384 BULLETIN OF THE NEW YORK STATE MUSEUM 



.00000568 inch per foot, per degree F.; that of sandstone, 

 .000009532 inch per foot, per degree F. For example a 

 sandstone block, ten feet long, would in the change from 

 30^ below zero to 100^ F. above zero, be lengthened .15 of 

 an inch. The mere alteration in volume might not alone 

 work serious injury, but aided by moisture it becomes a 

 most active agent, and the effects of expansion and of water 

 cannot be well disassociated and defined in quantity. The 

 force exerted by freezing water is well known, and a common 

 phenomenon in breaking the strongest material. An ele- 

 mentary example may be cited here — the bursting of quartz- 

 crystals which contain liquid inclusions — or, as commonly 

 stated, bubbles of water. At quarries where porous stones 

 are raised, and particularly sandstones, the practice of 

 *' seasoning" the stone, that is, of letting the moisture in it 

 — " quarry water" — dry out before use, is another common 

 example, illustrating the influence of frost. Cases where 

 unseasoned or ''green" stones have been suddenly cracked 

 and shattered badly, in cold weather, are too common to 

 cite them. 



Applying these generalizations to the several classes of 

 building stone, it may be stated that the effects of frost are 

 exerted along the weaker lines, and hence stones which have 

 a laminated, schistose structure are the most liable to be 

 affected. The scaling or exfoliation, so common in some of 

 our sandstones, is due in great part, to the force of freezing 

 water, and it is most apparent where the conditions favor the 

 ingress of the water and where the position, also, allows of a 

 movement of the outer film or layer — scaling, as in the stones 

 set on edge in an outer wall — the frost acts as a wedge, 

 splitting the stone. Results, as serious, are seen in the gran- 

 ular rocks, whose binding material is readily soluble. The 

 dissolving and disruptive forces of water here unite and, to 

 some extent, the mechanical or abrading force also. Some 

 of the Nova Scotia sandstones in New York city are badly 

 weathered in this way. The worst sufferer from the effect 



