OF ARTS AND SCIENCES. 67 



" Albany Reservoir Water. — 500 cubic centimetres evaporated to 

 dryness in a platinum capsule over a water-bath gave, of solid residue, 

 0.0924gr, Ignited, the above residue lost 0.0198gr. 



" Cambridge Well-water, that does not act on lead so as to produce 

 known deleterious effects. — 500cc. evaporated to dryness over a water- 

 bath gave, of solid residue, 0.3918gr. ; of which 0.0990gr. were ex- 

 pelled by ignition, and of the non-volatile matters 0.0676gr. were in- 

 soluble in boiling water. 



" Cambridge Well-ioater, that, in an inch-and-a-quarter pipe several 

 years in use dissolves a grain and a half of lead in thirty-six hours. — 

 SOOcc. evaporated to dryness over a water-bath gave, of solid residue, 

 0.1380gr. ; of which 0.0540gr. were expelled by ignition. 



" Cochituate Lake Water. — I. 500cc. evaporated to dryness over 

 a water-bath gave 0.0267gr. of solid residue ; of which 0.0122gr. were 

 expelled by ignition, and O.OOSOgr. of the remainder insoluble in 

 boiling water. — 11. 500cc. over a water-bath gave a solid residue of 

 0.0267gr. 



" Croton River Water. — 500cc. evaporated to dryness over a 

 water-bath gave, of solid residue, 0.2175gr. ; of which 0.l496gr. were 

 expelled by ignition. 



'-'■ Fair mount Water., Schuylkill River. — SOOcc. evaporated to dry- 

 ness over a water-bath gave, of solid residue, 0.3007gr. ; of which 

 0.1032gr. were expelled by ignition, and of the non-volatile matters 

 G.0239gr. were insoluble in boiling water. 



" Jamaica Pond Water. — 500cc. evaporated to dryness over a 

 water-bath gave, of solid residue, 0.026Sgr. ; of which O.OllSgr. were 

 expelled by ignition, and of the non-volatile matters 0.0070gr. were 

 insoluble in boiling water. 



" Troy Reservoir Water. — 500cc. evaporated to dryness over a 

 water-bath gave, of solid residue, 0.0593gr. ; of which O.OlSlgr. were 

 expelled by ignition, and of the non-volatile matters 0.0278gr. were 

 insoluble in boiling water. 



" The above results are expressed in tabular form in Table I. 



" The following tables of results will sufficiently explain themselves. 

 They exhibit quantities of lead which, for practical purposes, have little 

 more than relative value in the columns in which they occur. 



" The experiments were made with bars of lead cast in a common 

 mould, of uniform diameter and length. The quantities of water were 

 constant, or as nearly so as might be, in the same series of experi- 



