578 FOURTH REPORT — 1834. 



The orifices of the holes were filled to the depth of three or four 

 inches by stoppers made of the gritstone of which the furnace 

 was built. 



The danger in this disposition of the materials is, that 

 a portion of them may be obliterated by the intensity of 

 the heat and the wear of the furnace; but there is reason to 

 expect that enough will remain to show what light is likely to 

 be derived from such experiments, and in what manner they 

 may hereafter be most advantageously conducted. 



The experiments themselves are nearly similar to those which 

 have been before described, the chief difference consisting in a 

 more liberal introduction of crystals, especially of that class 

 which includes water as a constituent part. As examples of the 

 intention with which these were added, it may suffice to notice 

 the selection oinatroUte, a mineral which, if the water it con- 

 tains were expelled, might be expected to pass into sommite ; 

 and of apopliyllite , which in the same case might perhaps re- 

 solve itself into tabular spar and quartz. 



The time at which the Elsecar furnace commenced working, 

 was in October 1833 ; it is probable, therefore, that an exami- 

 nation of the hearth may become practicable before the end 

 of 1836. 



Dr. Clark gave an account and an explanation of the suc- 

 cessful application of the Hot Blast to the j^roduction of Cast 

 Iron. 



In the Clyde iron-works, near Glasgow, during the first six 

 months of the year 1829, every ton of cast iron required for 

 its production 8 tons Ij cwt. of splint coal, reduced to coke, at 

 a loss of 55 per cent. 



During the first six months of the year 1830, after the appli- 

 cation of Mr. Neilson's invention, when the air had been heated 

 to about 300° Fahr., every ton of cast iron required 5 tons 3j 

 cwt. of splint coal, converted into coke. Adding 8 cwt. of coal 

 consumed in heating the air, the saving effected was 2^ tons of 

 splint coal on evei'y ton of cast iron produced. And the same 

 blast was found to be capable of making much more iron, the 

 diminished requisite of air being pretty nearly proportioned to 

 the diminished fuel required. 



But during the first six months of the year 1833, when the 

 temperature of the blast had been raised to above 600°, and 

 when the process of coking the coal had been discovered to be 

 superfluous, and was accordingly omitted, a single ton of cast 

 iron was produced by only 2 tons 5j cwt. of splint coal. Even 

 when we add 8 cwt. of coal to heat the air, the quantity of 



