438  Reducing  Action  of  Vaseline  and  Paraffin.    {Am^uJ™8t  Srm 
The  whole  of  No.  2  batch  of  pills  was  next  estimated.  One  dozen 
Avere  made,  and  it  was  considered  desirable  to  estimate  the  whole  of  the 
silver  nitrate  known  to  be  contained  in  them  (=  6  grains  aa=  *3888  gram), 
after  the  high  results  obtained  by  operating  on  a  portion  of  No.  1. 
The  modus  operandi  was  the  same  as  with  No.  1,  and  the  following- 
are  the  figures  obtained : 
(a)  150  cc.  silver  solution  required  6*75  cc.  NH4CNS  solution. 
(b)  150  cc.  silver  solution  required  6*7  cc.  NH4CNS  solution. 
Mean  =  4-483  cc.  NH4CNS  solution  to  completely  precipitate  100  cc.  of 
silver  nitrate  solution. 
Then  4-483  X  0171  =  '07666  AgN03  (found)  ==  98'5  per  cent. 
These  numbers  require  no  comment,  the  high  results  obtained  with 
No.  1  pills  are  probably  owing  to  the  imperfect  mixing  of  the  ingre- 
dients. Both  numbers  show  conclusively  that  the  paraffin  excipient 
has  no  reducing  action  on  nitrate  of  silver. 
In  conclusion,  Professor  Armstrong  suggests  that  part  of  the  reduc- 
tion observed  in  the  permanganate  of  potassium  may  be  due  to  a  con- 
tamination of  the  vaseline  and  paraffine  wax  with  solid  homologues  of 
the  olefine  series  (CnH2n).  On  the  other  hand  the  increase  of  over  23 
per  cent,  of  unreduced  permanganate  obtained  when  the  influence  of 
the  sandarac  coating  is,  as  far  as  possible,  eliminated,  makes  it  desirable 
to  continue  the  experiments  further  on  uncoated  pills,  or  pills  coated, 
with  melted  paraffin  mixture  only.  The  writer  finds  that  pills  coated 
with  a  mixture  of  white  vaseline  and  paraffin  wax  can  be  sugar  coated 
in  the  usual  manner  without  much  difficulty.  In  any  case,  the  fore- 
going experiments  prove  that  sandarac  coating,  or  any  organic  resinous 
coating  whatever,  is  inadmissible  with  pills  containing  permanganate 
of  potassium. 
Further  experiments  will  be  undertaken  with  permanganate,  includ- 
ing, at  the  same  time,  trials  with  authentic  specimens  of  terchloride  of 
gold,  and  the  double  chloride  of  gold  and  sodium.  If  reduction  should 
take  place,  and  appear  to  arise  from  any  impurity  contained  in  the 
vaseline  or  paraffin  wax,  then  a  process  may  perhaps  be  devised  to  get 
rid  of  this  drawback. 
My  thanks  are  due  to  Professor  Armstrong,  for  kindly  allowing  this 
investigation  to  be  carried  out  in  the  laboratory  of  the  Technical  Col- 
lege, Finsbury. — Phar.  Jour,  and  Trans.,  July  12,  1884,  p.  21. 
