^ul™?,wt"'\      Pyrogallic  Acid  as  a  Reagent.  283 
sition  of  this  hydrocarbon.  It  has  a  turpentine-like  odor,  is  trans- 
parent, soluble  in  alcohol  and  ether,  and  at  0°  has  a  specific  gravity 
0-8793.  It  combines  with  hydrochloric  acid,  forming  a  crystalline 
mass  which  melts  at  about  65°. 
By  rectifying  the  oils  of  higher  boiling  point,  a  bluish  liquid  was 
obtained  which  boiled  at  250° — 255°;  but  after  treatment  with  sodium 
the  color  disappeared,  and  the  hydrocarbon  boiled  at  255° — 258°.  It 
has  the  formula,  C10H16,  but  does  not  combine  with  dry  hydrochloric 
acid. — Journ.  Chem.  Soc,  March,  1874,  from  Deut.  Ohem.  Gfes.  Ber., 
vi,  1210. 
PYROGALLIC  ACID  AS  A  REAGENT  * 
By  M.  Schlagdenhauffen. 
The  action  of  pyrogallic  acid  upon  the  alkalies  and  the  alkaline 
earths  is  well  known.  It  forms,  with  the  caustic  alkalies,  dark-brown 
colored  compounds,  and  with  lime  water  a  splendid  violet  solution, 
which  finally  deposits  a  black  product  by  a  decomposition  not  yet  in- 
vestigated. With  the  carbonates  and  bicarbonates  analogous  results 
are  obtained.  A  few  drops  of  a  ten  per  cent,  solution  of  pyrogallic 
acid,  added  to  bicarbonate  of  magnesia  or  bicarbonate  of  lime  in  suf- 
ficiently dilute  solution  to  remain  at  first  uncolored,  gives,  after  six 
hours,  an  abundant  black  deposit.  This  reaction  the  author  has  made 
use  of  in  the  examination  of  alkaline  mineral  waters,  a  yellow  color- 
ation being  produced  at  once  in  the  water  most  impregnated  with  car- 
bonate, followed,  after  ten  or  twelve  hours,  by  a  plentiful  black  pre- 
cipitate, whilst  a  negative  result,  amounting  to  only  a  yellow  or  feeble 
brown  color,  has  been  found  to  indicate  the  absence  of  soluble  car- 
bonates. The  presence  of  calcareous  carbonates  in  potable  waters 
may  be  detected  by  adding  a  small  quantity  of  pyrogallic  acid  in 
aqueous  or  alcoholic  solution  to  a  few  cubic  centimetres  of  the  water 
to  be  examined. 
The  alkaloids  have  also  the  property  of  coloring  pyrogallol  brown, 
or  at  least  a  deep  orange  yellow,  but  the  reaction  is  not  manifest  in 
less  than  a  dozen  hours.  This  character  distinguishes  the  organic 
bases  from  neutral  crystaJlizable  bodies  and  glucosides,  the  latter  re- 
maining perfectly  inactive  in  the  presence  of  pyrogallic  acid  ;  the 
heat  of  a  water  bath  increases  the  depth  of  color.  Alcoholic  solution 
D  Union  Pharmaceutique,  vol.  xv.,  p.  5. 
