350 



Professor Henry E. Armstrong 



[Feb. 19, 



useless after a few months or a year or so. The corrosion does not 

 always take place throughout the whole length of the pipe but more 

 or less locally ; and it has happened in several cases that a water 

 which did not corrode the pipe in a well of considerable depth became 

 corrosive when the bore has been carried to a greater depth. There 

 can be no doubt that corrosion is due to the presence of carbonic acid, 

 tosrether with oxviren, in the water but we shall have to discover why 



Fig. 11. 



pipes behave so differently. It is surprising, considering the great 

 importance of the problem, that no systematic inquiry has ever been 

 promoted by the iron trade. In not a few cases artesian water 

 contains such a proportion of salts that it cannot be used by animals ; 

 and even if it can be so used, in some cases, when applied to the soil, 

 owing to its alkalinity, it causes the soil to cake, so that this becomes 

 waterlogged when flooded. 



