166 
VARIETIES. 
1.  Gray  metal  gives  more  satisfactory  results  than  white  metal,  which  is 
moreover  too  brittle. 
2.  Magnets  tempered  at  alow  red  heat  lose  all  their  magnetism  in  twenty, 
four  hours. 
3.  They  retain  their  magnetism  perfectly  when  tempered  at  a  bright  red 
heat. 
The  following  is  the  method  of  obtaining  the  maximum  magnetic  power. 
The  bars  are  heated  to  a  red  heat  in  a  blast  furnace  ;  they  are  taken  out, 
and  powdered  over  the  two  faces  for  f  ths  their  length  with  the  yellow  prus- 
siate  of  potash  pulverized,  and  then  are  plunged  immediately  into  a  large 
quantity  of  cold  water,  with  violent  agitation.  When  the  bars  are  eooled, 
they  are  magnetized  by  means  of  a  horse  shoe  electro-magnet  capable  of 
lifting  about  200  kilograms.  The  two  poles  of  the  magnet  are  applied  at 
the  place  where  the  branches  of  the  cast  iron  magnet  become  parallel ;  the 
poles  are  made  to  slide  quite  to  the  extremities  of  the  branches,  and  then 
detached  to  repeat  3  or  4  times  the  same  process  of  friction.  After  operating 
thus  upon  one  of  the  faces,  the  other  is  subjected  to  the  same  treatment, 
taking  care  that  the  same  poles  are  brought  into  contact  with  the  same 
branches. 
The  poles  of  the  bundle  of  cast  iron  magnets  ought  to  be  always  kept  in 
contact  with  an  armature  of  wrought  iron  of  a  size  proportional  to  that  of 
the  bundle.  The  bars  of  east  iron  should  be  a  little  thicker  than  those  of 
steel. — Ibid. 
Mode  of  obtaining  Camphor  from  Oil  of  Sassafras.  By  M.  Faltin. — 
M.  Faltin  found  that  during  the  action  of  chlorine  gas  upon  oil  of  sassafras, 
the  latter  becomes  converted  into  a  thick  tough  mass,  whilst  a  large  quantity 
of  hydrochloric  acid  is  formed.  After  neutralization  with  milk  of  lime,  this 
mass  furnishes  on  distillation  a  small  quantity  of  camphor,  which  is  per- 
fectly identical  in  its  properties  and  composition  with  common  camphor. 
It  could  only  be  obtained  from  the  oil  by  the  action  of  chlorine.  It  is  proba- 
bly produced  from  the  unoxygenated  oil  contained  in  the  oil  of  sassafras. 
This  observation  therefore  possesses  some  interest,  as  the  Sassafras  tree 
belongs  to  the  Laurineaz,  the  same  family  which  includes  the  Japanese 
camphor- tree. —  Chem.  Gaz.  Nov.  1853,  from  Ann.  der  Clum.  wid  Pharm.T 
Ixxxvii.  p.  376. 
Patent  granted  to  P.  Warren,  for  a  Substitute  for  Papier-maeM,  &e. — This 
invention  consists  in  manufacturing  a  new  material  or  composition  of  a 
character  analogous  to  papier-mache,  which  is  capable  of  being  employed 
either  as  a  substitute  for  papier-mache  or  gutta  percha,  and  its  compounds^ 
in  forming  or  manufacturing  various  articles  for  which  these  substances  are 
now  used,  such  as  panels  and  mouldings  for  railway  carriages,  trays,  picture 
and  other  frames,  door  knol)s,  buttons,  &c,  by  treating  the  straw  of  any 
fibrous  vegetable  material  hereinafter  described.    In  order  to  carry  out  this 
