^""'ATr'^mo''^'}  Gleanings  from  the  German  Journals.  133 
Karlsbad- Sprudel  Salt  (see  also  "  Amer.  Jour.  Phar.,"  1878,  p. 
474,  and  1879,  p.  454).    Dr.  Harnack  states  that 
The  genuine  anhydrous  salt  contains  sodium  sulphate,  99*33  per  cent  ; 
sodium  carbonate,  0*45  per  cent.,  and  sodium  chloride,  0*076  per  cent., 
and,  therefore,  is  nearly  pure  Glauber's  salt,  from  which  it  differs 
chiefly  in  being  30  times  more  expensive. 
The  artificial  salt  contains  much  more  soda,  is  made  usually  by  allow- 
ing a  solution  of  200  parts  of  crystallized  sodium  sulphate,  30  parts  of 
crystallized  sodium  carbonate  and  5  parts  of  sodium  chloride  to  crystal- 
lize, is  not  uniform,  and,  therefore,  objectionable,  for  which  reason  the 
author  suggests  the  adoption  of  an  officinal  formula  directing  a  mix- 
ture of  the  powdered  salts. — Pharm,  Ztg.^  Jan.  21,  1880,  p.  38,  from 
Klin.  Wochenschr. 
Ferric  Hydrates.— The  trihydrate,  Fe2(OH)Q,  has  never  been  pre- 
;pared  thus  far  according  to  Tommasi,  who  mentions  the  existence  of 
two  isomeric,  respectively  red  and  yellow,  monohydrates,  Fe202(OH)2, 
and  bihydrates,  Y^^(OY{\^  and  publishes  the  following  distinctions  : 
The  red  bihydrate  remains  unaltered  up  to  50°C.  and  the  yellow  to 
I05°C.;  the  red  monohydrate  to  92°  and  the  yellow  to  I50°C.  The 
red  hydrates,  when  dehydrated,  leave  as  a  residue  a  brown  oxide  hav- 
ing the  density  5*1,  while  the  yellow  hydrates  leave  a  red  or  reddish- 
yellow  oxide  having  the  density  3*95.  The  red  hydrates  dissolve  even 
in  dilute  acids,  while  the  yellow  are  scarcely  soluble  in  concentrated 
acids.  The  red  hydrates  are  readily  dissolved  by  ferric  chloride  solu- 
tion, and  this  solution  yields,  on  the  addition  of  sodium  sulphate  or  sul- 
.phuric  acid,  a  precipitate  of  hydrated  oxide  ;  the  yellow  hydrates  are 
insoluble  in  ferric  chloride.  The  red  hydrates  are  entirely  dehydrated 
by  boiling,  while  the  yellow  are  only  reduced  to  monohydrates.  Tom- 
masi considers  the  combinations  of  ferric  hydrates  with  ferric  salts 
mere  mechanical  mixtures  and  not  chemical  compounds. — Ber,  d. 
Deutsch,  Chem.  Ges.^  1879,  p.  1929. 
Determination  of  Metallic  Iron  in  Reduced  Iron. — G.  Vulpius 
proposes  the  following  process  :  Digest  i  gram  of  the  iron  for  one 
hour  with  a  solution  of  5  grams  of  pure  copper  sulphate  in  25  grams 
of  water,  acidulated  with  2  drops  of  dilute  sulphuric  acid,  filter  into  a 
previously  weighed  flask,  wash  the  filter  with  sufficient  distilled  water 
to  obtain  50  grams  of  filtrate,  add  i  gram  of  pure  powdered  iron  (the 
percentage  of  carbon  contained  in  it  should  be  previously  determined), 
digest  until  all  the  copper  is  precipitated  in  a  metallic  state,  add  5  grams 
