41- Dr. MacCulloch on a Method of Splitting Rocks by Fire. 



Art. VI. — On a Method of Splitting Roclcs by Fire. By 

 John MacCulloch, M. D. F. R. S. F. L. S. and M.G.S. 

 Chemist to the Board of Ordnance, and Professor of Che- 

 mistry in Addiscombe College. Communicated by the 

 Author. 



Many large tracts of the mountainous land of Scotland, 

 which possess an excellent soil capable of cultivation, are in- 

 cumbered by huge alluvial or detached blocks of stone ; and 

 the expense of removing these from the surface forms, in 

 many cases, nearly the whole difficulty which stands in the 

 way of their improvement. Where dikes, or stone-walls are 

 required to enclose such land, the expense of thus clearing 

 the soil is materially diminished by the countervailing value 

 of the quarry which the field itself thus affords. But even 

 in these cases, where the blocks are too large to be weighed 

 and removed entire, a considerable expense is incurred by 

 the necessity of blasting them by gunpowder until they are 

 reduced to a portable dimension. This, however, is the 

 practice almost univez - sally resorted to in Scotland ; and 

 every where, I believe, throughout Britain, where this kind 

 of improvement is carried on. 



In making the Highland roads also, where it is generally 

 necessary to provide a quantity of stone for the masonry re- 

 quired in supporting the lower side of the road, in fortifying 

 the upper bank, and in the construction of drains and bridges, 

 it is usual to have recourse to such blocks, wherever the road 

 itself is not carried through rocks in such a manner as to 

 produce the necessary quantity of materials. In this case 

 also, the process of blasting is adopted, as it necessarily is, 

 whenever solid rocks are to be cut down or levelled. 



This process is both tedious and expensive, but the price, 

 of course, varies with the wages of labour in different places. 

 Where I am writing it is now 2d. per inch, and, according 

 to the dimensions or nature of the rock to be split, the mine 

 varies from eighteen inches to two feet in depth, or, exclu- 

 sive of the expense of gunpowder, the cost of this mine or 

 blast hole will range from 3s. to 4s. It will be a very mode- 

 rate calculation to estimate twelve inches for one mine, or 2s. 



