SCIENTIFIC SUMMARY. 
333 
of a special physical property be required, it would be as well to try that 
alloy the composition of which would correspond to the turning-point of the 
curve representing the electric conducting power of the alloys of the two 
metals. 
Artificial Gems. — The Chemical News states that the base of these gems, 
as patented by the superintendent of the Royal Porcelain Works at Berlin, 
is a flux obtained by melting together 6 drachms of carbonate of soda, 
2 drachms burnt borax, 1 drachm saltpetre, 3 drachms minium, and 11- 
ounces of purest white sand. To imitate in colour, but of course not in com- 
position, the following minerals, add to the flux the ingredients named in 
connection with each gem : — Sapphire., 10 grains carbonate of cobalt. — 
Opal, 10 grains oxide of cobalt, 15 grains oxide of manganese, and from 
20 to 30 grains protoxide of iron. — Amethyst, 4 to 5 grains carbonate of 
peroxide of manganese. — Gold Topaz, 30 grains of oxide of uranium, — 
Emerald, 20 grains protoxide of iron, and 10 grains carbonate of copper. 
The Chemistry of the Bessemer Process. — In a paper which a contemporary 
has translated from Aus der Natur,” an excellent account is given of the 
examination of iron, as it travels through the several stages of the Bessemer 
process. The description is given under the following heads : — 1. The 
iron taken was dark-grey, graphitic, containing considerable silicon, very 
little phosphorus and sulphur, and much manganese ) in every respect an 
excellent material for the Bessemer process. A small amount of copper 
was present, but not enough to either hinder the process or deteriorate the 
product. — 2. At the close of the first period spoken of, all graphite had dis- 
appeared, partly by combustion, partly by combination with the iron ; almost 
four-fifths of the silicon had been separated ,* all but a trace of sulphur had 
disappeared ; the amount of phosphorus remained nearly the same ; also the 
total amount of the copper, while its percentage was a little higher ; much 
of the manganese was lost. The product at the close of this period was a 
pure white raw iron, containing not overmuch of carbon. — 3. During the 
second period the removal of the carbon progresses rapidly, so also the still 
remaining silicon and manganese are rapidly disappearing, while again the 
copper and phosphorus remain almost the same. The product at the close 
of this period of only about seven minutes was a good steel ', according to 
the common scale, steel No. 3. — 4. At the close of the third period, a steel 
No. 7 was obtained. The addition of 6 cwts. raw iron gave a Bessemer- 
steel No. 6. The slags obtained at the various stages were also analysed ,* 
they always contained a great relative amount of silica, but, both before 
and after the second (or boiling”) period, remarkably little of ferrous 
oxide. During the last stages of the process, the percentage of manganese 
in the slag decreases, because most of the manganese is removed in the first 
period ; so that the increase of slag during the last stages of the process can 
only add iron to it, i.e. reduce the percentage of the manganese. A little 
alumina and lime found in the slag is ascribed to the walls of the furnace. 
VOL. VII. — NO. XXVIII. 
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