a7id the Constituents of Well- and River-waters. 57 



2nd. A gallon of water with one ounce of iron wire for two 

 hours gave, — 



Solid residue 16'6936 grs. 



Including matter volatile on ignition. 1*1704 „ 



3rd. A gallon of water with eight ounces of iron wire for two 

 hours gave, — 



Solid residue 13-1824 grs. 



Matter volatile on ignition .... 0"9548 „ 



At the time these experiments were made (January 9, 1857), 

 the water was somewhat discoloured ; and as it evidently varied 

 daily in composition, it appeared necessary, in order to ascertain 

 the actual effects of the iron, to determine at the same time the 

 solid residue and organic matter existing in the water when the 

 above three experiments were made. 



Two separate determinations were made (one gallon for each). 



I. Total solid residue 21-4522 grs. 



Including matter volatile on ignition. 3-2494 „ 



II.* Total solid residue 20-3742 „ 



Including matter volatile on ignition. 2-7566 „ 



Giving a mean of — 



Total solid residue 20-9132 „ 



Matter volatile on ignition .... 3-0020 „ 



From these determinations it is clearly shown that one gallon 

 Thames water, by contact with half an ounce of iron wire for two 

 hours, lost, — 



Mineral matter . . . 3-5420 grs. 



Volatile matter . . . 1*7700 „ 



By contact with one ounce of iron wire for two hours, it lost — 



Mineral constituents . . 4-2196 grs. 

 Volatile matter . . . 1-8316 „ 



By contact with eight ounces of iron wire for two hours, it lost — 



Mineral matter . . . 7-7308 grs. 

 Volatile matter . . . 2-0472 „ 



When the residue which is loft on evaporating Thames water 

 is ignited in a ])latinum dish, I have noticed that the reniains of 

 the organic matter mixed with the bulk of the residue at the 

 bottom of the dish burn off in a few seconds, while at the sides 



* Wlicii the vvatur for this analysis was drawn, a fresh su])])!)' was enter- 

 ing the cisterii8 fruui the mains. 



