Intelligence and Miscellaneous Articles. 397 
denotes a small weight (such as is usually supplied with the appa- 
ratus by the makers), the extent of the oscillation becomes insen- 
sible. This formula, applied to the apparatus with which the ex- 
periments were made, gives the theoretical maximum of ¢ about 
18 minutes of a degree. It is evident that when F represents a 
weight, it should be replaced in the differential equation by F cos 4, 
but the result practically coincides with that actually obtained when 
F is not excessive. 
That these oscillations must exist will be evident, when it is con- 
sidered that the gyroscope, with the weight attached and the disc 
not spinning, becomes an ordinary pendulum: the effect of the 
spinning being to disturb its oscillations, and to lessen their extent 
to an unlimited amount, whenever the spinning of the disc is suffi- 
ciently rapid. 
The preceding investigations, as well as the experiments, show 
that whenever a force is applied to the axis of a revolving disc, more 
or less of the momentum due to this force is converted into a mo- 
mentum of rotation parallel to a plane which is perpendicular to 
that in which the force acts. 
XLVI. Intelligence and Miscellaneous Articles. 
ON DEMIDOVITE, A NEW SPECIES OF MINERAL FROM NIJNE 
TAGUIL IN THE URAL. BY N. NORDENSKIOLD. 
For some years there has been brought from Taguil* a mineral 
which occurs but rarely, and to which the name of blue malachite has 
been givenon the spot. The name cannot by any means be applied 
to the mineral in question, as it contains no traces of carbonate of 
copper, although it is found in thin layers with malachite. This 
mineral possessing, as will be seen hereafter, a new and very inter- 
esting composition, I venture to propose giving it the name of Demi- 
dovite, as a permanent homage to His Excellency M. Anatole de 
Demidov, who has so powerfully contributed to the advancement of 
mineralogy and geology by his munificence and his scientific travels. 
* These works belong to Prince Anatole Demidoff, and to his nephew 
Paul Demidoff. They lie 150 wersts (about 100 English miles) to the 
north of Ekatermenburg, on the east side of the frontier between Asia and 
Europe, but one part of the property is also on the European side. 
The yearly produce amounts to more than 1,000,000 pud + of iron (the bar 
iron from there is known in this country under the name of old Sobel 
iron) ; nearly 240,000 pud of copper; and about 50 pud of native platina 
and 25 pud of gold is yearly washed from the sand. The platinum is only 
found on the Kuropean side of the Ural Mountains, but gold on both 
sides, although for the most part on the east, or Asiatic side. A great 
deal of the iron and copper goes directly to Asia. 
The forests whence the charcoal is derived are very extensive, and give, 
when sixty years are allowed for their renovation, 275,000 korob of charcoal 
yearly, every korob containing 70} cubic English feet. 
The proprietors avail themselves of every new discovery in mining and 
metallurgy, and have in their employment natives of nearly every country 
of Europe,—England, France, Germany, Sweden and Finland. 
+ The pud is somewhat less than 40 lbs. 
