402 
IMPURITIES  OF  COMMERCIAL  ZINC. 
There  is  no  doubt  but  this  milk  contained  one  half  its  mea- 
sure of  water  ;  but  from  the  small  amount  of  butter,  it  may  be 
possible  that  it  was  manufactured  from  fresh  milk  and  skimmed 
milk  each  one  part,  and  water  two  parts. 
I  have  examined  it  for  chalk  and  magnesia,  but  found  it  free 
from  both. 
Philadelphia,  August,  i860. 
ON  THE  IMPURITIES  OF  COMMERCIAL  ZINC, 
With  special  reference  to  the  residue  insoluble  in  diluted  acids,  to  sulphur, 
and  to  arsenic. 
By  Charles  W.  Eliot  and  Frank  H.  Storer. 
The  above  is  the  title  of  a  valuable  paper  read  before  the 
American  Aeademy  of  Arts  and  Sciences,  May  29th,  1860, 
and  published  in  vol.  viii.  new  series,  of  its  memoirs,  of  which 
it  occupies  forty  pages  quarto.  The  importance  of  pure  zinc 
in  chemical,  and  especially  in  medico-legal  researches,  has  been 
a  prompting  motive  with  the  authors  in  their  work. 
In  order  to  make  the  results  as  general  as  possible,  the 
authors  obtained  authentic  specimens  of  zinc  from  the  following 
sources,  viz : 
1.  Silesian  zinc. 
2.  Vieille  Montagne  (Belgium)  zinc. 
3.  New  Jersey  (American)  zinc. 
4.  Pennsylvania  zinc,  (Pennsylvania  and  Lehigh  zinc  works, 
Bethlehem,  Pa.) 
5.  Vieille  Montagne  zinc,  such  as  is  used  in  the  U.  S. 
Mint. 
6.  A  zinc  labelled  "  Zinc  pur,"  Rousseau  Freres,  Paris. 
7.  A  sheet  zinc  of  unknown  origin  obtained  at  Berlin 
(Prussia.) 
8.  An  English  zinc,  made  near  Wrexham,  North  Wales. 
9.  An  English  zinc  from  the  Mines  Royal,  Neath,  Glamor- 
ganshire. 
10.  An  English  zinc  from  the  works  of  Dillwyn  &  Co., 
Swansea. 
11.  An  English  zinc  from  the  works  of  Messrs.  Vivian, 
Swansea. 
