SCIENTIFIC SUMMARY. 
323 
Finding a Corundum Mine. — In a late number of tbe ‘^Proceedings of 
tbe Academy of Natural Science,” Philadelphia, it is stated that Professor 
Leidy remarked that he had Yisited a corundum mine, recently opened on 
the farm of Mr. George Ball, in the vicinity of Unionville, Chester Co., Pa. 
The accumulation is perhaps the most extraordinary discovered, and its 
extent yet remains unknown. Detached crystals of corundum have often 
been found in the ploughed fields and roadsides of the neighbourhood, and 
also masses or boulders of the same material have been discovered on the 
surface of the ground or buried in the local drift covering the deeper rocks. 
In several instances boulders of nearly pure corundum have been found in 
the locality up to several tons in weight. The corundum, as exposed to 
view at the bottom of a trench, appears as the crest of a large body or vein 
lying between a decomposing gneiss and a white talcose schist. The vein 
appears to extend in a western direction, and towards the east turns at an 
obtuse angle to the north-east. The exposed portion may probably reach 
twenty or more feet, and averages about six feet in depth and five feet in 
thickness at bottom, and is estimated to contain about fifty tons. How 
much further the vein extends west and north-east, and how far it reaches 
in depth and thickness, can only be determined by future mining. It looks 
as if it promised to be the most valuable deposit of corundum ever found. 
A Prize for an Improved Mode of Burning Coal. — The Council of the 
Society of Arts has had placed at its disposal the sum of 500/., by an anony- 
mous person, through Sir W. Bodkin, for encouraging the discovery of 
improved modes of using coal. The Council, on this account, have offered 
the following prizes : — 1. For a new and improved system of grate, suitable 
to existing chimneys as generally constructed, which shall, with the least 
amount of coal, answer best for warming and ventilating a room. — The 
Society’s gold medal and fifty pounds. 2. For a new and improved system 
of grate, suitable to existing chimneys as generally constructed, which shall, 
with the least amount of coal, best answer for cooking food, combined with 
warming and ventilating the room. — The Society’s gold medal and fifty 
pounds. 3. For the best new and improved system of apparatus which 
shall, by means of gas, most efficiently and economically warm and ventilate 
a room. — The Society’s gold medal and fifty pounds. 4. For the best new 
and improved system of apparatus which shall, by means of gas, be best 
adapted for cooking, combined with warming and ventilating the room. — 
The Society’s gold medal and fifty pounds. 5. For any new and improved 
system or arrangement not included in the foregoing, which shall efficiently 
and economically meet domestic requirements. — The Society’s gold medal 
and fifty pounds. 
Tables for the Determination of Minerals. — This excellent work, which is 
a German one, is by Franz Von Kobell, and is published ’ at Munich 
(Miinchen), by Herr J. Lindauer. It is now in its tenth edition, and is 
invaluable to the student of mineralogy. 
Diamonds in Californian Sands. — The “ Chemical News ” of May 30, says 
that Professor Silliman, having received from Mr. Trendwell, of San Fran- 
cisco, a small parcel of the sand resulting from the hydraulic treatment of 
ores, found, on examination with the microscope, that they abounded in fine 
colourless zircons of the form of those of Expailly, along with crystals of 
Y 2 
