Disturbance of the Earth’s Magnetism. 143 
Chlorovinite of lime is in the form of hexagonal prisms, generally 
truncated, but sometimes pyramidically terminated: colorless and 
transparent, brittle, cross fracture even, permanent in the atmosphere 
and unaltered by light. In dry air the crystals become opake and 
finally fall to powder; warmed, they give off pure water; heated, they 
swell, emit gas, char and at near the temperature of melting glass, a 
gray fused mass, composed of chloride of calcium, carbonate of lime 
and carbon remains. In pure alcohol, they lose water and slowly dis- 
solve; a hot saturated solution, deposits crystals on cooling. In water 
it is very soluble; its solution dissolves much salt when heated and de- 
posits crystals on cooling. Its solution when added to a solution of 
nitrate of silver, causes the precipitation of dense curdy white flocks; 
in nitrate of lead, no precipitate, or cloudiness appears, even if the 
solutions are concentrated, or heated; with pro-nitrate of mercury, 
there is a white precipitate which becomes crystalline, and is partially 
soluble in water. With solutions of copper, chlorides of sodium, ba- 
rium and potassium, the resulting salts are soluble. Oxalic acid 
eliminates the acid and forms a white oxalate of lime. 
(To be continued.) 
Art. XVI.—On a disturbance of the Earth's magnetism, in con- 
nexion with the appearance of an Aurora Borealis, as observed at 
Albany, April 19th, 1881; by JosrpH Henry, of the Albany 
Academy. 
[Communicated to the Albany Institute,* January 26, 1832.] 
Tuar the aurora has some connexion with the magnetism of the 
earth, was asserted as early as the middle of the last century ; and 
since that time, many observations have been recorded, tending to 
confirm this position. 1. It has been observed, that when the au- 
rora appears near the northern horizon in the form of an arch, the 
middle of this is not in the direction of the true north, but in that 
of the magnetic needle at the place of observation; and that when 
the arch rises towards the zenith, it constantly crosses the heavens 
at right angles, not to the true, but to the magnetic meridian. ‘This 
fact is most obvious where the variation of the needle is great. 
* And forwarded for insertion in this Journal. 
