116 Scientific Intelligence. 
hour after that passage; a secondary minimum about three hours after 
it; and a secondary maximum about eight hours after it. 
3d. Total Force of the Earth’s Magnetism.—A minimum occurs 
when the sun and moon are in opposition, equal maxima near the 
quadratures, and a secondary minimum at the time of conjunction. 
n the mean diurnal period for the year, 
The principal maximum occurs at 54 40™ p, mu, 
| minimu 0 a.m. 
A secondary maximum ‘“ 7 10-4. M. 
bear he . ‘ 
that passage. Curves were exhibited illustrating these results, and also 
the diurnal motion of a magnetic needle freely suspended in the direc- 
tion of the magnetic force. From the latter some curious results have 
been deduced, which will be found elsewhere. It will be enough to 
mention, at present, that in the mean for the year, the motion from 6 
4. M. till 6 P.M. is very trifling; between midnight and 6 A. wm, the 
needle is almost stationary, nearly the whole motion occurring between 
6 A. M., noon, and 6 P.M 
poses to call yttro-ilmenite, because it is found to contain no tantalic or 
colambic acid, but in its place the oxyd of the new metal.* Ilmenic acid 
| seeninpat se siete the characters of columbic acid, but is distinguished 
y many peculiarities. Bri i ic aci 
columbic acid ; it becomes very y 
ened with hydrochloric acid, acquires a blue color by the contact of zine; 
it expels by fusion with carbonate of soda a much greater proportion of 
carbonic acid. From niobie acid it. is distinguished by the absolute in- 
solubility of its hydrate in concentrated hydrochloric acid, and that it 
does not color the bead of the blowpipe, . + att 
A characteristic reaction of ilmenic acid is that a solution of ilmenate 
of soda with hydrochloric acid, produces with nutgalls or ferrocyanid of 
tassium, brown precipitates much deeper than the hydrate of iron. 
either columbic nor niobie acid gives precipitates of so deep a color. 
Moreover the atomic number of ilmenium is much less than that of colum- 
bium or niobium. If we assume for ilmenic acid two equivalents of oxy- 
gen, the atomic number of ilmenium will be 62-4, (753 = I.) _ = 
__ The metal is obtained by igniting the ammoniacal chlorid of ilmenium 
in an atmosphere of ammonia. It forms a porous mass, or small co- 
herent flakes, with a soot-black color, like the carbon from burnt sugar. 
It does not decompose water; and is unattacked by strong nitric or by- 
* 
ee ete cite 
esl r ae ei 
