carried its tail in such 
a manner that it lay almost parallel to the plane of our horizon, so that, 
though very vivid in the southern hemisphere in those latitudes, the tail 
must have been nearly parallel to the plane of the horizon, and so have been 
buried in the mists inseparable in the spring from a low altitude. 
BOTANY. 
The plants used in making Curare. — M. G. Planchon finds that four 
different species of Strychnos constitute the true basis of the poison known 
under the name of curare or urari, as made and used in four different regions 
of South America. In British Guiana, as Sehomburgk ascertained, the 
principal ingredient of the curare made by the Macusis Indians, is the 
species described by him under the name of Strychnos toxifera, which, 
however, is associated with two other species, S. Schomhurgkii and S. cogens. 
In the Upper- Amazons region the Pebas Indians prepare their arrow-poison 
from a species described by Weddell as S. Castelnceana, in honour of M. de 
Castelnau, who obtained it during his South American travels. It is usually 
associated with a species of Cocculus (C. toxicofeius, Wedd.). From the 
region of the Rio Negro, the roots, stems, and leaves of the plant used, were 
sent to Paris at the time of the Exposition of 1878 ; it proved to be an 
unknown species, and was described by M. Planchon under the name of 
Strychnos Gubleri. Lastly, the Roucouyenne and Trios Indians of Upper 
French Guiana employ a species described by M. Planchon as Strychnos 
Crevauxii, in honour of M. Crdvaux, who lately brought specimens to 
Europe. lie states that on the banks of the Parou, an affluent of the 
Lower Amazons, this plant bears the name of ourari or urari , although it 
is quite distinct from the species so named elsewhere. (Comptes JRendus, 
January 19, 1880.) 
CHEMISTRY. 
The Artificial Production of Manganese Bioxide. — By long-continued and 
constant heating of manganese nitrate in a flask, in an oil-bath or paraffin- 
bath at 155° to 162°, Gorgeu (Compt.Rend., 1879, 796) succeeded in obtaining 
