78 



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, but 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 furnacCo 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 

 linino-s 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-Hutte 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 



