Am Nov.^i89oarm* }  Gleanings  from  the  German  Journals.  583 
iron  impurity  is  introduced  by  keeping  the  acid  in  iron  containers 
(an  acid  of  66°  B.  will  not  dissolve  iron,  but  one  of  the  strength  of 
6o°  B.,  will  dissolve  small  quantities).  The  best  means  of  prevent- 
ing the  red  color  is  to  denitrate  the  acid  by  addition  of  a  little 
ammonium  sulphate  ;  the  color  may  also  be  discharged  by  heat. — 
R.  Nbrrenberg  (Chem.  Industrie),  Pharm.  Ztg.,  1890,  595. 
Recovery  of  silver  and  gold  from  potassium  cyanide  solutions. — 
To  recover  silver  it  is  only  necessary  to  suspend  a  piece  each  of 
sheet  zinc  and  sheet  iron  in  the  solution  for  two  days,  collect  the  fine 
deposit  of  silver  which,  however,  generally  contains  some  copper, 
wash,  dry,  dissolve  in  concentrated  sulphuric  acid,  dilute  with  water 
and  precipitate  the  dissolved  silver  by  suspending  a  strip  of  copper 
in  the  solution. 
To  recover  gold  add  to  every  100  litres  of  solution  one-half  kilo- 
gram zinc  dust,  agitate  frequently  during  two  or  three  days,  collect 
the  precipitate  containing  gold  and  quite  often  silver  and  copper, 
wash,  and,  by  treatment  with  hydrochloric  acid,  remove  the  excess 
of  zinc  and  then  by  use  of  nitric  acid  the  silver  and  copper  ;  the 
residue  remaining  will  be  pure  gold. — Stockmeier  and  Fleischmann 
(Industrie  Blatter)  Chem.  tech.  Central.  Anzeiger,  1890,  373. 
A  new  albumin  test. — To  8- 10  cc.  of  the  suspected  urine  add  an 
equal  volume  of  strong  hydrochloric  acid  and  then,  without  agita- 
tion, with  a  pipette  2-3  drops  of  a  concentrated  solution  of  chlori- 
nated lime  ;  the  presence  of  per  cent,  albumin  will  cause  a  white 
turbidity  in  the  upper  part  of  the  test.  By  diluting  albumenoid 
urine  with  known  quantities  of  water  until  the  test  in  the  diluted 
urine  is  no  longer  obtained  a  rapid  and  approximate  estimation  of 
albumin  may  be  made. — Dr.  A.  Jolles  (Presenilis  Ztschr.  f.  an.  Chem) 
Pharm.  Post,  1890,  781. 
The  preparation  of  pure  gases,  carbon  dioxide,  sulphur  dioxide, 
etc.,  is  conveniently  carried  out  by  mixing  acid  sulphate  of  sodium 
with  the  acid  or  neutral  salt  which  contains  the  gas  desired.  To 
make  C02,  for  instance,  the  acid  carbonate  and  acid  sulphate  of 
sodium  are  taken  in  molecular  proportion,  placed  in  a  generating 
flask  and  a  little  water  added  ;  a  steady  and  prolonged  evolution  of 
pure  but  moist  gas  results. — H.  Borntrager  [Ztschr.  f.  an.  Chem.)  Rpt. 
der  Pharm.,  1890,  213. 
Linoleic  acid. — The  formula  of  this  acid  has  been  ascertained  to 
