'/uiy1i'i894arm*}  Solution  and  Tincture  of  Ferric  Chloride. 
323 
acid  or  ferrous  salt.  Twelve  samples  of  the  tincture  subjected  to 
similar  analyses,  save  that  the  test  for  free  hydrochloric  acid  was 
omitted,  gave  results  as  shown  in  Table  II. 
TabIvK  I. —Examinations  of  Solution  of  Ffrric  Chloride. 
Sample  No. 
Percentage 
Fe2Cl6 
Percentage 
free  HC1 
Specific 
Gravity. 
HNO3 
Ferrous 
Salt. 
1,  .... 
37  "46 
1*29 
1*397 
slight 
none 
2,  .... 
37*57 
•85 
1 '399 
slight 
3,    •  •  •  • 
36-20 
2-03 
1-387 
decided 
<  t 
4,  .... 
37-85 
1 '04 
1-405 
slight 
5,    •  •  •  • 
38-83 
1-41 
1-406 
much 
6,  .... 
38-41 
•00 
1-402 
much 
7,    .  .  .  < 
35-82 
•60 
1-367 
much 
<  < 
8,  .... 
3871 
i'35 
1-407 
slight 
9>   
34-82 
3'i9 
1-386 
trace 
<( 
10,  ... 
33-83 
•84 
i-34o 
none 
much 
Average, 
36-95 
1-26 
1-390 
Three  of  the  samples,  Nos.  6,  7  and  10,  were  made  by  retail  phar- 
macists, all  the  rest  were  made  by  manufacturing  chemists,  and 
obtained  either  directly  from  the  manufacturer,  or  indirectly  from 
the  retailer  through  the  wholesaler. 
Six  were  Baltimore  preparations,  two  New  York,  one  Philadelphia 
and  one  Detroit. 
All  the  necessary  precautions  were  taken  in  ascertaining  the  spe- 
cific gravity.  Anhydrous  ferric  chloride  was  determined  by  the 
process  given  in  the  Pharmacopoeia  of  1880,  namely:  10  grams  of 
the  solution  were  precipitated  with  an  excess  of  water  of  ammonia, 
well  washed,  dried  and  ignited,  and  weighed  as  ferric  oxide. 
Care  must  be  exercised  in  washing  the  precipitate,  otherwise  the 
percentage  of  iron  will  be  decidedly  too  high. 
The  plan  adopted  for  the  determination  of  free  hydrochloric  acid, 
and  the  tests  for  nitric  acid  and  ferrous  salt,  deserve  special  notice ; 
and  the  consideration  of  these  will,  therefore,  be  deferred  until 
later. 
Observe  in  the  preceding  table  the  approximate  relationship 
existing  between  the  specific  gravity  and  the  percentage  of  anhy- 
drous ferric  chloride,  also  that  in  most  cases  it  is  nearly  in  propor- 
tion to  that  of  the  U.S. P.    Solution  No.  4  is  practically  correct 
