Royal Academy of Sciences at Paris. - 145 
of the charcoal left in the fabrication of Prussian blue. This’ 
charcoal, when it has been prepared, possesses qualities infinitely 
superior to those of charcoal produced from bones, and it is known 
that it is furnished by other animal matters than bones, and is 
prepared by potash. 
In the charcoal residue of Prussian blue, the whole, or nearly 
the whole, is charcoal ; while in the charcoal from bones, there 
is scarcely more than a fifth of pure charcoal ; the other four- 
fifths are formed of phosphate and carbonate of lime, matters 
altogether foreign to the action of charcoal, 
From these considerations, the Society proposes a prize of. 
two thousand franes to the person who shall communicate a cer- 
tain and ceconomical process for converting animal matters, other 
than bones, into a charcoal possessing all the qualities of chars 
coal from bones. The price of the charcoal thus obtained must 
not be greater than the present price of charcoal from bones (ten 
centimes the pound). 
For the fabrication of isinglass, 
The Society offers a prize of two thousand franes to the per- 
son who will establish in France a manufacture of isinglass, of a 
quality which may stand competition with the isinglass of the: 
north. To be awarded in July 1819. 
(Economical Arts. 
For the discovery of avegetable substance, either natural or pre= 
pared, which will serve as a complete substitute for the leaves 
of the mulberry in the rearing of silk-worms, 
A prize of two thousand francs. 
ROYAL ACADEMY OF SCIENCES AT PARIS. 
At a meeting of the Academy on the30th of March last, M. Des= 
fontaines made a report on a memoir by M. Delile, on that 
long sought for tree of ancient times, the Persea. It was fora 
merly, as we learn from the descriptions of Pliny, Theophrastus, 
and Dioscorides, much cultivated in Egypt on account of an ex- 
cellent fruit which it yielded ; but for ages past it has wholly dis- 
appeared from the banks of the Nile. M. Dellile thinks, however, 
that he has now recognised it in the Xymenia Egyptiaca of Lin« 
neeus, one specimen of which he saw in a garden at Cairo, and 
two others in Upper Egypt ; and it appears also from his res’ 
searches, that it abounds in Nubia and Abyssinia, under the 
name of the glig. The tree as described by Theophrastus ¢ req 
sembles the pear-tree; but differs from it in being evergreen, It 
produces fruits in abundance, which ripen about the time of the 
Etesian winds. When the fruit is intended to be kept, it is ga- 
Vol. 52, No, 244, Aug. 1818, K thered 
