120 



DR. J. P. JOULE ON SOME AMALGAMS. 





Pressure per 











No. 



square inch, 

 in tons. 



Time. 



Mercury. 



Copper. 



Sp. grav. 



I. 



3 



12 hours 



100 



20'3 





2. 



1 



12 hours 



55 



17-28 





3. 



I 



36 hours 



55 



20-5 





4- 



li 



17 hours 



55 



18-95 





5- 



2 

 r gradually 



12 hours 



J> 



18-4 





6. 



increased ■ 

 [ up to I ton 



3f months 



55 



39-02 



1276 





r 



1 3 days, with 









7- 



55 



intervals 

 amounting to 



55 



38-43 



12*56 







54 days 







8. 



9 



a few minutes 





25-84 



12-92 



9- 



15 



j> 





28-57 





10. 



18 



jj 





28-4 



13-01 



II. 



20 



j» 





29-46 





12. 



72 



jj 





30-95 



13-06 



13- 



72 



5) 





32*82 



12-93 



14. 



144 



>J 





35-13 



12-96 



15- 



144 



5> 





34-87 



12-57 



16. 



144 



55 





35-63 



12-62 



17- 



20 



30 minutes 





33*04 





18. 



36 



30 minutes 





30-25 



12-88 



19. 



72 



I hour 





32-34 





20. 



30 



2 hours 





40-18 





21. 



30 



7 hours 





44-34 



12-38 



On inspecting the above Table^ it will appear tliat a 

 moderate pressure continued for a short time leaves a 

 binary compound of the metals along with the quantity of 

 mercury which may be supposed to be entangled among 

 the crystals. When the pressure was very great_, or was 

 continued for a long time^ the resulting amalgam inva- 

 riably contained more than one equivalent of copper. I 

 believe that this arises from a decomposition of the binary 

 amalgam by the violent mechanical means adopted. 



On the supposition that the copper retains its own 

 specific gravity, the density of the above amalgams gives 

 for the mercury a specific gravity of 14*985. 



The Amalgam of Silver was generally produced by treat- 

 ing mercury with nitrate of silver. The action goes on 

 until a hard mass of shining crystals is formed,, consisting 

 of about an equivalent of silver to one of mercury. 



