144 Chemistry and Chemical Arts. 
rate the sulphur from the sulphuret of sodium ; but on the large scale, 
the protoxide is preferable. In order to procure this oxide, heat 
metallic copper to redness and plunge it into water containing in so- 
lution 0.02 of the nitrate of soda of Chili. The sulphuret of cop- 
per derived from this manufacture, mingled with one sixth of pow- 
dered sulphur, is easily transformed into a sulphate by roasting.— 
Idem. 
20. Preparation of Artificial Ultramarine; by Rostauer. 
(Acad. des Sc., ler. Sept. 1832.)—Introduce into a stone-ware 
retort, luted with clay, a mixture of 1 part of kaolin, 14 parts of sul- 
phur and 14 parts of dry and pure carbonate of soda; then heat 
gradually so long as any vapors are disengaged; leave the retort to 
cool; break it, and there will be found in the interior a spongy mass 
of a very fine green color, but on attracting moisture from the air, it 
passes gradually to blue. Wash the mass; the excess of sulphate 
dissolves, and there remains a very beautiful blue. Wash it by de- 
cantation, dry and calcine it anew in a cherry-red heat in order to 
expel the excess of sulphur. The blue thus prepared, is of a very 
agreeable color, although it lacks the intensity and does not give the 
azure blue reflection of Guimer; but this difference may render it 
desirable to painters in particular sienines ilo 
21. Annual yield of Cementation-Copper of the Rio Tinto Mine 
in Spain.—The first working of this mine dates back to the times 
of the Romans ; the Arabians and the Moors explored them in their 
turn, and demolished all the works when they were driven from the 
province of Seville. The exploration was resumed at the com- 
mencement of the 18th century, but it was not before the year 1787 
that it had acquired that importance which it has maintained to the 
present day, in consequence of the. attempt to extract by cementa- 
tion the copper contained in the vitriolic waters issuing from the an- 
cient works. It would seem that the iron employed in this process 
is furnished, at the present day, exclusively by the forges of Pédro- 
so, which supply, annually, 2,400 quintals for this object. With 
this quantity, it is said, they prepare 1,800 quintals of copper- 
These mines have received a fresh impulse since the province of Se- 
ville has ceased to receive copper from Chili and Peru. Rio Tinto 
supplies entirely, at os * the —— of Seville.—Jtineraire d 
un Voyage en Espagne. des Mines, t. v. p. 216. 
