ANNIVERSARY ADDRESS OF THE PRESIDENT. cCxvll 
of iron. The octahedral crystals obtained, though they scratched 
quartz, did so with difficulty. The results of analysis sufficiently 
accorded with the formula (Cr? O*, Al? O*), (FeO, MgO), which it 
was inferred the analyses of the natural mineral by M. Abich would 
give. 
Experiments, not yet completed, clearly show that silicates, in- 
fusible in our furnaces, may be prepared. Emeralds were obtained 
in crystals by fusing together, and treating in the manner mentioned, 
l. ol 
gr. gr. 
Pounded emerald .... 2°27 (Ural.) 5:00 
Melted boracic acid .. 1°25 2°00 
Oxide of chrommim 3...) 202 2. 2 O05 
The first mixture gave a stony mass, well-melted, the upper surface 
of which was covered by a multitude of small regular hexagonal cry- 
stals. The second compound gave a beautiful green mass, full of 
cavities in which were crystals similar to those found on the surface 
of the first mixture. Chrysolite was also obtained crystallized. 
By employing borax as a solvent, crystallized alumina was pro- 
cured. A mixture was made in the proportion of 4 parts of fused 
borax to 1 of alumina, and to this was added 1 part of oxide of 
chromium, by weight, to 100 parts ofalumima. Numerous transparent 
crystals of a beautiful ruby colour, disseminated through a vitreous 
mass, were the result. By dissolving the vitreous paste in which they 
were included the crystals were isolated, and found completely unat- 
tackable by acids. In form these crystals resembled those of télésie, 
and in their characters are identified with the real rubies and sap- 
phires of mineralogists. 
Seeing the results of his experiments, M. Ebelmen asks if, by adopt- 
ing the method he has pomted out, we may not hope to obtam gems 
of a sufficient size to be valuable as such. His apparatus was small, 
and a few grammes only of the mixtures were employed. He antici- 
pates that by using a greater quantity of the needful substances, and 
effecting the evaporation of the solvent m apparatus of larger dimen- 
sions, kept for a long time at a high temperature, crystals of greater 
size will be formed. 
M. Ebelmen points out that the results of this inquiry, which can, 
as yet, be only considered as in its infancy, may be useful to geologists, 
as showing them that minerals completely infusible in our furnaces 
may be crystallized by aid of a solvent, at temperatures far inferior to 
that of their fusion, and thus we may account for the presence in 
many rocks of minerals associated with others of very different fusi- 
bility. He does not pretend that boracic acid and the borates have 
always been the natural vehicle for the crystallization of such mine- 
rals, though at the same time he remarks on the evolution of boracic 
acid from the earth, brought up at high temperatures by currents of 
gas and steam, pointing to the Lagoni of Tuscany, whence 500,000 
kilogrammes of boracic acid are annually obtained, to the crystallized 
boracic acid found in the crater of Vulcano, and to the lakes in many 
