DR. J. P. JOULE ON SOME AMALGAMS. 



123 



No. 



Mercury. 



Zinc. 



Sp. grav. 



Eemarks. 



I. 



2. 



3- 



lOO 



55 



39-4 



122*8 

 184-9 



ii'34 

 8-935 

 8-349 



White and crystalline. 



Ditto ditto. 

 Prepared from hot sulphate of zinc. 



The first of the above three specimens^ consisting of an 

 equivalent of each metal^ appears to be the amalgam 

 which^ containing the largest quantity of mercury _, is yet 

 solid. The specific gravity indicates a certain contraction 

 of volume, but not nearly as much as that in the amalgams 

 of silver and copper, but such as would place the specific 

 gravity of the mercury at 14' i. Pressure seemed to have 

 the efiect of decomposing this amalgam, or at least of 

 expeUiDg mercury, until the amalgam consisted of about 

 one equivalent of mercury to three of zinc. 



No. 



Pressure. 



Mercvn-y. 



Zinc. 



I. 



2. 



3- 

 4- 

 5- 



^ ton for I day 



i^ ton for I day 



50 tons for I hour 



ditto 



ditto 



100 



)) 

 ?) 

 )) 



)5 



59-25 

 69 

 76-7 

 79-6 



75'9 



Amalgam of Lead. — On making mercury negative in 

 acetate of lead, a crystalline amalgam was gradually formed. 

 The operation was stopped when the characteristic flat 

 blue crystals of lead began to make their appearance. 

 The amalgam was found to have a specific gravity of 12*64 

 (indicating 13-85 for its mercury), and to consist of 100 

 mercury to 69*83 lead, and, allowing for unavoidable ex- 

 cess of mercury, may be considered as a binary compound. 



To ascertain the effect of pressure, a liquid amalgam 

 was formed by heating the two metals together. It was 

 then compressed with a force of three tons to the square 

 inch for a day. A greater pressure than this would have 

 caused the amalgam as well as the mercury to escape from 

 the press. -The result was a mass of bright crystals, easily 

 fractured, which had a specific gravity of I2*ii, and was 



