( 9°r 
ON  THE   MANUFACTURE  OF   RESIN  OIL  FROM  ROSIN.  125 
"  Heat  the  oil,  and  when  moderately  hot  add  a  portion  of  the 
slaked  lime,  which  must  be  incorporated  by  stirring  w7ith  an  iron 
spatula,  pierced  with  holes  in  the  upper  part.  When  a  portion  of 
the  lime  is  incorporated,  add  more,  by  degrees,  until  the  mixture 
is  complete. 
"  The  oil  must  be  only  moderately  heated,  for  if  heated  too  much, 
and  much  lime  be  added,  there  will  be  danger  of  frothing  up  and 
boiling  over  the  vessel.  The  boiler  in  which  the  operation  is 
performed  must  be  heated  only  at  the  bottom.  It  must  be  of  cast- 
iron  ;  the  operation  takes  about  twelve  hours.  It  is  complete  when 
the  mixture  is  become  liquid,  and  of  a  chocolate  color.  Seen  in 
the  dark  this  mixture  is  phosphorescent. 
"  This  lime-paste,  when  cold,  may  be  used  for  making  grease  ; 
it  retains  its  properties  for  an  indefinite  time." 
Manufacture  of  the  Grease. 
The  lime-paste  being  prepared,  it  must  be  kept  warm  :  and  then 
proceed  as  follows  : 
"  Take  10  kilog.  of  oil,  pour  it  into  a  small  boiler  furnished 
with  a  lip,  and  pour  into  it  (violently  shaking  it)  1  kilog.  of  the 
liquid  lime-paste.  Then  pour  the  mixture,  when  well  shaken, 
either  into  boxes  or  casks  ;  it  solidifies  with  extreme  rapidity,  and 
before  it  is  cool." 
One  can  scarcely  believe  that  it  can  be  the  addition  of  lime 
which  solidifies  the  oil,  as  the  lime-paste  is  in  a  liquid  state;  there 
is,  no  doubt,  a  particular  combination  formed.  The  grease,  thus 
solidified,  melts  when  again  heated.,  but  does  not  again  solidify. 
The  advantages  of  grease  made  in  this  manner  are  as  follows : — 
It  is  quickly  prepared  ;  its  quality  is  uniform  ;  it  does  not  soil  or 
daub  the  machines;  it  is  not  shiny;  and  does  not  increase  the 
friction. 
Resin  oil  is  much  used  in  France  in  the  manufacture  of  printing 
ink  ;  hence,  we  believe,  one  source  of  the  unpleasant  odor  derived 
from  some  of  the  French  newspapers.  Mr.  Pratt,  of  New  York, 
patented  the  application  of  resin  oil  in  place  of  linseed  and  other 
oils  in  the  manufacture  of  printing  ink  in  1848.  For  this  purpose 
one  pound  of  resin  oil,  thirteen  ounces  of  resin,  and  three  ounces 
of  yellow  soap  are  well  mixed  together  by  the  application  of  heat 
and  continued  stirring,  the  proportion  of  soap  and  resin  being  in- 
