Am 
/e0bUri8^4arm'}        Ammonium  Chloride  and  Lead  Iodide.  91 
If  at  85°  the  reading  of  the  urinometer  be  1'019,  a  correction  must 
be  made  for  25°F.,  which  will  be  25  -j-  7*25,  or  about  -0035,  and  the 
corrected  specific  gravity  will  be  1*0225. 
From  the  tables  more  exact  figures  may  be  obtained,  but  different 
specimens  vary  so  greatly  that  when  great  exactness  is  required  the 
specific  gravity  should  be  taken  at  the  standard  temperature. 
It  is  possible  that  peculiarities  in  the  diet  and  the  habits  of  different 
individuals  and  of  different  nationalities  may  produce  constant  differ- 
ences in  the  physical  characteristics  of  the  urine  as  affected  by  temper- 
ature, and  it  is  to  be  hoped  that  other  observers  will  make  a  study  of 
this  matter,  and  report  results  for  comparison.  The  figures  obtained 
in  my  own  observations  agree  very  well  with  what  we  might  expect 
from  the  composition  of  the  fluid  under  consideration.  I  have  added 
to  the  table,  for  comparison,  the  specific  gravities  respectively  of  pure 
water  and  of  a  solution  of  common  salt,  taken  at  the  same  tempera- 
tures as  the  specimens  of  urine.  It  will  be  observed  that  both  the 
saline  fluids  expand  much  more  rapidly,  especially  at  the  lower  tem- 
peratures, than  pure  water. 
ON  THE  ACTION  OF  AMMONIUM  CHLORIDE  UPON 
LEAD  IODIDE. 
By  Henry  C.  C.  Maisch. 
Read  at  the  Pharmaceutical  Meeting,  January  15,  1884. 
The  Pharmacopoeia  of  1880  gives  as  a  test  for  the  purity  of  lead 
iodide  the  following :  "  On  triturating  1  part  of  the  salt  with  2  parts 
of  chloride  of  ammonium  in  a  porcelain  mortar,  and  adding  2  parts  of 
water,  a  colorless  liquid  should  result  (absence  of  and  difference  from 
chromate)." 
This  would  give  a  solution  of  3  parts  of  the  mixed  salts  in  2  parts 
of  water.  On  looking  for  the  solubilities  I  find  the  Pharmacopoeia 
to  give  for  lead  iodide  1  part  in  2,000  parts  at  15°C.  (59°F.)  and 
in  200  parts  of  boiling  water,  and  for  ammonium  chloride  1  part  in  3 
parts  at  15°C,  and  in  1*37  parts  of  boiling  water.  The  combination 
of  the  salts  would  form,  according  to  the  pharmacopoeial  test,  a  com- 
pound soluble  in  0*67  parts  of  cold  water,  or  of  about  the  same  solu- 
bility as  the  deliquescent  salts  sodium  iodide  and  potassium  hypo- 
