154 
WOOD  SPIRIT  AND  ITS  DETECTION. 
The  separation  of  methylic  alcohol  can  be  easily  effected  by 
means  of  chloride  of  calcium,  but  other  methods  must  be 
adopted  for  the  purpose  of  investigating  the  remaining  constit- 
uents of  the  spirit. 
When  studying  the  deportment  of  various  metallic  salts  with 
the  purified  naphtha,  I  observed  the  following  reaction  : — When 
a  little  solution  of  chloride  of  mercury  was  mixed  with  a  few 
drops  of  the  spirit,  and  then  excess  of  potash  added,  the  oxide 
of  mercury  first  thrown  down  was  speedily  redissolved  with  the 
production  of  a  clear  solution.  This  result  can  be  obtained  in 
the  cold,  but  it  is  more  rapidly  brought  about  by  the  aid  of  a 
gentle  heat.  When  acetic  acid  was  added  to  the  alkaline  solu- 
tion a  yellowish-white  gelatinous  precipitate  was  formed,  but 
slightly  soluble  in  dilute  acetic,  nitric,  or  sulphuric  acids, 
though  readily  dissolved  by  hydrochloric,  which  appeared  at 
the  same  time  to  decompose  it.  The  deportment  of  this  precipi- 
tate, on  the  application  of  heat,  when  taken  in  connection  with 
other  considerations  hereafter  to  be  mentioned,  necessarily  led 
me  to  conclude  that  I  had  obtained  a  definite  compound  of  mer- 
cury with  one  of  the  constituents  of  pyroxylic  spirit. 
A  considerable  quantity  of  the  naphtha  was  now  submitted  to 
careful  distillation,  and  the  portions  which  came  over  up  to  and 
at  176°  F.  were  collected.  After  remaining  steady  at  this  tem- 
perature for  some  time,  the  boiling  point  rapidly  rose  to  1 82u  F. , 
and  this  distillate  was  likewise  collected  apart  from  the  rest. 
On  testing  the  two  portions  with  chloride  of  mercury  and  pot- 
ash, as  before  described,  the  first  distillate  gave  the  reaction 
very  strongly,  and  the  second  not  at  all.  The  more  volatile 
liquid  was  now  rectified  repeatedly  from  lime,  and  afterwards 
saturated  with  chloride  of  calcium.  The  impurities  were  then 
distilled  off  with  the  aid  of  a  water-bath  ;  and  the  liquid  which 
collected  in  the  receiver,  when  tested  as  before,  exhibited  the 
reaction  remarkably  well.  The  results  of  these  experiments 
indicate,  in  the  first  instance,  that  pure  methylic  alcohol  is  not 
connected  with  the  production  of  the  mercurial  compound  ;  and, 
secondly,  that  the  body  whose  presence  is  essential  to  the  reso- 
lution of  the  oxide  of  mercury  has  a  low  boiling-point. 
From  this  time  I  commenced  the  investigation  of  the  mercu- 
rial compound,  and  have  since  succeeded  in  tracing  it  to  its  ori- 
