394  IMPROVED  METHOD  OF  ULTIMATE  ANALYSIS. 
Hoping  I  may  have  thrown  a  ray  of  light  on  the  subject 
refered  to, 
I  remain  yours  truly, 
John  Buck.* 
Chelsea,  Mass.,  July  8th,  1854. 
IMPROVED  METHOD  FOR  CARBON  AND  HYDROGEN  DETER- 
MINATIONS IN  ORGANIC  ELEMENTARY  ANALYSIS. 
By  Edward  R.  Squibb,  M.  D.,  U.  S.  Navy. 
Assistant  Director  U.  S.  Naval  Laboratory. 
In  making  a  large  number  of  combustions  of  substances  con- 
taining nitrogen  (coal  analyses  for  technical  purposes,)  the  writer 
was  led  to  substitute  rolls  of  copper  wire  cloth  for  the  copper 
turnings  required  to  decompose  the  oxides  of  nitrogen  formed  in 
the  combustion  tube.  These  rolls  were  made  from  wire  cloth  of 
about  80  threads  or  wires  to  the  inch,  by  rolling  slips  3  inches  in 
breadth,  around  pieces  of  glass  stirring  rod  three-sixteenths  of  an 
inch  in  diameter,  till  the  size  of  the  roll  was  such  as  to  fit  easily 
into  the  combustion'tube.  The  cut  ends  of  a  few  of  the  terminal 
wires  were  then  bent  down  and  hooked  into  the  meshes  of  the  outer 
lamina  of  the  roll  to  secure  it  from  springing  open  when  out  of 
the  tube.  A  number  of  such  rolls,  sufficient  to  fill  a  long  straight 
tube  of  the  same  size  as  the  combustion  tube,  were  made  and  re- 
duced together  at  one  operation,  by  hydrogen  on  the  combustion 
furnace,  cooled  in  a  current  of  hydrogen,  the  hydrogen  displaced 
with  dry  air,  and  the  rolls  then  corked  up  in  the  tube  for  use. 
These  rolls  answer  the  purpose  quite  as  well  as  copper  turnings, 
and  are  much  more  easily,  conveniently,  and  accurately  managed, 
as  they  may  be  pushed  from  the  reduction  tube  into  the  combustion 
tube  by  a  glass  rod,  one  after  another  as  required,  without  being 
touched,  and  without  any  risk  of  acquiring  moisture  from  the 
atmosphere.  As  they  are  taken  oxidized  from  the  combustion 
tube  after  the  combustion,  they  are  returned  to  the  reduction 
tube  behind  the  reduced  rolls  till  all  have  been  used,  when 
they  are  again  reduced  together  as  before. 
[*  Note. — This  letter  was  not  intended  for  publication,  but  deeming  its 
hints  useful  to  our  readers,  we  have  taken  the  liberty  of  printing  it  here. 
—Editor.] 
