70  Gleanings  from  the  German  Journals.  {Am'^eb.r"i5Sfiarm' 
schonn  to  prepare  sodium  acetate  from  perfectly  neutral  and  also 
from  distinctly  acid  solutions;  the  action  towards  litmus  paper  and 
even  towards  phenolphthalein  proved  that  the  solution  of  the  salt  is 
alkaline  to  both  indicators  and  that  the  salt  could  contain  small 
quantities  of  free  acetic  acid  without  changing  the  result.  In  the 
titration  of  acetic  acid  with  sodium  hydrate  solution  neither  of 
these  indicators  will  give  exact  results.  Fifty  grams  sodium  acetate 
(containing  no  free  acetic  acid)  dissolved  in  50  grams  water  required 
in  cold  solution  1  cc.  hydrochloric  acid  to  give  neutral  reaction 
towards  phenolphthalein  ;  if  the  solution  be  boiled,  3  cc.  more  of 
the  acid  must  be  added  to  give  neutral  reaction.  The  addition  of 
4  cc.  acid  to  this  solution  still  gave  a  liquid  having  alkaline  reaction 
tested  with  litmus  or  turmeric  paper.  To  test  the  acetate  for  car- 
bonate it  is  recommended  to  dissolve  10  gm.  of  the  salt  in  100  gm. 
of  water,  and  add  t-2  drops  phenolphthalein  solution  ;  in  the 
absence  of  carbonate  of  sodium  one  drop  ^-hydrochloric  acid  will 
decolorize  the  solution. —  Chcmiker  Ztg.,  1892,  1921. 
Cholera.culture  reaction. — If  to  a  cholera-culture  in  gelatin  or 
beef-tea  a  small  quantity  of  concentrated  sulphuric  acid  be  added  a 
red  coloration  appears,  frequently  called  the  cholera-red  reaction. 
A  study  of  the  conditions  of  the  reaction  shows  it  to  be  due  to  the 
action  of  indol  upon  nitrous  acid  produced  by  the  reducing  action 
of  the  comma-bacillus  from  nitrates  present  in  the  nourishing  me- 
dium. A  series  of  experiments  prove  that  this  cholera  test  is  superior 
to  other  known  tests  for  nitrous  acid  (diphenylamine,  sulphanilic 
acid  and  naphthylamine,  and  potassium  iodide,  starch  and  hydro- 
chloric acid).  The  red  color  with  the  cholera-culture  is  interfered 
with  by  an  excess  of  pepton,  the  presence  of  2  per  cent,  pepton 
completely  preventing  the  coloration,  but  upon  the  addition  of  a 
little  nitrite  it  becomes  apparent.  The  larger  the  quantity  the  indol 
present  the  deeper  red  the  color,  small  quantities  of  nitrite  answer- 
ing as  well  as  larger  quantities.  As  a  test  for  nitrons  acid  in  the 
presence  of  considerable  organic  matter,  indol  in  the  presence  of 
sulphuric  acid  forms  the  most  delicate  test. — M.  W.  Beyerinck 
{Centralbl.  f  Bakt.,  etc.,)  Apotheker  Ztg.,  1892,  666. 
Action  of  hydrogen  sulphide  upon  the  organism. — By  an  elaborate 
investigation  is  established  that  the  inhalation  of  0  07  per  cent, 
to  O  08  per  cent.  H2S  in  the  atmosphere  produces  in  man,  in  the 
