244 
The  Lactometer. 
/  Am.  Jour.  Pharm^ 
t      May,  1888. 
THE  LACTOMETER  FOR  DETERMINING  THE  VALUE 
OF  MILK. 
By  Gustavus  Pile. 
The  analysis  of  milk  by  the  methods  usually  given,  although  seem- 
ing quite  simple  and  capable  of  yielding  satisfactory  results  with  but 
little  skill,  is,  however,  an  operation  requiring  considerable  care  and 
nicety  of  manipulation,  making  it  altogether  beyond  the  ability  of  the- 
general  public  and  the  dealer  to  practice.    It  would  appear  on  first 
thought  as  though  the  specific  gravity  would  afford  an  excellent 
method  for  determining  the  amount  of  solid  matter  in  the  milk,  but  on 
account  of  the  great  difference  in  the  gravities  of  the  several  constitu- 
ents it  has  proved  to  be  at  times  very  misleading ;  for  a  rich  milk,, 
containing  a  very  large  percentage  of  cream,  would  surely  give  a  spe- 
cific gravity  too  low,  the  cream  having  a  gravity  that  would  reduce  the 
whole  to  a  point  indicated  by  a  poor  sample.    Now,  in  order  to  make 
the  specific  gravity  available  as  a  basis  for  forming  a  scale  that  would 
prove  useful,  I  made  several  experiments  in  order  to  separate,  if  possi- 
ble, the  fatty  portion  by  means  of  a  solvent  and  thus  get  rid  of  the 
chief  obstacle,  but  on  account  of  the  great  emulsifying  capacity  of 
milk,  all  efforts  in  that  direction  proved  ineffectual.    An  illustration 
of  this  power  of  milk  is  seen  by  the  samples  exhibited,  where  the 
attempt  was  made  to  dissolve  the  fat  by  the  addition  of  chloroform.. 
It  was  thought  that  by  agitating  it  and  milk  together  the  fat  would 
be  extracted  and  carried  to  the  bottom  of  the  tube,  leaving  the  upper 
portion  in  a  condition  to  be  tested  for  the  amount  of  remaining  solid 
matter  by  means  of  a  hydrometer  floated  in  it.    In  one  of  the  test 
tubes,  5  cc.  of  chloroform  and  10  cc.  of  milk  are  mixed  and  not 
the  slightest  vestige  of  separation  can  be  seen  ;  in  the  other  tube  equal 
volumes  of  each  are  used  and  the  amount  of  separation  is  very  slight,, 
even  after  the  lapse  of  several  hours.    Bisulphide  of  carbon,  ether,, 
benzin,  alcohol,  and  several  mixtures  were  also  tried,  but  all  were- 
found  to  be  emulsified  to  a  degree  that  rendered  the  use  of  such  sol- 
vents entirely  useless.    The  best  method  for  effecting  the  separation 
appears  to  be  the  natural  process  of  allowing  the  cream  to  rise  to  the 
surface  and  then  drawing  it  off ;  and  while  there  will  still  be  a  portiom 
of  cream  remaining  permanently  in  the  milk,  yet,  according  to  a  number 
of  experiments,  the  percentage  appears  to  be  nearly  uniform  in  pro- 
portion to  the  amount  of  the  other  solids  and  can  therefore  be  esti- 
