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owing to their good colour and free working qualities. Many 
of our buildings in which these stones have been used show 
symptoms of decay, especially in the places where long pieces 
of stone have been required, and in mouldings and ornamental 
work. 
In some cases the sulphuric acid in the atmosphere has 
acted on the clay in these stones, and an impure sulphate of 
alumina having been formed, it is w^ashed by rain out of the 
stone, and the grains of silica in the latter soon crumble away. 
In other instances the water percolates down through the 
beds of the stone placed on its end until it reaches their 
bases, and then the frost in winter and the heat in summer 
expands the water and thus forces olf laminse of stone, in 
addition to supplying acids to act on the stone as above- 
named. 
The under ledges of coping stones, although the stone of 
which they are formed is placed in its proper bedding, often 
exhibit evidence of decay. This seems to arise from the 
moisture percolating the stone and finding its way to the 
lower parts, which, owing to their being shaded from the sun, 
are nearly always wet, and thus prepared for the action of 
frost and heat previously alluded to. 
It is surprising to find so small a variety of building stones 
having been used in Manchester as those above noticed, and 
it is to be desired that the architects and builders of our city 
should try other descriptions of stone when they can be had 
at a moderate price. It is difficult to say how the dolomitic 
limestones of the Permian group in Yorkshire, like those of 
Anston, would endure our climate and atmosphere, but so far 
as my experience goes no instances of them are to be found 
in our buildings. By the facilities which railways now afford, 
one might have expected that some of the beautiful syenite of 
Shap containing large crystals of felspar, or the grey syenite 
of Bootle and Ilavenglass, would have made their appearance 
in Manchester, but to my knowledge none of them have been 
