370 Mr. De la Rue oji a Crystallized Alloy of Zinc. 



Delafield, Long Acre. An imperial gallon of the water con- 

 tained 56*45 grains of solid matter, 100 parts of which gave- — 



Carbonate of soda 20*70 



' Sulphate of soda 42"94 



Chloride of sodium 22*58 



Carbonate of lime 10*96 



Carbonate of magnesia .... 1*92 



Phosphate of lime 0*34 



Phosphate of iron 0*43 



Silica 0*79 



100*66 

 The growth of green confervse in this water is extremely 

 rapid, and occasions inconvenience when the water is kept in 

 open tanks. It is a subject perhaps worthy of inquiry, whe- 

 ther the value of some waters for irrigation may not depend 

 upon their containing phosphoric acid, this constituent having 

 hitherto been generally overlooked in waters. 



LVII. On a Crystallized Alloy ofZinc^ Iron^ Lead and 

 Copper. By Warren De la Rue, Esq.*^ 



THE alloy in question was obtained from the worn-out 

 amalgamated zinc plates used in the voltaic battery after 

 the mercury had been recovered by distillation. As the sul- 

 phate of zinc, resulting from the solution of the zinc in the 

 battery, is exceedingly pure, it follows that the residue of the 

 plates contains, besides the mercury used for amalgamation, 

 most of the impurities contained originally in the whole plates, 

 and the metal obtained therefrom is consequently much infe- 

 rior in quality to the original rolled zinc. 



Zinc in a fit state for rolling is obtained by running off the 

 fluid portion from a mass of cast zinc which has been allowed 

 to cool down to a certain point after fusion, the metal left be- 

 hind being less pure than that which flows off*. The manu- 

 facturer who furnishes me with rolled zinc and takes back the 

 zinc obtained from the worn-out plates, informed me that the 

 latter is unprofitable to re-work from its leaving an unusually 

 large residue in refining ; this statement induced me to inves- 

 tigate the composition of this residue, and 1 proceeded in the 

 following manner. 



About 22 pounds of worn-out plates being introduced into an 

 iron pot, and the mercury distilled oft' by heating it to redness, 

 the fused metal was fined by adding a quantity of tallow and 



* Communicated by the Chemical Society j having been read May 5, 

 1845. 



