164    ON  THE  POISONOUS  CHARACTER  OF  NITROGLYCERIN. 
The  crystals,  separated  as  much 'as  possible  from  the  mother 
liquor,  and  then  fused  by  heat,  form  a  clear  and  nearly  color- 
less liquid,  slightly  more  viscid  than  usual,  which,  as  far  as  I 
have  been  able  to  ascertain,  possesses  all  the  physical  and  chemi- 
cal properties  of  pure  glycerin.  It  is  perfectly  miscible  with 
water  and  alcohol.  It  has  been  especially  tested  for  sugar  and 
glucose  (common  adulterants)  with  negative  results  :  lead  is  also 
absent,  and  nitrate  of  silver  only  produces  slight  turbidity  in  its 
aqueous  solution.  I  believe  it  to  be  almost  chemically  pure  anhy-  • 
drous  glycerin. 
Some  of  the  fused  crystals  have  been  exposed  for  several  hours 
to  a  temperature  of  0°  F.  without  solidification  taking  place. 
The  only  result  was  that  the  liquid  became  more  viscid. 
The  cause  of  the  crystallization  is  not  very  clear.  The  most 
probable  explanation  is  that  the  vibration  of  the  railway  journey 
across  Germany,  added  to  the  intense  cold  to  which  the  glycerin 
was  simultaneously  subjected,  enabled  the  particles  to  arrange 
themselves  in  a  regular  form.  The  phenomenon  then  becomes 
analogous  to  the  crystallization  of  wrought  iron  under  the  in- 
fluence of  vibration,  the  gradual  solidification  of  syrupy  solutions 
of  organic  alkaloids,  and  the  familiar  crystallization  of  refrac- 
tory platinum  salts  in  a  watchglass  by  judicious  friction  with  a 
stirring  rod.  Experiments  are  about  to  be  tried  to  see  if  the 
crystallization  of  glycerin  can  be  determined  by  exposing  it  to  a 
low  temperature,  and  at  the  same  time  setting  the  particles  in  a 
state  of  vibration. 
Should  the  above  view  of  the  cause  of  this  curious  phenomenon 
be  correct,  we  may  imagine  that,  during  the  railway  transit,  the 
vibratory  movement  was  determining  at  the  same  time  the  crys- 
tallization of  the  glycerin  and  the  railway  axles,  the  rapidity  of 
the  action  being  in  the  inverse  ratio  of  the  viscidity  of  the  two 
bodies. — London  Chem.  News,  Jan.  18,  1867. 
ON  THE  POISONOUS  CHARACTER  OF  NITROGLYCERINE. 
In  the  '  Hanoverian  Journal  for  Practical  Surgery  and  Medi- 
cine' (Zeitschrift  fur  praktische  Heilhunde  und  Medicinalwesen, 
heft  i.)  there  is  an  article  by  Mr.  B.  Schuchardt  on  the  injurious 
