Mr. Napier on Sandstones used for Building. 321 



Being an average of nearly one gaUon and a quarter of water per cubic 

 foot of stone. 



The time necessary for the water to rise up from the foundation by 

 capillary attraction is, however, considerable. And it varies much with 

 different qualities of stone, depending a good deal upon the physical 

 structure of the stone. I have witnessed the water rising up one 

 portion of a stone in less than half the time it did in another portion 

 of the same stone, and these different parts by testing give no chemical 

 d^erence Taking a 6-inch cube, the following rate is an average of 

 that I obtained; the lower part of the stone was merely aUowed to 

 ^ouch the water and did not dip into it above an eighth part of an inch. 



1 minute to the 1st inch, it required, 



3 — 2d _ 



6 - 3d - 



10 — 4th _ 



20 — 6th _ 



35 — 6th. 



75 minutes to rise 6 inches. 



This is no doubt a slow rate when we come to several feet, still from a 

 damp found it is certain, and the only limit to it is when the evaporation 

 from the surface is equal to the supply by absorption, and this in damp 

 weather takes it often above one storey of a building; it is no doubt 

 increased by the absorption from the weather outside, and this often to 

 such an extent that I have seen stones inside of a bouse, two storeys up 

 become wet, and literally sweat from the water filtering through them 

 VVo believe the only preventive yet tried for the capillary attraction 

 nsmg from the found, is a layer of Caithness slate; common slate I have 

 lound equal, if not superior, to Caithness, and cheaper; but which- 

 ever be used it ought to be laid above the surface of the ground, other- 

 wise the use of such precautions is neutralised. 

 Vol. III.— No. 5. 6 



