810 Intelligence and Miscellaneous Articles. 



longer periods. This unnoticed result was communicated to me by 

 Sir J. Herschel in a letter as long back as 1845." 



With regard to the second group, the period of revolution of the 

 seventh satellite, Hyperion, is live times that of the fifth, Rhea : and 

 the period of the eighth, Japhet, five times that of the sixth. Titan. 



These results will be best shown by the following table containing 

 the elements of comparison : — 



Satellites. Periods of revolution. 



1. Mimus 0-943 . 



2. Enceladus 1-370 . 



3. Tethys 1-888 . 



4. Dione 2-789 . 



5. Rhea 4517 . 



6. Titan 15*945 . 



7. Hyperion 22500?. 



8. Japhet 79330 . 



Of the satellites of Jupiter, it is known that the period of revo- 

 lution of the first is about one-half that of the second, which is itself 

 again one-half the period of the third satellite. M. Behr also points 

 out that the period of revolution of the fourth satellite is double that 

 of the third, plus J of the difference between the periods of the 

 second and the first. 



Satellites. Periods of revolution. Reduced numbers. 



1 a = i-769 ... 2a = 3-538 



2 b = 3-551 b — 3-551 



3 c = .7-155 ..., Jc= 3 577 



4 rf = 16-699 ....2c-f |(6-a) =16-686 



Proc. Acad. Roy. de Belgique, 



ON THE DISTRIBUTION OF GOLD. 

 My dear Francis, 



As considerable interest is felt at the present time concerning the 

 diflfusion of gold over the earth's surface, it may be interesting to 

 the readers of the Philosophical Magazine to be informed of the 

 results of an investigation of that subject, which is now being carried 

 on at the Government School of Mines. So far as that investiga- 

 tion has extended, I may state that a sensible and visible amount of 

 gold has been extracted from every variety of British and foreign 

 lead, as well as every specimen of litharge, minium, white lead, and 

 acetate of lead, which have been examined. It has also been 

 extracted in very sensible proi)ortion from commercial bismuth. 

 Between thirty and forty determinations have already been made. 



