44 
GLEANINGS  FROM  THE  GERMAN  JOURNALS. 
Quantitative  determination  of  certain  Metals  and  Salts. — In 
the  Jahresbericht  d.  Phys.  Ver.  zu  Frankfurt  a.  M.  (Buchner's 
Kepert.  1859,  294-297,)  Dr.  Julius  Loewe  publishes  researches 
on  the  quantitative  determination  of  silver,  lead,  mercury,  bis- 
muth, and  cadmium  in  the  form  of  sulphides.  The  salts,  particu- 
larly the  nitrates,  of  these  metals,  when  pure  or  mixed  with  sesqui- 
salts  of  iron,  yield  with  sulphuretted  hydrogen  a  precipitate 
which  contains  more  or  less  sulphur,  the  presence  of  which 
hinders  the  calculation  of  the  metals  or  their  oxides  from  these 
precipitates.  The  author,  however,  succeeds  in  removing  the  sul- 
phur by  the  following  manipulation  : — The  precipitate  obtained 
by  a  current  of  sulphuretted  hydrogen  is  collected  upon  a  filter 
which  has  been  previously  well  washed  with  muriatic  acid  and 
water,  then  dried  in  an  air  bath  of  105^0.  (220^  F.),  and  carefully 
weighed.  The  precipitate  is  washed  with  recently  boiled  distill- 
ed water  until  the  washings  cease  to  redden  litmus  paper ;  by 
means  of  a  spritz  it  is  then  washed  into  a  porcelain  dish  and 
slightly  heated  with  a  moderately  strong  solution  of  pure  sul- 
phite of  soda.  A  small  addition  of  hyposulphite  of  soda  ap- 
pears to  be  of  no  disadvantage  ;  on  the  contrary,  the  solution  of 
the  free  sulphur  seems  to  be  accelerated  thereby.  The  sul- 
phide, purified  in  this  manner,  is  collected  again  on  the  same 
filter,  well  washed  and  dried  at  105°  C.  in  the  air-bath.  The 
weight  of  the  metal  or  the  oxide  is  then  calculated  in  the  usual 
manner. 
The  same  journals  also  contain  a  paper  by  the  same  author  on 
the  quantitative  separation  of  sulphate  of  lead  from  sulphate  of 
baryta,  the  former  of  which  is  dissolved  by  a  filtered  concen- 
trated solution  of  hyposulphite  of  soda;  heated  not  over  20°  C, 
(68°  F.)  in  order  to  prevent  the  precipitation  of  sulphide  of 
lead.  The  sulphate  of  baryta  remains  behind ;  the  sulphate  of 
lead  may  be  calculated  by  precipitating  the  solution  either  with 
sulphuretted  hydrogen,  with  an  acid,  or  with  the  neutral  chro- 
mate  of  patassa ;  sulphide,  sulphate  and  chromate  of  lead  re- 
spectively are  thus  obtained. 
To  separate  oxide  of  copper  from  oxide  of  iron  for  analytical 
purposes,  by  means  of  ammonia,  Dr.  Julius  Loewe  (see  the 
above  named  journals)  proceeds  as  follows :— -The  solution  of  their 
