292 Chronieles of Science. [April, 
carbonate, exhibited in a greater or less degree by all old bronzes, 
and which is well known to antiquaries as patina, is often accom- 
panied by suboxide of copper, occurring usually in small octohedral 
crystals, greatly resembling those of the native mineral. This 
suboxide is generally in immediate contact with the metal, and 
therefore beneath the external coating of carbonate—a disposition 
with which the mineralogist is familiar, as occurring in certain 
specimens from copper lodes, which exhibit a nucleus of native 
copper surrounded by red oxide, and this again by malachite. 
Both the natural and the artificial specimens are commonly supposed 
to have been formed by the action of atmospheric influences on the 
metal, producing first an oxide, and finally a carbonate ; both being 
regarded as products of oxidation. From carefully conducted 
observations on ancient bronzes, the author is enabled to oppose this 
commonly received opinion, and to show that the red oxide of copper, 
so far from being a product of oxidation, is, in truth, a product of 
reduction. By the action of water charged with oxygen, carbonic 
acid, and various salts, there are first formed upon the bronzes 
certain soluble cupreous salts, which afterwards suffer reduction, 
either partially to the condition of suboxide, or completely to that 
of metallic copper. 
Some valuable chemico-mineralogical views are set forth by Dr. 
Streng in an able memoir “ On the Composition of certain Silicates, 
with especial reference to Polymeric Isomorphism” (“ Ueber die 
Zusammensetzung einiger Silicate mit besonderer Beriicksichtigung 
der polymeren Isomorphie”). Without crowding our pages with 
what Dr. Hofmann aptly enough terms the “ Algebra of Chemistry,” 
it would be impossible to explain Dr. Streng’s views. 
The mineral orthite—a silicate of alumina, protoxide of cerium— 
has been recently discovered by Sandberger at Diirrmosbach, near 
Aschaffenburg, in the Spessart.* It occurs im brownish-black 
lustrous granules or crystalline fragments in an anorthic felspar, 
thus presenting another example of the association of cerium-bearing 
minerals with lime-and-soda felspars. 
In the Italian section of the International Exhibition was a 
specimen of “fine siliceous sand,” occurring on the shore of the 
Adriatic, near Pesaro, where it is used for cutting hard stones, 
sawing marble, &c. This sand has been examined by M. Pisani,{ 
who finds it to be garnetiferous. Granules of magnetic iron ore 
having been removed by the magnet, and carbonate of lime dissolved 
out by hydrochloric acid, the residue consists chiefly of rose-coloured 
grains, which are proved by analysis to be true garnet of the 
variety called almandine. 
* ¢Orthit im Spessart” ‘ Wiirzburger Naturwissenschaftliche Zeitschrift, 
6 Band, 1 Heft, p. 43. 
+ ‘Sable granatifere de Pesaro; Thulite de Traversella: Bustamite du Vicentin.’ 
‘Comptes Rendus,’ No. 2, 1866, 
