136 Scientific Intelligence. 
kets) placed on inclined tables. The skins are washed out in vats 
every hour and the blankets at longer intervals. No merewyis 
used in the batteries under the stamps, amalgamation being restric 
ted to the cua aa from the skins, &c., which are subse, 
we 
Years he | 1850. a 1852, ee 1854, 11855. a 
psi 
otis raised. tons. 67,336 67, 10079, 810189, 628s ,608|86,048)87,207)80 
Binet ore stam mped, to ons, 69,004 64.3 
Gold produced, Ibs. oe 2,583 att 
Years. ps8 | 1850. | 1800. | 1861. |e [358 1963, | 1864. 164 |i 
Stone & orestamp'd, ‘tone, 87/270 0 880 | 74,528 | 71,902 | 67, 508 ran rated sae 
Gold produced, Ibs. Troy,| 2733 3.294| 3°974| 5,051 Se ae |" 91852 48 
Net profit, Sag. [R55 ROG G.0| 700 | || IM 
* Loss, £14,629, 
‘This amount of work was done by 135 stamps striking an averig 
of 55°84 blows per mifiute (the stamp when new weighing "45 
the lifters, &e., 640 Ibs.), for 356°27 days per year, crushing 1 
tons of stuff per day, or 2,683 Ibs, per day per head. 
The total value of the — metals extracted 
3057] 31326) 8625) 3,464) 3,325] 2 ¥ 
"sr 86,433|96,848 aati 
Stone raised, tons, 88,901 | 88,968 | 91,361 | 96,612 / 90,806 | 84 
to close of 1865 has been.....:.-..-------- £2,902, 480 ial 
The total quantit 24 mineral eniadbissce Scie 769,050 
The average yield of ore ..2........---------- 333 oitats 
a manly as eponeble, half au ounce Troy, “yale 
328.6d.* ‘The ores have on the whole been poor, ee the yield t 
i at 
ce, : 
Of 1000 parts of ore stamped at Morro Velho, the relative 
portions of slimes and fine sand are found to be thus 
Passing a sieve of 10,000 holes per ae: inch, gs to 9 ne 
Tora passing a = of 2 ,500 holes 0-28 « 0°50 
stamping is t us seen to be extremel ao 
The auriferous material j pening. are m the stamping mills ss 
ciated with gold in three differen ; | 
* An oitava is 2 dwt. 7-348 grains a or 867425 oitavas <= 1 0% Tor 
