570 
POPULAR SCIENCE REVIEW. 
METALLURGY. 
Plumbago Crucibles are made of graphite, mixed with a certain amount of 
clay to render it plastic. Some that are now manufactured are capable of 
melting on an average forty pourings of the most difficult metals, and a 
still greater number of those of an ordinary character. They are unaffected 
by change of temperature, seldom crack, and are very durable. Crucibles 
of this kind are now adapted for malleable iron melting, and for zinc 
melting. 
Examination of Cast Iron . — When melted pig-iron is tapped into a ladle 
in moderate quantities, and allowed to stand a few minutes until it becomes 
perfectly quiet, and then carefully skimmed clean, a beautiful iridescence 
covers its entire surface, due to the constant breaking up of the extremely 
thin film of oxide formed on the iron. On close inspection, the coating is 
found to consist of a multitude of many-rayed stars in constant motion, 
breaking up and re-forming with great rapidity. It has lately been sug- 
gested that, as the size of the different figures is believed to depend on the 
size of the grain of iron when in the pig, the nature of the former will 
give an indication of the quality of the iron ; and if instantaneous photo- 
graphs were taken, they might possibly throw light on the phenomena of 
the crystallization of iron on cooling and the laws regulating it, about 
which we require much more information than we possess. 
Iron reduced by Peat. — Mr. T. Vincent Lee, C.E., gives some particulars 
regarding this new application of peat. He took specimens of iron so 
reduced to the Dublin Exhibition, and it was declared by many of the best 
judges to be equal to Swedish. The quantity of properly prepared peat 
per ton of iron is about 1 ton, 15 cwt., the cost being slightly in favour of 
coal or coke ; but the price of the iron made by peat is from £2 to £3 per 
ton above that from coke or coal. Prepared peat will also, he says, gene- 
rate and maintain steam quicker and better than either coal or coke ; and 
machinery is now being made in London to produce it. 
Action of Wolfram on Cast Iron. — M. le Guen has made experiments on 
this subject at the military post of Brest, and finds that cast iron composed 
of old and new iron, combined in the proportions forgiving greatest strength, 
is made much stronger by the addition of less than 2 per cent, of wolfram. 
In one case, after two fusions, the resistance to fracture was increased by 
more than a third. The superiority was maintained after several fusions ; 
and the cast iron so treated was also rendered tougher and more elastic. 
The wolfram is easily added, merely requiring to be pulverized without 
previous reduction. 
The Action of Manganese in Iron Smelting . — Captain Caron, in con- 
tinuing his researches on steel, has applied himself to the effects of man- 
ganese in iron ore. He remarks that nearly all good samples of steel come 
from ores containing much manganese, and it has long been observed that 
its presence is almost indispensable for the production of superior steel. 
The results of his experiments he sums up thus : — By the addition of a 
suitable quantity of metallic manganese sulphur is removed even without 
refining ; silicon is in great part removed on refining ; whilst phosphorus 
resists its action altogether. These observations are confirmed by experi- 
