A tn.  Jour.  Pharm.  V 
March,  1904.  J 
Methods  of  Water  Analysis. 
UNRELIABILITY  OF  CHEMICAL  DATA. 
There  are  a  number  of  serious  objections  to  the  data  obtained  by 
a  chemical  analysis,  (i)  Excessive  free  ammonia  in  ground  waters 
may  be  the  result,  as  has  been  mentioned,  of  the  oxidizing  action 
of  iron  or  other  metals  on  the  nitrates  present,  while  in  surface 
waters  it  may  be  produced  by  the  action  of  a  fungus  Crenothrix 
(Brown).  (2)  The  nitrites  found  in  deep-well  water  may  be  the 
result  of  the  reduction  of  nitrates  normally  present  in  the  soil  and, 
consequently,  in  no  way  represent  organic  pollution.  One  of  the 
chief  objections,  however,  is  that  a  chemical  analysis  does  not  reveal 
the  nature  of  the  organic  matter,  whether  of  vegetable  or  animal 
origin.  Admitting  that  a  certain  water  contains  an  excess  of  organic 
matter,  the  question  arises,  Does  this  organic  matter  represent 
harmless  vegetables  or  dangerous  sewage?  The  chemist  cannot 
answer  this  question  with  a  certainty  which  would  preclude  a 
u  reasonable  doubt."  Yet  a  water  contaminated  even  with  large 
amounts  of  vegetable  matter,  while  not  the  best  kind  of  water  to 
drink,  is,  nevertheless,  free  from  danger.  It  is  true,  that  if  the  am- 
monia on  distillation  is  given  off  rapidly  and  the  nitrites  and  chlorine 
are  excessive,  the  indications  that  the  organic  matter  is  derived  from 
sewage  are  reasonably  clear,  but  the  rapidity  with  which  ammonia 
even  from  animal  matter  is  given  off  is  only  comparative  and  there 
is  no  way  of  gauging  it,  while  the  excessive  amount  of  chlorine  as 
compared  with  the  normal  chlorine  standard  of  that  particular 
locality  presupposes  a  previous  study  of  unpolluted  waters  which  is 
seldom  made  and  which  often  cannot  be  made. 
The  other  objection,  one  of  a  much  more  serious  nature,  is  that 
water  may  be  organically  pure  and  yet  contain  germs  of  disease. 
Instances  are  cited  by  a  number  of  authors  showing  that  water- 
supplies  pronounced  on  chemical  evidence  to  be  above  suspicion 
have  been  proved  to  have  caused  serious  epidemics  of  typhoid  fever 
or  dysentery.  Thus  Dr.  Thresh,  in  his  well-known  book  on  "  Water 
and  Water  Supplies,"  cites  a  number  of  such  instances,  a  few  of 
which  I  will  quote. 
The  water  from  the  river  Ouse,  below  where  it  receives- the  sewage 
of  Buckingham,  to  which  an  epidemic  of  typhoid  fever  was  attrib- 
uted, was  analyzed  by  the  public  analyst,  who  reported  that  it 
"  does  not  appear  from  the  analysis  to  contain  sewage  matter." 
