66  Chemistry  of  Alkaloid  Estimations.  {AFebmaVyTi9ao8m' 
Top  milks  are  the  upper  portions  of  a  quart  bottle  of  cow's  milk 
that  has  stood  in  a  cool  place  until  a  creamy  layer  has  formed. 
They  are  obtained  with  the  use  of  the  tin  or  aluminum  dipper  de- 
vised by  Chapin.  The  dipper,  which  holds  I  fluidounce,  is  gently 
immersed  in  the  liquid,  filled,  removed,  and  the  contents  emptied 
into  another  vessel  and  mixed.  The  first  two  dippings,  mixed,  con- 
stitutes 2-ounce  top  milk  ;  or  the  first  four  dippings,  4-ounce  top  milk, 
or  the  first  eight  dippings  8-ounce  top  milk,  etc.  Little  or  no  dis- 
turbance of  the  different  layers  of  the  liquid  results  from  the  act  of 
dipping.  The  creamy  layer  usually  constitutes  about  5  or  6  fluid- 
ounces,  varying  according  to  the  original  fat  percentage  of  the  milk, 
and  the  length  of  time  standing.  It  includes,  practically,  all  the  fat 
of  the  milk.  Eight-ounce  top  milk,  or  over,  contains  not  only 
the  cream,  but  some  nearly  fat-free  milk,  also. 
The  top-milk  system  of  infant  feeding  is  rapidly  coming  into 
medical  favor.  By  diluting  top  milks  with  water,  or  with  water  and 
whole  milk,  it  is  possible  to  obtain  mixtures  for  infant  feeding  that 
contain  a  higher  percentage  of  fat  with  a  normal  percentage  of 
proteid,  than  is  possible  to  obtain  with  any  dilutions  of  cow's  milk. 
The  top  milks  are  much  superior  to  creams,  not  only  because  the 
fat  percentages  are  more  uniform,  but  also,  what  is  equally  or  more 
important,  the  dilutions  (especially  those  made  with  whole  milk  and 
water)  do  not  readily  separate  on  standing  into  strata  of  differing 
fat-percentages.  Infants  fed  with  stratified  mixtures  are  fed  an 
excessive  amount  of  fat  in  the  first  portions  of  the  food,  which  is 
just  the  reverse  of  what  obtains  in  the  feeding  of  human  milk. 
Stratification  is  especially  liable  to  occur  with  the  centrifuge  creams, 
as  these,  during  the  process  of  centrifuging,  are  partially  disorganized, 
and  hence,  mixed  with  water,  readily  stratify. 
RECENT  PROGRESS  IN  THE  CHEMISTRY  OF  ALKALOID 
ESTIMATIONS.1 
By  W.  A.  Puckner. 
While  chemistry  ranks  as  a  science,  analytical  chemistry  is  often 
spoken  of  as  the  "  art  of  analysis  "      And  this  with  some  jus- 
tice,  for  the  attention  to  details  which  a  successful  analysis  makes 
1  Read  before  the  Philadelphia  Branch  of  the  American  Pharmaceutical 
Association,  January  7,  1908. 
