57(5 FOURTH REPORT— 1834. 



Experiments on the effects of long-continued Heat on Mineral 

 and Organic Substances. By the Rev. William Vernon 

 Harcourt, F.R.S. 



Mr. Havcourt gave an account of the experiments on this sub- 

 ject, which the kindness of the proi)rietors of the Low Moor 

 and Elsecar iron works in Yorkshire, had enabled him to in- 

 stitute. 



The blast furnaces at Low Moor are sometimes regularly 

 worked for twelve years or more ; but the average time for 

 which they continue in action, is from six to seven years. The 

 furnace at Elsecar is usually blown out at the end of three 

 years. During these periods of time the fusion of the iron- 

 stone never ceases in the hearths ; the bottom stone t)f the fur- 

 nace may be considered as constantly kept at the temperature 

 of melting iron, and the hearth-walls in some parts at a still 

 higher heat. When the furnace is blown out, the cooling of so 

 great a mass of masonry is extremely slow. 



The bottom stone, which is about 16 inches thick, is worn 

 away and excavated by degrees, sometimes to more than half 

 its depth, by the action of the iron, so that a pool of metal lies 

 in the hollow, below the level at which the iron is from time to 

 time run oif ; this stone is cracked in various directions by the 

 heat to which it is subjected, and the cracks are filled with 

 veins of melted metal, which occasionally penetrate into the 

 sand on which the stone is laid, and fuse it. 



It is in the metal thus detained within the bottom stone that 

 the segregation of metallic titanium takes place, disseminated 

 in general irregularly through the mass of iron, but where acci- 

 dental vacuities have admitted of its crystallization, foi*ming 

 clusters of cubes. 



On examining with attention the bottom stones of furnaces 

 which had been worked out, Mr. Harcourt observed in them 

 several other species of crystals, some of which appeared to be 

 owing simply to the mutual reaction of the ingredients of 

 the stone itself. The stone is a felspathic grit, and if this ma- 

 terial alone is capable, under these circumstances, of supplying 

 instances of chemical and crystalline rearrangement, it seemed 

 not unreasonable to expect, that by multiplying the means of 

 such rearrangements scope might be afforded for the ap- 

 pearance of numerous interesting phaenomena of a similar de- 

 scription. 



For this purpose, and to forward an undertaking sanctioned by 

 the Association, the Yorkshii'e Philosophical Society, with great 

 liberality, furnished a supply of materials from its museum, and 



