112 



MASON— ACTION OF WATER UPON METALS. 



[April 19, 



To quote Dr. Snmmerville in his recent paper in Water: 

 " Lead to the extent of . 25 part per milHon is sufficient to condemn 

 a potable water." 



That sundry waters contain enough lead to prevent their ac- 

 ceptance by at least some of the standards above laid down is 

 shown by the fact that a few years ago it was reported that sixty- 

 three (6^,) cities of Massachusetts possessed public water supplies 

 which contained lead in amounts varying from 85.46 to .023 per 

 million. In four of these cities where lead poisoning was pro- 

 nounced the average amount of the metal present during ordinary 

 daytime use was one part or over per million. Occasional instances 

 of " plumbism " were noticed in other towns and doubtless mild 

 or unrecognized cases occurred elsewhere.^ 



In the 31st annual report of the London local Government 

 Board (1901 and 1902 Supplement on Lead Poisoning and Water 

 Supply, Vol. 2, page 426), peaty moorland waters are shown to 

 be especially plumbo-solvent, to a degree chiefly governed by the 

 amount of acidity present, and experiments show that such acidity 

 is due, at least in part, to acid-forming bacteria residing in the peat. 



For instance, the influence of acidity is shown by the action of 

 the following moorland waters from Lancashire and Yorkshire : - 



Acidity of water in terms of c c of N/io 



Na2Co3 required to neutralize loo 



c.c. of the water. 



0.2 



•3 



•4 



•5 



.6 



.8 



.9 

 I.I 

 2.2 



Milligrams of Pb. in loo c.c. of the 

 water after filtering through 

 lead shot. 



.28 



.25 



•4 



.66 



.92 



1.5 

 2.4 

 3-2 

 8.6 



The London report already quoted is so firm in its belief that 

 the cause of plumbo-solvency has been located that it ventures to 

 rate moorland waters as " safe " if they are neutral to lacmoid and 

 as " dangerous " if they react acid with that indicator. Attention 



^ Mass. State Board of Health, 1898, p. 543. 

 " Thresh, " Examination of Water," p. 186. 



