Am'ju°]y^i889arm*}      Gleanings  from  the  German  Journals.  353 
GLEANINGS  FROM  THE  GERMAN  JOURNALS. 
By  Feank  X.  Moerk,  Ph.  G. 
Salicylic  acid  can  be  examined  for  homologous  acids  (cresotic  acid, 
etc.)  by  taking  advantage  of  the  low  melting  point  of  such  a  mixture. 
Three  gin.  of  the  acid  are  heated  in  a  small  flask  with  15  cc.  water 
and  1—2  gm.  pure  calcium  carbonate  (free  from  iron)  ;  after  efferves- 
cence ceases  the  solution,  without  filtration,  is  evaporated  to  5  cc,  al- 
lowed to  cool,  diluted  with  a  little  water  and  the  solution  poured  off 
from  the  precipitate  into  a  wide  test-tube,  in  which  evaporation  is  con- 
tinued until  1  cc.  remains  ;  by  stirring  with  a  glass  rod  crystallization 
is  hastened  ;  after  diluting  with  1  cc.  water  the  solution  is  passed 
through  absorbent  cotton,  and  after  concentrating  again  to  1  cc.  in  a 
test-tube  the  acids  are  precipitated  by  addition  of  HC1.  If  the  origi- 
nal salicylic  acid  contained  3-5  per  cent,  of  other  acids  the  precipitate 
obtained  above  will  melt  under  hot  water  and  form  a  thick  oily 
liquid  at  the  bottom  of  the  test-tube. — B.  Fischer,  Pharm.  Ztg.,  1889, 
329. 
Estimation  of  sodium  carbonate  in  presence  of  sodium  hydrate. — The 
process  depends  upon  the  combined  use  of  phenol  phthalein  and  Blue 
C.  L.  B.  Poirrier  as  indicators.  The  estimation  is  effected  by  titrating 
in  the  cold  10  cc.  of  a  solution  containing  8-10  gm.  of  the  substance  dis- 
solved in  one  liter,  after  one  drop  of  phenolphthalein  has  been  added 
with  a  standardized  dilute  hydrochloric  acid  (about  3  cc.  acid,  sp.  gr. 
1*16  in  one  liter  water)  until  a  colorless  solution  results;  then  add- 
ing one  drop  of  Blue,  Poirrier,  (1  part  in  400  parts  water)  and  contin- 
uing the  titration  until  the  solution  becomes  dark  blue  (color  of  am- 
moniated  copper  solution).  The  acid  added  after  the  blue  indicator, 
represents  one-half  of  the  carbonate  which  is  present ;  the  total  acid 
added  minus  that  required  by  the  carbonate  will  give  the  acid  required  by 
the  hydrate  present.  It  is  stated  that  the  volume  of  the  finished  titra- 
tion should  not  exceed  50  cc. — Dr.  H.  Goebel,  Chemi Jeer  Ztg.,  1889,  696. 
Mercuric  benzoate  is  made  by  E.  Lieventhal  by  dissolving  125  parts 
mercuric  oxide  in  250  parts  nitric  acid,  sp.  gr.  1*20,  diluting  with 
4000  parts  distilled  water  and  filtering;  188  parts  sodium  benzoate 
are  dissolved  in  4000  parts  distilled  water,  the  solution  filtered  and 
slowly  added,  with  constant  stirring,  to  the  first  solution  ;  the  bulky 
precipitate  is  collected  on  a  linen  strainer,  thoroughly  washed  with 
cold  water,  expressed  and  dried.  The  product  forms  a  light,  white 
powder,  slightly  soluble  in  ether,  alcohol,  chloroform  and  water,  but 
