122 



Mr. Waldie's Investigations connected 

 Table III. 



[No. 2, 



River water of 5th October, 1866, Ebb 

 tide, cleared by a little hydrochloric 

 acid and filtered, 



R. W. of 10th October, Flood, filtered, 



R. W. of 10th Nov. Flood, filtered, ... 



R. W. of 19th Nov. Ebb, Surface, ... 



Deep, 



R. W. 15th Feb. 1867, Flood, 

 Dalhousie Sq. Tank W. of 9th Oct.1866, 



General's Tank, of 6th Feb. 1867, ... 

 Baranagar Tank, of 1st Oct. 1866, ... 

 Ditto, of 15th Feb. 1867, 



Time of trial. 



5th October, 



7th 



10th October, 



12th „ 



10th November, 



12th „ 



19th, \ hour old, 



20th „ 



23rd „ 



19th, \ hour old, 



20th „ 



23rd „ 



15th, 2 hours old, 



16tb, 28 hours-old, 



9th, 3 hours old, 



10th, 16 hours old 



2nd November, 



7th, 3 hours old, 



7th, 26 hours old, 



1st October, 



2nd „ 



15th, 1 hour old, 



16th, 25 hours old, 



Oxygen 



req. for 



100,000 



grs. 



grains. 



.1430 



.0440 

 .1210 

 .0860 

 .1210 

 .0860 

 .1390 

 .0357 

 .0332 

 .0640 

 .0320 

 .0345 

 .1125 

 .0410 

 .1425 

 .0860 

 .0430 

 .2830 

 .1155 

 .3150 

 .2740 

 .4755 

 .3625 



This table exhibits very plainly the rapid diminution of the amount 

 of oxygen required, by keeping even for one clay, and the more gradual 

 diminution afterwards. I have not observed that any notice has been 

 taken of this circumstance by the English chemists. Dr. Macnamara 

 first directed my attention to it, and since then I have not only made 

 many observations of the fact, but have also made experiments as to 

 the cause. The analyses of the London waters published monthly 

 are of the waters supplied by the water companies, therefore, all 

 probably two or three days old. It is evident that in the recent 

 water, there must be substances possessing active deoxidizing properties, 

 which speedily undergo certain changes by which they lose these 



