VARIETIES. 
179 
quired  in  its  preparation,  will  cause  inconvenience  in  the  construction  and 
repairs  of  American  railroads. 
After  close  analysis  of  the  cost  and  details  of  the  various  systems, 
the  writer  has  been  induced  to  select  capillary  attraction  as  the  agent  for 
introducing  the  solutions  by  the  correct  way  shown  to  us  by  nature  in  the 
vegetative  process,  viz  :  by  expelling  and  following  the  sap  longitudinally, 
through  the  pores  and  tubes  of  the  timber. 
Preceded  by  a  number  of  satisfactory  experiments,  the  following  plan 
has  been  adopted : 
The  sills  are  placed  vertically  with  butt  ends  down  in  a  tightly  caulked 
rectangular  tank,  14  ft.  long,  6  J  ft.  wide,  and  8  ft,  deep,  built  of  3-inch 
plank  supported  by  upright  stays,  and  further  secured  by  transverse  bolts, 
which  prevent  the  sides  from  spreading,    (See  fig.  2.) 
When  the  tank  is  packed  with  sills,  sufficient  solution  is  added  to  fill  it 
to  the  top  of  the  sills. 
In  this  simple  apparatus,  the  pressure  of  a  column  seven  feet  in  height 
is  thus  maintained  at  the  butt  end  of  the  sill,  the  sap  is  expelled,  and  the 
preserving  solution  takes  its  place — a  tank  holding  one  hundred  sills  will 
cost  about  $70,  and  weighing  when  empty,  about  2  tons,  it  can  be  easily 
transported  to  any  part  of  the  road. 
The  number  and  kind  of  timber  operated  upon,  together  with  the  weight 
gained,  and  the  estimated  quantity  of  solution  absorbed,  are  given  in  the 
following  table :  The  sills  remaining  seven  days  in  the  tank — the  solu- 
tion consisting  of  one  part  of  pyrolignite  of  iron,  and  six  parts  water. 
