APPARATUS  FOR  TAKING  SPECIFIC  GRAVITY.  173 
platinum,  but  weakly  to  glass  or  porcelain,  from  which  surfaces 
it  is  easily  removed  by  the  finger.  It  is  readily  sublimed,  pro- 
ducing the  garlic-like  odor.  There  is  no  ambiguity  in  the  re- 
sults ;  if  antimony  be  present  it  remains  fixed  on  the  platinum. 
The  apparatus  I  have  employed  is  simple,  a  twelve  ounce  phial, 
with  a  mouth  about  an  inch  in  diameter,  having  a  tight  cork, 
furnished  with  a  funnel  tube  reaching  nearly  to  its  bottom,  and 
a  small  tube  drawn  out  to  a  point  for  the  discharge  of  the  gas. 
The  zinc  I  employed  was  in  the  state  of  small  lumps  or  in  grains, 
and  the  sulphuric  or  muriatic  acid  very  diluted,  viz.,  one  volume 
of  acid  to  from  15  to  20,  and  even  25  volumes  of  water  Chem. 
ist,  Oct.  1856. 
APPARATUS  FOR  TAKING  SPECIFIC  GRAVITY. 
By  Messrs.  Eckfeldt  and  Dubois. 
From  Proceedings  of  American  Philosophical  Society. 
The  apparatus  for  taking  specific  gravity  of  solids,  is  essen- 
tially a  tin  cup  with  a  spout  at  the  side.    Five  vessels  are  here 
shown,  of  different  sizes  and  shapes,  to  suit  different  cases.  Four 
of  these  are  cylindrical,  raging  from  six  to  ten  inches  high,  and 
from  two  to  five  inches  in  diameter.    The  tall  one  (ten  inches 
by  two),  is  intended  for  the  trial  of  silver  spoons  and  forks,  or 
articles  of  similar  shape  ;  the  others  are  adapted  to  lumps  of 
stone  or  metal,  or  blocks  of  wood,  of  various  sizes.    The  fifth 
vessel  is  rectangular,  measuring  6  J  inches  high,  1  j  inches  long, 
and  J  inch  broad,  being  intended  for  coins,  not  smaller  than  the 
half  eagle  or  quarter  dollar,  and  for  small  medals  and  gems  of 
admissible  size.    This  vessel  is  provided  with  a  brass  plate,  as  a 
plunger,  for  diminishing  the  surface.    The  smaller  vessels  are 
set  firmly  in  mahogany  blocks,  to  insure  steadiness  in  the  opera- 
tion ;  and  these  blocks  have  screw  feet,  for  convenience  of  level- 
ling.   The  spouts  extend  upward,  with  a  curve  outward,  the  beak 
being  far  enough  below  the  top  of  the  cup  to  allow  for  the  space 
to  be  taken  up  by  the  specimen,  that  it  may  not  force  the  water 
over  the  top  nor  leave  any  point  uncovered  by  water.    The  aper- 
ture of  the  spout  is  tapered  to  the  one-sixteenth  of  an  inch,  and 
a  small  bit  of  wire  projects  downwards  from  the  beak,  to  carry 
the  drops  of  water  properly.    A  small  cup  is  placed  directly 
under,  to  catch  the  water  displaced,  and  a  brass  weight,  equal 
