40 
Action  of  Pyrogallol. 
Am.  Jour.  Pharrri. 
Jan.,  1886. 
As  different  statements  have  been  made  as  to  the  physical  charac- 
ters of  nitroglycerol,  the  author  has  prepared  it  in  a  state  of  parity, 
and  finds  that  it  is  perfectly  colorless,  and  remains  so  even  when  ex- 
posed to  air.  It  keeps  equally  well  in  water  or  alcohol.  Heated  on 
the  water-bath  no  change  occurs,  unless  acids  or  alkalis  are  present. 
1  gram  of  nitroglycerol  dissolves  in  800  c.c.  water;  in  3  c.c.  alco- 
hol; in  10  5  c.c.  alcohol  (sp.  gr.  0*846) ;  in  1  c.c.  methyl  alcohol  (sp. 
gr.  0*814;  in  4  c.c.  methylated  spirit  (sp.  gr.  0*830);  in  18  c.c.  amyl 
alcohol;  in  less  than  1  c.c.  benzine;  in  120  c.c.  carbon  bisulphide  ;  in 
all  proportions  in  ether,  chloroform,  glacial  acetic  acid,  and  phenol; 
and  sparingly  in  glycerol. 
Nitroglycerol  can  be  estimated  with  tolerable  accuracy  by  deter- 
mining the  amount  of  nitrate  formed  by  boiling  with  alcoholic  potash, 
and  assuming  that  100  parts  of  nitroglycerol  yield  33* A  8  parts  of 
nitrous  anhydride. — Jour.  Chem.  Soc,  1885,  p.  742  ;  Trans.  Roy.  Soc, 
Edinb.,  vol.  32. 
ACTION   OF   PYROGALLOL  ON   COPPER  AND  IRON 
SALTS. 
By  P.  Cazeneuve  and  Q.  Linossier. 
When  solutions  of  pyrogallol  and  ferrous  sulphate  are  mixed  in 
complete  absence  of  oxygen,  no  change  is  apparent,  but  the  intro- 
duction of  a  small  quantity  of  oxygen  brings  about  the  formation 
of  the  well-known  blue  coloration.  If.  however,  the  pyrogallol 
solution  is  not  fresh,  but  has  been  slightly  oxidised,  the  blue  colora- 
tion is  produced  at  once.  The  oxygen  combines  simply  with  the 
pyrogallol,  and  does  not  oxidise  the  ferrous  sulphate,  since  ferric 
salts  cannot  exist  in  presence  of  pyrogallol,  but  are  instantly  reduced. 
A  mixture  of  a  ferric  salt  with  excess  of  pyrogallol  gives  no  colora- 
tion with  thiocyanates,  and  no  precipitate  with  ammonium  succinate. 
When  solutions  of  pyrogallol  and  ferric  chloride  are  mixed  out  of 
contact  with  oxygen,  a  fugitive  blue  coloration  is  also  produced,  but 
almost  instantly  changes  to  a  deep  reddish-brown  coloration.  Addi- 
tion of  an  alkali  causes  the  reappearance  of  the  blue  color,  and  if 
added  in  excess  changes  it  to  violet.  In  this  reaction,  the  ferric 
chloride  is  reduced,  and  the  ferrous  salt  combines  with  the  pyro- 
gallol, but  the  blue  compound  is  at  once  decomposed  by  the  hydro- 
chloric acid  which  has  been  liberated  in  the  process  of  reduction. 
