Chemistry and Physics. 255 
hydrate ; pyrites, from the formationsof a hydrate of iron; copper py- 
rites and variegated pyrites, probably from the same, the latter being 
very jotiiercabia for the rapidity with which the change takes sarge in 
a moist atmosphere ; antimony —— and other antimony o rom 
the formation of antimony ochre; fahlerz, and other menial ores, 
probably from the oxydation of he arsenic. 
These irised colors sometimes proceed from the absorption of oxy- 
gen and the elimination of water, or from a disengagement of carbonic 
acid with a loss of water, as in spathic iron and carbonate of manganese. 
rc is often favored by heating, as in the case of = = 
he Radiating Power of Substances; by A. Masson and L. 
desncazia, (Comptes Rendus, Dec. 20, 1847.)—In the hen of 
Masson and Courtépée, the substances, pulverized with some water hold- 
cube of copper. This cube filled with boiling water was placed before 
a thermo- a pile, x a the radiating surfaces perpendicular to its 
axis. ey conclude 
1. The cmniaie have a das _aaiested radiating power when in grains, 
than when melted or in mass 
2. That the radiating power of a sera depends on the cohesion 
of Pe — and not upon their natu 
. That if all bodies were bie’ to the same degree of chemical 
sabdivision, taty would have at 100° C., the same radiating power. 
On Auriferous Glass ; by H. Ross, (Pogg. Annal., Ixxii, 556.) — 
Gold is well known to'be used in making a beautiful red glass. After 
fusion this glass is colorless; but when heated not above a red heat, it 
becomes of a bright red color. Rose suggests that the paid: is contain- 
ed in the glass in the state of a protoxyd, which forms a colorless sili- 
cate by fusion, but sets free some portion of the protoxyd when ea 
ed to a temperature a little below that which forms it. This protoxyd 
disseminated in a small mph = in an extreme state of sisbdleieton, is 
believed to give the red color. When too much heated the red changes 
to a brown, and Rose een this to the oxyd of gold becoming partly 
reduced and metallic gold set free. A fact, according to Rose, con- 
firming this view, is presente d ‘i copper. Fora glass containing the 
of borax, 12 of n yl of minium, and 1 of arsenous acid; these are 
moistened with a soletiee of 8 dada of gold in aqua regia, and then 
8. Dim orphism of Zinc, (Jour. Pharm. et Chem., xiii, 18.)—Neg- 
garath has described (Annales de Pogg., xxxix, 324) crystals of pure 
pre “om ed form of hexagonal prisms. J. Nicklés reports that a ~ 
oc prepared by M. Favre, after Jacquelain’s process, w 
crystallized in pentagonal dodecahedrons, like those of pyrites and gray 
ine is therefore dimorphous. ‘This is not the only example 
in erie prisms (dimetric system), sr Frankenheim has observed it in 
cubes osé (Annales de Pogg., xlv, 319) has announced that pal- 
tedium and iridium are iesdicnseptanens pone both in the rhombo- 
hedral and tesseral systems. 
Mii Mia 
