AmbJe°cU,r"i92^arm' }   Lactometer  and  Fat  in  Milk  Control.  817 
likely  that  these  compounds  are  present  from  manufacturing  de- 
fects. It  has  been  said,  however,  that  long  storage  of  the  barium 
sulphate  under  some  conditions  would  lead  to  a  reduction  of  some 
of  the  sulphate  into  the  sulphides.  That  in  the  presence  of  damp- 
ness and  organic  contaminants  certain  bacterial  agents  are  able  to 
reduce  small  amounts  of  the  sulphate  to  the  several  sulphides  is 
the  opinion  of  a  scientist  who  was  consulted  with  in  this  matter. 
Another  propounded  the  theory  that  moisture  alone  could  effect 
changes  in  the  composition  of  this  chemical. 
Summing  up,  these  facts  remain  clear.  In  the  first  place  that 
as  long  as  this  chemical  is  not  included  in  the  present  revision  cjf  the 
United  States  Pharmacopoeia  so  that  adequate  protective  tests  might 
be  consulted  and  used,  those  utilizing  this  as  their  impervious  agent 
should  be  particularly  meticulous  in  regard  to  its  source,  its  purity 
and  its  storage.  In  the  second  place,  the  product  of  reputable  manu- 
facturers should  be  specified  and  along  with  these  specifications 
should  be  added  the  designation  upon  the  order  sheet,  "Barium  Sul- 
phate, Pure,  for  X-ray  purposes."  Any  samples  giving  an  odor  of 
the  sulphides  should  be  viewed  with  suspicion  and  should  not  be 
administered  to  patients,  except  after  previously  thoroughly  washing 
in  dilute  acid  and  water.  Also  this  material  should  never  be  stored 
except  in  dry  containers  and  in  a  dry  place. 
I.  G. 
ORIGINAL  PAPERS 
LACTOMETER  AND  FAT  IN  MILK  CONTROL* 
By  David  Wilbur  Horn,  Ph.  D. 
This  paper  calls  attention  to  a  method  for  using  jointly  the 
lactometer  reading  and  the  butter-fat  content  of  a  milk  directly  as 
the  bases  for  sorting  out  skimmed,  watered,  and  sub-standard  milks. 
This  method  is  for  preliminary  use  in  routine  examinations  of  so- 
called  herd  milks  or  market  milks.  It  is  logical  that  the  lactometer 
reading  and  the  percentage  of  fat  should  serve  directly  to  guide  the 
*Read  before  the  Delaware  County  Institute  of  Science,  Media,  Pa.,  May 
9,  1921. 
