, both at home and abroad, it proved exceedingly remunerative.
Extensive works for the application of the process were erected at
Landore, where Siemens prosecuted his experiments on the subject with
unfailing ardour, and, among other things, succeeded in making a basic
brick for the lining of his furnaces which withstood the intense heat
fairly well.

The process in detail consists in freeing the bath of melted pig-iron
from excess of carbon by adding broken lumps of pure hematite or
magnetite iron ore. This causes a violent boiling, which is kept up
until the metal becomes soft enough, when it is allowed to stand to let
the metal clear from the slag which floats in scum upon the top. The
separation of the slag and iron is facilitated by throwing in some lime
from time to time. Spiegel, or specular iron, is then added; about 1 per
cent. more than in the scrap process. From 20 to 24 cwt. of ore are used
in a 5-ton charge, and about half the metal is reduced and turned into
steel, so that the yield in ingots is from 1 to 2 per cent. more than
the weight of pig and spiegel iron in the charge. The consumption of
coal is rather larger than in the scrap process, and is from 14 to 15
cwt. per ton of steel. The two processes of Siemens and Martin are often
combined, both scrap and ore being used in the same charge, the latter
being valuable as a tempering material.

At present there are several large works engaged in manufacturing the
Siemens-Martin steel in England, namely, the Landore, the Parkhead
Forge, those of the Steel Company of Scotland, of Messrs. Vickers & Co.,
Sheffield, and others. These produced no less than 340,000 tons of steel
during the year 1881, and two years later the total output had risen to
half a million tons. In 1876 the British Admiralty built two iron-clads,
the Mercury and Iris, of Siemens-Martin steel, and the experiment
proved so satisfactory, that this material only is now used in the Royal
dockyards for the construction of hulls and boilers. Moreover, the use
of it is gradually extending in the mercantile marine. Contemporaneous
with his development of the open-hearth process, William Siemens
introduced the rotary furnace for producing wrought-iron direct from the
ore without the need of puddling.

The fervent heat of the Siemens furnace led the inventor to devise a
novel means of measuring high temperatures, which illustrates the value
of a broad scientific training to the inventor, and the