ELECTRICAL  PROPERTIES  OP  PYROXYLIN  PAPER,  ETC. 
293 
form,  or  some  other  fluid  containing  chlorine  mixed  with  the 
fluid  called  chloroform,  as  that  is  got  by  the  B.  P.  and  other 
processes.  That  last  supposition  is  not  likely  to  be  the  truth^ 
but  whether  it  be  so  or  not  it  still  leaves  potassium  inadmissible 
as  a  test ;  for  whatever  the  fluid  is,  it  is  produced  according  to 
the  given  formula.  Our  belief,  however,  is  that  chloroform 
is  one  fluid,  and  that  it  is  decomposed  both  by  Potassium  and 
Sodium. 
How  the  error  has  arisen  we  cannot  say,  but  the  authors  of 
the  «  British  Pharmacopoeia '  are  not  singular  in  their  belief  as 
to  the  non-evolution  of  gas  from  chloroform  by  the  action  of 
Potassium  ;  for  Liebig,  as  quoted  in  Grtnelin,  says  that  chloro- 
form distilled  over  Potassium  is  not  decomposed;  and  Heintz 
also,  as  quoted  by  Watts  in  his  4  Dictionary  of  Chemistry,' 
states  that  chloroform  is  not  decomposed  by  Sodium  even  when 
%  heated  with  it  in  a  sealed  tube  to  200°  Centigrade.  In  the  ex- 
periment made  before  you,  Sodium  decomposes  it  at  natural 
temperatures  as  you  have  seen,  and  so  also  does  Potassium. 
The  only  other  matter  worth  mentioning  is,  that  the  crust 
formed  on  the  Na  is  not  wholly  NaCi ;  it  gives  up  something 
not  yet  examined  to  dry  alcohol, and  effervesces  on  the  addition  of 
HC1,  and  is  strongly  alkaline  to  litmus-paper.  Ic  is,  when  got 
of  a  grey  color  and  in  fine  powder,  soluble  in  water,  giving  a 
brown  saline  substance  when  again  evaporated  down.  Heated 
to  redness  it  is  soluble  in  water,  and  leaves  in  the  filter  a  small 
quantity  of  what  looks  like  charcoal,  and  its  solution  effervesces 
more  on  the  addition  of  acid  than  it  did.    These  last  facts  point 
to  the  formation  of  an  organic  acid  London  Pharm.  Journal, 
May,  1865. 
ON  THE  ELECTRICAL  PROPERTIES  OP  PYROXYLIN 
PAPER  AND  GUN-COTTON. 
By  Prof.  J.  Johnson. 
(In  a  letter  to  Prof.  Silliman,  dated  Middletowu,  Conn.,  January  25,  1865.) 
You  did  me  the  honor,  a  year  ago,  to  publish  in  the  Journal 
a  note  of  mine  on  the  electrical  properties  of  pyroxylin  paper 
and  gun-cotton^  adding  an  approving  note  of  your  own.  Hav- 
ing lately  had  opportunity  to  make  some  further  experiment? 
with  the  same  substances,  I  herewith  send  you  the  result. 
