172 
Dairying  in  Denmark. 
the  box,  the  cream  gradually  accumulating  in  the  centre  of  it. 
After  a certain  time  the  box  becomes  full  of  cream,  when  the 
machine  is  stopped  and  the  cream  flows  out  through  the  same 
tube  as  that  which  carried  off  the  skim-milk  while  it  was  in 
motion.  A small  quantity  of  cream  clings  to  the  floor  of  the 
collector,  and  is  carried  away  by  the  first  portion  of  skim-milk 
after  each  stoppage  of  the  machine,  whilst  upon  opening  the 
machine  to  clean  it,  after  the  whole  of  the  milk  has  been  dealt 
with,  this  adhering  remnant  of  cream  must  be  washed  out  care- 
fully with  skim-milk.  A structural  peculiarity  of  the  drum  of 
this  machine  consists  of  three  horizontal  plates  extending  almost 
to  its  circumference,  and  turning  with  it.  These  plates  are 
said  to  facilitate  the  separation  of  the  cream,  to  aid  in  keeping  it 
inside  the  drum  while  it  is  in  motion,  and  at  the  same  time  to 
facilitate  the  exit  of  the  skim-milk.  The  speed  at  wrhich  this 
machine  is  driven  is  said  not  to  exceed  1200  revolutions  per 
minute. 
The  remaining  separator  to  be  noticed  differs  essentially 
from  all  others  in  having  its  plane  of  revolution  vertical  instead 
of  horizontal.  The  drum  is  very  thin  in  proportion  to  its 
diameter,  and  contains  a ring  of  metal  perforated  in  two  places. 
The  milk  enters  the  interior  of  the  ring,  and  is  there  partially 
separated  by  the  rotatory  motion  going  on,  so  that  the  partly 
skimmed  milk  first  enters  the  drum,  where  a final  and  complete 
separation  takes  place.  The  skim-milk  passes  through  two 
small  tubes  into  an  outer  ring,  and  is  there  brought  into  contact 
with  a spoon  terminating  in  a pipe,  by  which  means  it  is  drawn 
off.  A similar  arrangement  draws  the  cream  from  the  centre  of  the 
drum,  and  by  varying  the  length  and  diameter  of  the  two  small 
tubes  previously  mentioned,  the  greater  or  less  completeness,  of 
the  separation  may  be  regulated.  The  action  is  thus  exactly  the 
same  in  principle  as  that  of  the  Danish  separator,  but  the  position 
of  the  drum  is  at  right  angles  to  it. 
If  it  be  wished  to  stop  the  machine,  as  much  of  the  cream  and 
skim-milk  as  is  possible  is  drawn  off  by  the  spoons  and  their 
pipes,  and  the  supply  of  milk  having  been  stopped  they  are 
removed.  The  aperture  of  the  drum  is  then  closed  by  a 
cover,  which  can  be  pressed  against  the  face  of  it  w'hile  it  is 
still  in  motion,  and  fits  so  as  to  be  quite  air-tight.  The  speed 
causes  a small  vacuum  in  the  drum,  so  that  when  the  motion  is 
stopped,  the  skim-milk  in  the  outer  ring  rushes  back  into  the 
interior  of  the  drum.  These  machines  are  very  large,  powerful, 
and  somewhat  costly,  but  it  is  claimed  for  them  that  they 
require  for  the  work  done  only  one-half  the  proportionate  power.* 
* For  an  illustration  of  this  machine,  see  vol.  xviii.,  l’art  II.  of  the  2nd  series 
of  this  Journal,  p.  621. 
