Effects of Cold —Stromnite—a new Mineral. 177 
17. Effects of Cold. 
Dr. Lyman Foot, of the United States’ Army at Platts- 
burgh, writes, “the thermometer has frequently stood here 
during the late winter at from 15° to 17° of Fah. below 0, 
in the morning, and at 10° and 12° below all day. It isamu- 
sing these cold nights to hear the ice on the lake crack ; the 
report is like that of a six pounder, and the ice instantly 
opens to the width of ten or fifteen feet. Whatis the cause 
of it? Does ice contract on cooling below a certain tempera- 
ture’ ‘The snow has been here four and five feet deep.” 
Remark.—Although in the act of congealing, and for 
eight or ten degrees above freezing, cooling water expands, 
there can be no doubt that when ice is once formed, it con- 
tracts by cold like other bodies. Hence the cracks and re- 
ports, always perceived even on narrow rivers, and on small 
lakes, during the prevalence of intense cold.* When this 
gradual contraction extends over a great surface, as on lake 
Champlain, we might well expect that the accumulated ef- 
fect would produce very loud explosions, and very wide 
fissures ; so wide as occasionally to swallow up, instantly, the 
unwary travellers who, with sleighs and horses, adventure by » 
night, and sometimes even by day, upon the smocth surface 
of our great northern lakes. When the weather grows warm 
again before the ice melts, the fissures close and sometimes 
even overlap, owing obviously to expansion.—Ed. 
18. Stromnite—a new Mineral. 
From Dr. Th. S. Traill of Liverpocl, we have received 
a printed paper read by him before the Royal Society of 
Edinburgh, April 20,1817. It contains an able report of 
ihe characters &c. and composition, of a new mineral from 
Orkney, to which Dr. Traill has given the name of Strom- 
nite. This mineral consists according to Dr. Traill’s anal- 
ysis, of carbonate of strontites 68-6—sulphate of barytes 27°5 
—carbonate of lime 2°6—oxid of iron 0°1=98°8 and the 
loss, of 1-2, in the 109, is attributed to water. 
* These cracks are not to be confounded with those which, during the 
congeiation, proceed from the opposite cause—namely, expansion ; the space 
between the banks of rivers, small lakes, &c. not being wide enough to ad- 
mit the expansion which the water suffers in freezing ; the ice resisted by 
the shores necessarily cracks, and sometimes even cracks and overlaps. 
Vow 1h...No, 4. oF, 
