Am.  Jour.  Pharm.  \ 
July,  1886.  j" 
Investigation  of  Tannins. 
349 
After  these  fruitless  attempts  to  obtain  lithium  bicarbonate  in  a 
dry  condition,  it  is  surprising  that,  nevertheless,  a  "lithium  bicar- 
bonicuni"  figures  in  commerce.  I  have  purchased  a  sample  of  this 
commercial  lithium  bicarbonicum  from  one  of  our  best  houses  and 
examined  it.  It  proved  to  be  not  a  bicarbonate,  but  a  crystallized 
monocarbonate,  corresponding  exactly  with  that  which  I  obtained 
by  evaporating  a  solution  of  lithium  bicarbonate  in  a  water-bath. 
There  no  more  exists  a  lithium  bicarbonate  or  sesquicarbonate  in  the 
dry  condition  than  magnesium  or  calcium  bicarbonate. 
It  is  probably  not  superfluous  to  remark  that,  in  my  experiments,  I 
observed  that  lithium  carbonate,  upon  being  heated  to  redness  in  a 
glass  tube  or  porcelain  dish,  very  readily  attacked  the  glass  or  porce- 
lain, carbonic  acid  being  given  off.  I  have  determined  a  loss  of  as 
much  as  6  per  cent.,  while  so  much  silicic  acid  entered  into  com- 
bination with  the  lithium  that,  after  dissolving  the  residue  in  dilute 
hydrochloric  acid,  the  liquid  became  gelatinous.  According  to 
Fhickiger,  lithium  carbonate  also  gives  off  carbonic  acid  on  prolonged 
boiling  with  water. — Phar.  Jour,  and  Trans.,  May  15,  p.  964. — Phar, 
Centralhatte,  April  1. 
INVESTIGATION  OF  TANNINS. 
By  F.  Notzli. 
After  some  introductory  remarks  on  the  preparation  and  chemical 
constitution  of  the  tannic  acid  of  oak-bark,  the  author  gives  an  outline 
of  the  different  methods  proposed  for  estimating  the  tannin  in  barks 
and  other  tannin  materials.  .  He  then  discusses  at  some  length  the 
methods  recommended  by  Lowenthal,  Simand,  and  Procter,  and  as 
an  outcome  of  his  researches,  describes  a  modified  method  for  esti- 
mating tannins.  The  process  involves  the  use  of  (1)  a  permanganate 
solution  containing  1  gm.  of  potassium  permanganate  per  litre, 
standardized  with  iron  or  oxalic  acid ;  (2)  a  solution  of  indigo  pre- 
pared by  dissolving  125  gms.  of  indigo-carmine  paste  in  6  litres  of 
water,  adding  400  c.c.  of  concentrated  sulphuric  acid,  and  filtering 
the  mixture;  (3)  a  gelatin  solution,  20  gms.  per  litre,  to  be  prepared 
every  day,  as  it  decomposes  very  rapidly;  (4)  dilute  sulphuric  acid, 
1  kilo,  per  10  kilos,  of  water ;  (5)  pure  sodium  chloride ;  and  (6) 
kaolin.  To  effect  the  titration,  10  c.c.  of  extract  of  bark  (or  5  c.c.  in 
case  of  rich  barks)  is  transferred  to  a  large  porcelain  basin  and  treated 
