TRANSACTIONS OF THK SECTIONS. 65 



equality of ■cast iron. In the last two operations the Blinall quantity of 

 earthy matter in the ore will appear in the form of a clear glass with a 

 slight purple tinge. 



Mr. Mushet described the process of smelting iron ores in the blast 

 furnace as of a twofold nature, and stated that it exhibited all the phe- 

 nomena now alluded to (namely de-oxydation and carburation) ; crude or 

 cast iron when run from the blast furnace must have passed through 

 the various stages of malleable iron and steel before absorbing as much 

 carbon from the fuel as would enable the iron to flow from the furnace. 

 In the upper region of the blast furnace the first operation that takes 

 place towards a perfect reduction is the gradual de-oxydation of the 

 iron ore by the heated fuel in the absence, or nearly so, of oxygen. When 

 this is perfected the particles are in the state of soft or malleable iron, 

 but owing to the short time they are exposed, and the inferior tempe- 

 rature, they are not welded together as in the specimens which were 

 exhibited. As the ore, however, descends in the furnace and meets 

 with a higher temperature and an enlarged volume of fuel, an affinity 

 is established between it and the particles of iron, which by absorb- 

 ing about fnjth of their weight pass into the steely state. A further de- 

 scent in the furnace towards its greatest diameter brings the iron in the 

 state of crude steel into a still higher temperature and in contact M'ith 

 a larger body of fuel, in consequence of which a more powerful affinity 

 is exerted, and the iron finally separated in the state of cast iron, more 

 or less a carburet as the purposes of the manufacturer may require. 



In reference to the protracted process of de-oxydation first alluded to, 

 Mr. Muschet stated that a higher temperature, although required to weld 

 and compact together the particles of iron, was not necessary for the 

 de-oxydation itself, for at a bright red heat all but the very last portions 

 of oxygen may be attracted from the iron, and the pieces of ore left easy 

 to be pulverized. He had at one time taken advantage of this cir- 

 cumstance to form from the iron ore a powerful metalhc cement calcu- 

 lated to give stabiUty to great national undertakings, such as the Ply- 

 mouth Breakwater, Lighthouses, &c. He presented specimens of it 

 resembling masses of iron at a meeting of the Society of Civil Engi- 

 neers, with which that intelligent body (the late Mr. Telford then at 

 their head) expressed themselves highly pleased. But without reference 

 to its merits, as soon as it was known that it could not be rendered as 

 cheap as Roman cement, it ceased to excite any interest and was never 

 inquired after. Sir John Rennie however saw its value, and was anxious 

 to introduce it at the Plymouth Breakwater and at other places, and 

 took a great deal of trouble in the matter. Three or four casks were 

 sent to the Breakwater and there misapplied, as an unfavourable report 

 reached the Admiralty sometime afterwards. This singular cement dif- 

 fers from all others, inasmuch as it expands in the act of setting, by 

 which means it never shrinks from the substance to which it is at- 

 tached, but becomes completely united with it. The West India 

 Dock Company alone seem to appreciate its peculiar properties. They 

 find that it binds together their granite pavement in a way superior to 

 everything else. (The manufacture of it has been discontinued), 



VOL. v.— 183G. K 



