450 
BITTER  WINE  OF  IRON. 
The  influence  of  dryness  seems  to  be  towards  diminishing  the 
amount. 
The  influence  of  great  cold  has  not  been  tried  yet. 
The  influence  of  rain  in  hot  weather,  to  some  extent  of  course 
a  cooling  influence,  but  chiefly  a  means  of  washing  the  air,  seems 
most  decided.  After  a  thunder-storm  and  shower  at  Camden 
Square,  the  number,  which  was  previously  31,  fell  to  12. 
The  influence  of  our  towns,  especially  our  smoky  towns,  is 
most  decided  also  ;  it  is  easy  to  tell  by  this  test,  when  in  the  out- 
skirts of  a  town,  whether  the  wind  is  blowing  from  the  town  or 
the  country. 
A  distinct  difference  was  always  found  between  the  front  and 
back  of  Manchester  houses :  a  similar  difference  obtained  when 
a  room  had  been  inhabited  for  some  time,  and  the  difference  was 
of  course  very  marked  when  the  smell  of  a  sewer  came  into  the 
house.  I  had  a  good  opportunity  of  observing  this  in  my  labora- 
tory last  year. 
It  must  be  remembered  that  the  numbers  given  for  some  places 
were  obtained  on  one  day  of  the  year  only,  and  we  must  be  care- 
ful not  to  draw  too  many  conclusions  :  we  have  yet  to  learn  what 
kind  organic  matter  is  wholesome  and  what  is  unwholesome.  I 
believe  that  this  is  the  next  great  point  to  be  attended  to  ;  at 
present  we  are  only  becoming  able  to  ascertain  the  gross  amount. 
I  feel  this  caution  to  be  needful,  lest  the  numbers  should  be  used 
to  prove  too  much  London  Chem.  Graz.,  May  2,  1859. 
BITTER  WINE  OF  IRON. 
By  William  S.  Thompson. 
Having  been  requested  by  a  medical  friend  to  make  the  pre- 
paration above  named,  to  contain  one  grain  of  Wetherill's  pre- 
cipitated extract  of  bark  and  two  grains  of  citrate  of  iron  in  a 
teaspoonful  of  sherry  wine,  I  devised  th  .  following  formula,  after 
several  experiments  : 
Take  of  solution  of  persulphate  of  iron  (containing  60  grains  of 
dry  oxide  to  the  fluid  ounce,)  .      17j  fluid-drachms. 
Citric  acid,      «...        6  drachms. 
Sherry  wine,   ....      24  fluid-ounces. 
"Water  of  ammonia,  .        .        .a  sufficient  quantity. 
Wetherill's  precipitated  extract  of  bark,  224  grains. 
