SCIENTIFIC SUMMARY. 
509 
removed. In connexion with this, Mr. Foster remarked that in some of the 
fragments of elvan in the mines the crystals of felspar have been gradually 
removed, and replaced by chlorite ; in fact, “ they had psendomorphs in 
process of formation.” Among other curious phenomena in this mine, were 
the so-called caps ; some of the chlorite having formed over the crystals of 
quartz, over the first other secondary layers were formed, and these easily 
separated from each other, thus giving rise to the term “ caps.” Mr. Foster’s 
observations of some of the fissures in the mine lead him to conclude that 
the various deposits had been introduced at different periods. 
Black Spindle. — This mineral forms the subject of a memoir by M. Pisani. 
It forms one of the constituents of the cherzolite of Auvergne, and presents 
itself generally in the form of simple octohedra, being occasionally, however, 
of a pyramidal shape. It is infusible, of great hardness, and takes an 
excellent polish, and is not affected by acid reagents. — Gomptes Rendus , 
July 9th. 
Iron Founding. — The value of the iron made in 1860 in the United States 
was 28^ million dollars, being 8^ millions in excess of the returns for the 
year 1850. 
Hexagonal Blende. — Two papers describing this substance, and especially 
its phosphorescent properties, were presented to the French Academy by 
M. E. Becquerel and M. Sidot. The mode of preparation adopted by the 
latter being to volatilize the natural blende, or artificially prepared amorphous 
sulphide, in a current of pure and dry sulphurous acid. The sulphide is 
placed in a porcelain tube, and is strongly heated for four or five hours, after 
which crystals will be found at the cold end of the tube. M. Becquerel has 
examined the properties of the crystals so produced, and has found them 
phosphorescent in the highest degree after insulation. He remarks that the 
outer crystals in the mass he examined were white, while the inner ones had 
a yellow tint resembling that of uranium compounds, and this yellow tint, 
he thinks, is due to a molecular arrangement, which is the cause of phos- 
phorescence. Yellow crystals are generally phosphorescent. M. Becquerel 
examined the light by the aid of the phosphoroscope, and found that the 
white crystals, with a moderate velocity of the instrument, showed a beau- 
tiful blue light ; the yellow crystals showed a greenish-yellow with the lowest 
velocity, which passed to a blue as the velocity increased, but a blue less 
deep than that furnished by the white crystals, thus indicating a mixture 
of the green with the blue light of shorter duration. The coloured crystals 
thus afford rays of different refrangibility and of unequal duration, like 
diamonds, silicate of lime, and other bodies. It is observed, however, that 
the bodies showing blue light are very few in number. M. Becquerel has 
also studied the effects of the different rays of the spectrum upon hexagonal 
blende, and has found that the maximum of action is between the lines G 
and H, rather nearer G than H. — Vide Gomptes Rendus, July 23rd ; and 
Chemical News, August. 
Old Roman Mines in Spain. — In the mines of San Domingo, in Spain, 
some discoveries of Koman mining implements and galleries have been 
made, which show us the colossal character of the labours undertaken 
by that ancient nation. In some instances, draining galleries nearly three 
miles in length were discovered, and in others, the remains of wheels used 
