274 THE RING OF NATURE 



on steel, on apparently pure quartz, and in the 

 best sterilized medium that man can prepare. 

 The glass in the Abbey windows that has delighted 

 twenty generations with the beauty of its colours 

 is at last afflicted with ' glass disease.' The colour 

 and the transparency are leaving it, so that in the 

 last stage of the disease it has scarcely any of the 

 properties of glass. Minute holes are drilled through 

 it, and a pressure of the finger produces final 

 dissolution. The patient fungus biding its centuries 

 has overcome even the hard and polished and 

 generally considered impervious glass. 



