ALKALIMETRIC TEST. 49 



Action of Salt-ivater upon Copper. — Dr. Percy has deter- 

 mined by experiment (Athengeum 1849, Ch. Gaz. vii.), that 

 the presence of phosphorus and iron in copper, even in the 

 proportion of 2.41 of each in the 100 parts, scarcely impairs 

 either its tenacity or malleability. Copper, alloyed with a 

 little phosphorus, was also found to resist the action of salt- 

 water much better than other specimens of copper. 



Grains. 



Electrotype copper, after 9 months' immersion in sea- 

 water, lost per sq. inch 1.4 

 1.1 

 0.0 

 1.12 

 1.6G 

 3.0 

 2.48 

 2.33 

 0.95 



3. Lead. — Nearly all the lead of commerce is obtained from 

 galena, or sulphuret of lead. One of the most extensive 

 formations of oxidized lead (carbonate) is in Mine a la Motte, 

 Missouri, where millions of pounds of metal have been ex- 

 tracted from white-lead. 



The total amount of lead-ore raised in Great Britain, in 

 1849, was 78,904 tons, which yielded 54,853 tons of metal ; 

 of this amount, England produced about three-fourths. The 

 average yield of the ores of Great Britain is 69J per cent. 



Shot. — David Smith, of New York, has patented a plan for 

 making shot in a comparatively low tower, by forcing or 

 drawing an upward current of air through it, so that the 

 descending shot will be brought in contact with as much cool- 

 ing air in 50 feet as it ordinarily docs in descending 150 feet 

 or more. 



Alkalimetrie Test. — Domont^ has described (Technologiste, 



1846) a method of testing lead quantitatively, similar to that 



of Pelouze for copper (see above). The substance to be tested 



is dissolved in nitric acid, the solution, diluted with water, 



£ 4 



