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PROCEEDINGS OF THE AMERICAN ACADEMY 



" Table XXII. — Experiments loith Lead and Graduated Solutions 

 of Sulphate of Magnesia {E-psom Salt). 



" Table XXIII. — Experiments with Lead and Graduated Solu- 

 iions of Chloride of Sodium. 



" Coats that form on Lead. — In seeking to ascertain the nature of 

 the protecting coat which forms in all the waters hitherto experimented 

 with, the influence of organic matter was first considered. 500cc. of 

 each of several waters were evaporated to dryness over a water-bath, 

 ignited, and redissolved in an equal measure of distilled water. There 

 remained a small insoluble residue, which readily dissolved, with effer- 

 vescence, in hydrochloric or acetic acid, — indicating carbonate of 

 lime. Bars of lead were exposed to these prepared solutions. A 

 bluish-white coat formed upon the lead in each. 



