124  ON  THfc.   MANUFACTURE  OF  RESIN  OIL  FROM  ROSIN. 
Fremy  has  paid  much  attention  to  an  investigation  of  the  chemical 
nature  and  properties  of  resin  oil  and  the  other  products  obtained 
in  its  investigation. 
M.  Serbat,  of  St.  Saubre,  near  Valenciennes,  has  also  paid  much 
attention,  in  a  commercial  point  of  view,  to  the  manufacture  of 
this  oil,  and  particularly  of  grease  for  machinery,  the  process  for 
which  was  patented  in  France  in  1846.  In  1848,  the  Paris 
Society  for  the  Encouragement  of  the  Arts,  &c,  presided  over  by 
M.  Dumas,  made  a  report  on  this  grease,  from  which  we  extract 
the  following  : 
"  The  resin  known  under  the  name  of  black  resin  is  submitted 
to  distillation  in  suitable  apparatus,  and  the  first  products  of  the 
distillation  are  separated-  These  products  consist  of  oil,  part  of 
which  is  put  aside  to  be  employed  in  painting,  and  the  remainder 
is  used  for  making  grease. 
1.  Essential  oil  for  painting,  26  kilog. 
2.  Oil  for  grease  making,  -       -       431  kilog. 
"The  oil  obtained  by  this  distillation  is  purified  in  the  following 
manner:  All  the  oil  intended  for  making  grease  which  comes 
from  the  still,  is  poured  into  a  copper  boiler;  it  is  heated  to  the 
boiling  point,  and  allowed  to  boil  for  two  hours.  To  the  oil  is 
added  either  fragments  of  zinc  or  of  slaked  lime,  in  the  following 
proportions  : — oil,  97;  zinc,  1  ;  or  lime,  1. 
"  The  object  of  the  addition  of  these  agents,  is  :  1st,  to  separate 
the  acids  which  may  exist  in  the  resin,  or  may  be  formed  during 
the  operation.  2ndly,  to  deprive  the  oil  of  the  water  which  has 
passed  off  during  the  distillation,  and  which  volatilizes  during  the 
boiling.  The  oil  thus  boiled  is  drawn  off  hot,  and  left  at  rest  in 
copper  reservoirs,  for  a  longer  or  shorter  period,  but  in  six  hours 
afterwards  it  may  be  employed  either  in  the  preparation  of  lime- 
paste  or  of  grease.  Usually  the  oil  is  divided  into  two  portions, 
one  for  making  the  lime-paste,  and  the  other  for  conversion  into 
grease  by  the  use  of  the  lime-paste. 
"  The  reservoir  for  the  oil  must  be  furnished  with  two  taps  ;  one 
above  to  draw  off  the  oil,  and  the  other  below  to  separate  the  dregs. 
These  dregs  are  not  lost;  the  oil  contained  in  them  is  separated 
by  water  and  heat. 
Preparation  of  the  Lime  Paste. 
Take  of  slaked  lime       -       -       36  kilog. 
"     oil  ...       52  kilog. 
