1889-90.] NATURAL HISTORY OF GROUND WATERS. 165 



This also explains the first appearance of organisms in the 500 litre 

 sample, i.e. in lower layers of water. 



Another experiment on the same well contained a large amount of 

 sulphuric carbolic acid mixture (10 litres cone.) with as thorough as pos- 

 sible disturbance of the mud layer. The result was not much better, 

 water sterile for two days, then reappearance of germs with continued 

 presence of carbolic acid. 



The next experiment was on kettle well 2, which was not walled over, 

 but simply closed by a stone which could be lifted. 



May 16. Litre 



May 17th. Stone cover lifted ; mud at bottom 7'83 cm. thick. By 

 means of a stick with heavy T piece at end, the mud was mixed up with 

 water as thoroughly as possible. Then 10 litres cone, sulphuric carbolic 

 acid was poured in, and the contents of well further stirred up, and the 

 water pumped. 



May 18. Germ free. 



May 19. " " 



May 20. 



May 21. Germs appeared first in litre 500. 



He concludes that well was not thoroughly sterilized. 



A second experiment gave similar results, but somewhat sooner reap- 

 pearance of germs, possibly due to sudden rise in temperature. 



It is evident that sterilization in above manner is not practicable, 

 especially as the long continued presence of the carbolic acid in the water 

 prevents its use. 



He therefore endeavored to find the value of lime as a disinfectant for 

 wells, because, ist, its presence in water does not prevent its use. 2nd. It 

 has shown itself especially useful in cases where it was a question of the 

 removal of suspended organic matter. 



June 9th. 10 kgrm lime was shaken up with 4 kgrm water, and the 

 whole poured into well 2. Then the well contents were thoroughly mixed 

 mechanically, and finally the water raised to the top of pump in order to 

 disinfect it also. 



June loth. Sample intensely alkaline. Water for the four following 

 days contained a considerable amount of lime in solution. 



