/ 
174  APPARATUS  FOR  TAKING  SPECIFIC  GRAVITY. 
to  the  weight  of  this  cup  when  empty,  is  found  convenient 
ough  not  necessary)  as  a  counter-weight. 
When  the  operation  is  to  be  performed,  suppose  upon  a  gold 
or  silver  ore,  the  ore  is  first  weighed,  and  afterwards  its  surface 
is  moistened.  The  vessel  is  then  nearly  filled  with  water,  and 
so  much  as  is  superfluous,  or  above  the  level  of  the  beak  of  the 
spout,  runs  or  drips  off,  to  a  final  drop.  The  small  cup  is  then 
set  under  the  beak,  and  the  lump  is  carefully  lowered  into  the 
vessel  by  a  hair  wire  or  waxed  thread.  This,  of  course,  displaces 
its  own  bulk  of  water,  which  runs  off  into  the  small  cup,  gradu- 
ally coming  back  to  the  former  level,  by  a  final  drop.  The 
weight  of  this  water  is  the  divisor,  the  weight  of  the  lump  the 
dividend,  and  the  quotient  is  the  specific  gravity. 
In  connection  with  this  apparatus,  the  following  miscellaneous 
remarks  are  offered  to  the  Society. 
The  opening  of  the  gold  mines  of  California  brought  out  a 
great  number  of  beautiful  specimens  of  gold  in  the  matrix  (or 
mingled  with  quartz)  of  the  most  fanciful  forms,  and  every  variety 
of  size  and  value.  In  many  cases  it  was  presumed,  by  the  holders 
of  these  prizes,  that  they  would  bring  more  money,  as  curiosities, 
than  as  bullion  ;  and  at  any  rate,  very  many  owners  were  un- 
willing to  have  such  attractive  specimens  spoiled  until  they  had 
been  sufficiently  exhibited.  At  the  same  time,  it  was  always 
desirable  to  know,  pretty  nearly,  how  much  gold  was  actually 
contained ;  and,  to  obtain  such  estimates,  upon  what  was  sup- 
posed to  be  reliable  authority,  many  of  these  specimens  were 
brought  to  the  assay  office  of  the  mint.  They  came  at  a  time 
when  we  were  overpowered  with  the  legitimate  business  of  the 
office,  and  yet  it  seemed  impossible  to  refuse  such  requests ;  and, 
for  a  considerable  time,  such  employment  was  interesting  as  a 
matter  of  scientific  inquiry.  Especially  when  we  could  compare 
our  estimates  with  the  more  definite  and  accurate  results  obtained 
by  putting  specimens  or  "nuggets"  through  the  regular  routine 
of  melting  and  assay.  On  one  occasion  a  lump,  weighing  over 
200  gounds,  came  to  us  for  this  purpose.  It  was  sent  by  the 
Isthmus  route,  at  a  time  when  transportation  was  enormously 
dear,  and  having  visible  gold  on  the  surface,  was  expected  to  be 
rich  throughout  the  mass  ;  and,  with  this  expectation,  was  on  the 
way  to  London,  to  make  an  impression  upon  the  stock  market 
