Mr. De la Rue on a Crystallized AUoy of Zinc. 371 



stirring well ; after the oxide had been withdrawn the metal 

 was removed to another vessel to cool ; it weighed about 15 lbs. 

 When partially solidified the fluid portion was drained oflfi 

 leaving a considerable portion of the metal in a spongy state, 

 and occupying the same bulk as the whole mass ; one part of 

 zinc plate residues usually gives the following results : — 



Zinc -673 



Mercury .... •O'iS 



Dross and loss . . 'gS^ 



1-000 

 this average being taken on a quantity of old plates amounting 

 to 2^ hundred weight. 



The spongy residue, examined with the microscope under a 

 power of twenty to fifty times linear, proved to be composed 

 of minute, perfectly clean and well-formed crystals of the form 

 of right rhombic prisms; their breadth varying from the 

 g^^^th to s^o'^h of an inch ; the angles of the base are of about 

 119° and 61 respectively. 



A selected portion, free from scoria, weighing 5 grammes, 

 was subjected to analysis, and found to be an alloy of zinc, 

 iron, lead and copper. After solution in nitric acid the lead 

 was separated as sulphate, which weighed '441 grm. 



The copper being precipitated by sulphuretted hydrogen 

 and then converted into oxide weighed '09 gramme. The 

 iron being thrown down as succinate from the neutralized solu- 

 tion, and after the removal of the soluble salts, washed with 

 ammonia, and ignited, there resulted •184'7 gramme of per- 

 oxide of iron. 



The zinc, precipitated by carbonate of soda, gave when 

 ignited 5*6213 grammes of oxide of zinc. 



These results give the following composition of the alloy : — 



Grammes. Per cent. 



Zinc 4-500 = 90* 



Iron -128 = 2*56 



Lead -300 = 6- 



Copper -072 = 1-44 



5-000 100-00 



These quantities agree very exactly with the following for- 

 mula: — 



Per cent. Per cent. 



Calculated. Found. 



240 Zn = 89-99 90- 



8 Fe = 2-52 2-56 



5 Pb = 6-02 6- 



4 Cu = 1*47 1-44 

 2 B2 



