CRYSTALLIZED  GUAIACUM  RESIN. 
247 
Its  composition  when  thoroughly  dry  represents : 
Oxide  of  bismuth  53 
Tannin  47 
100 
The  above  mode  of  preparation  is  very  simple  and  at  the  same 
time  the  most  rational.  Most  of  the  insoluble  tannates  are 
obtained  by  double  decomposition  ;  but  the  salts  of  bismuth  and 
especially  the  nitrate,  are  in  great  part  decomposed  by  water, 
and  to  keep  them  in  solution  it  is  necessary  to  have  a  great 
excess  of  acid,  which,  in  the  present  case,  would  prevent  the 
precipitation  of  the  tannate  of  bismuth.  It  is  better  then  to 
effect  the  combination  directly,  by  acting  on  one  equivalent  of 
oxide  of  bismuth  with  one  equivalent  of  tannic  acid.  The  tannic 
acid  may  be  dissolved  in  alcohol,  ether,  or  even  water,  and  then 
the  tannin  obtained  in  a  resiniform  mass  can  be  used,  which  is 
cheaper  than  that  obtained  in  the  usual  form. 
The  tannate  is  administered  in  doses  of  30  grains. — Rep.  de 
PL  and  Ohem.  News,  Feb.  25,  1860. 
CRYSTALLIZED  GUAIACUM  RESIN. 
Prof.  Hlasiwetz  has,  after  a  long  trial,  found  a  way  to  change 
the  greater  part  of  guaiacum  resin  into  crystals.  He  dissolves 
a  pound  of  the  resin  in  as  much  alcohol  as  will  make  a  solution 
of  the  consistence  of  a  thin  syrup.  This  he  strains  through  fine 
linen,  and  adds  gradually,  while  still  warm,  half  a  pound  of 
caustic  potash  in  spirit,  shaking  them  together.  The  whole  is 
allowed  to  stand  in  a  bottle  about  24  hours.  The  magma  ob- 
tained is  then  transferred  to  a  strong  linen  cloth,  and  the  fluid 
part  carefully  pressed  out.  The  moist  cake  is  washed  with 
strong  alcohol  until  the  alcohol  runs  away  but  slightly  colored. 
The  mass  is  again  pressed,  then  triturated  with  a  small  quantity 
of  water,  and  afterwards  heated  in  a  dish  until  reduced  to  a 
uniform  consistence.  It  is  then  transferred  to  a  filter  and 
washed  with  cold  water  until  the  salt  is  white,  and  the  water 
runs  away  colorless.  This  potash  salt  (which  is  but  slightly 
soluble  in  alcohol  and  water)  may  be  obtained  crystalline  by 
dissolving  it  in  a  large  quantity  of  dilute  alcohol  at  the  boiling 
