^""'jine'issr'^*}  Impurity  in  Distilled  Water.  301 
Together  with  the  nitrous  acid,  ammonia  was  found  in  unusual  quantity, 
and  the  acid  was  probably  present  in  part  at  least  in  the  form  of  am- 
monium nitrite. 
It  will  be  noticed  that  this  occurred  in  the  late  autumn,  Avhich 
agrees  with  the  recorded  fact  that  the  organic  impurities  in  water 
increase  on  the  approach  of  the  winter  months.  Nitrous  acid  in  water 
is  usually  ascribed  to  the  reducing  action  of  a  micro-organism  on  nitrates, 
themselves  produced  from  ammonia  or  combined  organic  nitrogen  by 
another  organism  of  opposite  chemical  function,  as  recently  shown  by 
Warington,  and  in  the  present  case  this  is  no  doubt  the  true  account  of 
the  matter.  But  nitrites  are  by  no  means  invariably  due  to  organisms; 
it  is  well  known  that  in  Williams's  process  for  determining  nitrates 
witli  the  copper-zinc  couple,  and  in  other  similar  methods  where  zinc 
is  used  for  reducing  them,  the  apj^earance  of  ammonia  is  preceded  by 
that  of  nitrites,  and  it  has  come  under  my  observation  that  where  a 
water  containing  nitrates  is  passed  through  some  length  of '^galvan- 
ized iron  piping,  nitrites  are  formed  in  some  quantity.  Indeed, 
wherever  nitrites  are  detected  in  a  water  it  is  always  safer  to  test  for 
zinc,  which  may  be  done  in  a  moment  with  potassium  ferrocyanide 
and  a  few  drops  of  hydrochloric  acid. 
It  is  clear  that  nitrous  acid  is  a  very  undesirable  constituent  of  dis- 
tilled water  from  a  pharmaceutical  point  of  view,  and  I  am  noAV  in  the 
habit  of  adding  to  my  still-charge  a  slight  excess  both  of  sulphuric 
acid  and  of  potassium  permanganate.  I  thus  succeed  in  destroying 
nitrites  and  keeping  back  ammonia,  and  am  able  to  provide  for  myself 
and  supply  to  my  colleagues  in  the  town  a  distilled  water  of  excep- 
tional purity,  giving  no  reaction  whatever  either  with  Nessler's  test  or 
starch  and  iodide  solution. — Pharm.  Jour,  and  Tram.,  April  11,  1885, 
p.  829. 
Sedum  acre,  Lin.,  nat.  ord.  C^rassulaceae,  is  recommended  by  Dr. 
Louis  Duval,  of  Madrid,  as  a  remedy  for  diphtheria,  a  decoction  in 
beer  being  made  of  which  a  wineglassful  is  taken  every  hour.  After 
several  doses  copious  vomiting  is  produced,  removing  the  diphtheritic 
membranes. 
This  is  the  mossy  stonecrop  of  our  gardens  and  naturalized  in  dry 
and  rocky  places  in  the  United  States.  It  formerly  enjoyed  consider- 
able reputation  as  a  remedy  in  scurvy,  drojisy,  epilepsy,  and  externally 
in  ulcers  and  various  skin  diseases.  J.  M.  M. 
