8i6 
Barium  Sulphate. 
(  Am.  Jour.  Pharm. 
(      Dec,  1921. 
made  and  the  impervious  material  is  allowed  to  follow  the  usual 
course  of  passage  through  the  body  canals.  It  naturally  follows 
that  only  an  insoluble  and  innocuous  compound  can  be  safely  used 
for  this  purpose  because  of  the  enormity  of  the  bulk  dose  and  also 
because  of  leaving  the  material  in  the  digestive  organs  until  it  i9 
disposed  of  by  natural  processes.  Pure  barium  sulphate  is  practically 
insoluble  in  water  and  in  dilute  acids,  and  from  that  viewpoint  can 
be  used  with  impunity  for  the  stated  purpose.  Pure  barium  sulphate 
is  easily  procurable  from  the  responsible  chemical  manufacturers  if 
the  purchaser  is  satisfied  to  pay  a  slightly  increased  price,  but  there 
is  much  of  this  material  placed  upon  the  market  today  and  offered 
at  lower  figures  than  the  pure  compound  which  is  totally  unfit  for 
this  diagnostic  purpose. 
Knowing  the  comparative  toxicity  of  the  soluble  compounds  of 
barium  and  also  knowing  that  variable  and  unscientific  modes  of 
manufacturing  this  chemical  might  by  occlusion  or  otherwise  contam- 
inate the  precipitated  sulphate  with  soluble  compounds  of  barium 
or  other  bases,  the  need  for  watchfulness  and  eternal  care  in  using 
suspicious  samples  is  very  manifest. 
We  have  recently  encountered  samples  of  the  so-called  X-ray 
barium  sulphate  that  emitted  the  familiar  odor  of  hydrogen  sulphide, 
and  we  recall  one  instance  where  a  hospital  laboratory  submitted  to 
us  a  compound,  the  manufacturing  source  of  which  was  not  speci- 
fied, that  was  possessive  of  this  odor  to  an  unusual  extent.  This 
particular  sample  carried  with  it  the  reputation  of  having  caused 
much  discomfort  to  a  series  of  patients  to  whom  it  had  been  ad- 
ministered and  a  good  deal  more  discomfort  to  the  roentgenologist 
who  had  used  it.  A  cursory  examination  of  it  revealed  the  presence 
in  the  dried  material  of  about  three-tenths  of  one  per  cent,  of  water 
soluble  residue,  which  was  composed  in  the  main  of  calcium  sul- 
phate and  of  sulphides  of  zinc  and  calcium,  impurities  which  were 
probably  due  to  the  manufacturing  process.  Assuming  that  one- 
half  of  this  residue  consisted  of  the  sulphides  of  zinc  and  calcium, 
one  can  readily  see  that  a  patient  to  whom  is  administered  150 
grammes  of  the  compound  receives  of  these  sulphides  a  unit  dose 
approximating  .275  gramme,  or  about  4  grains,  a  dose  which,  while 
not  toxic,  is  at  least  nauseating. 
The  sulphides  of  barium,  were  they  present  in  a  like  propor^ 
tion  would  certainly  lead  to  more  serious  results,  but  it  is  hardly 
