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the lime and forming sulphate of lime, whilst the carbonic 
acid once united to it went to the iron and formed carbon- 
ate of iron. He was not acquainted with the composition 
of the mud dredged out of the Suez Canal, and therefore 
could not speak with certainty, hut probably the selenite 
was formed by a somewhat similar double decomposition to 
that last described. 
Mr. BROCKBANK, F.G.S., exhibited a specimen of mineral 
wool, produced at the Conshohocken Iron Works, in America, 
by passing a steam jet through a stream of molten slag in 
its flow from the blast furnace. It had a lustrous white 
fibre, singularly like cotton wool from the pod. It can be 
made at a very trifling cost, and is likely to come into use 
for several purposes. It is said to be a very effectual non- 
conductor of heat, and this has led to its being used in the 
United States for the coating of steam boilers and for the 
linings of refrigerators. Similar mineral wool is sometimes 
produced during the blowing in the Bessemer steel con- 
verters, but only in small quantities. 
Mr. Brockbank also described a very simple mode of 
utilising slag, adopted at the George-Maria-Hiitte Blast 
Furnaces, at Osnabriick, in Hanover. The molten slag is 
allowed to fall in a stream, from a height of about eight feet, 
into water, and is thus formed into large bean-shaped gravel. 
From the water tank it is lifted into railway trucks by 
“Jacob’s ladders,” and is conveyed away as fast as it is 
produced, and largely used for metalling railways. 
In some of the English iron works the slag is now being 
broken up by Blakes’ stonebreakers, and sold for metalling 
roads ; — and in this way it proves a source of profit, instead 
of being a considerable loss in its usual form of huge heaps 
of slag, disfiguring the country. 
The Bessemer slags of the Hematite furnaces are found 
to make excellent concrete, on account of the large quantity 
