300 
Current  Literature. 
Am  Jour.  Pharm. 
April,  1918. 
7H20  +  H2S04  =  ZnS0'4,  7H20  +  20H.C6H4.S03H  and  20H-- 
C6H4S03H  +  i2Br  =  2C6H2Br3 •  OH  +  6HBr.  Exactly  0.5  Grm.  of 
the  crystallized  zinc  phenolsulphonate  is  dissolved  in  water  and  the 
solution  made  up  to  500  Cc.  In  a  flask  holding  about  300  Cc.  and 
fitted  with  a  ground  stopper,  50  Cc.  of  this  solution  are  mixed  with 
50  Cc.  of  0.6  per  cent,  potassium  bromide  solution  and  50  Cc.  of 
0.1671  per  cent,  potassium  bromate  solution,  5  Cc.  of  concentrated 
sulphuric  acid  being  then  added,  and  the  flask  again  shaken  and 
left  closed  in  a  dark  place  at  about  25 0  C.  for  three  hours.  Ten  Cc. 
of  10  per  cent,  potassium  iodide  solution,  recently  prepared,  are 
next  added  and,  after  the  lapse  of  an  hour,  the  iodine  liberated  is 
determined  by  titration  with  N/10  sodium  thiosulphate.  The  num- 
ber of  Cc.  of  the  thiosulphate  used  is  subtracted  from  that  required 
in  a  blank  test  with  the  50  Cc.  of  bromide  and  5  Cc.  of  bromate 
alone  :  the  remainder,  multiplied  by  0.00447,  gives  the  weight  in 
Grms.  of  crystallized  zinc  phenolsulphonate  in  the  50  Cc.  of  solution 
taken. — G.  Adanti.  (Boll.  Chim.  Farm.,  1917,  56,  317-318;  through 
/.  Chem.  Soc,  1917,  112,  II,  517;  through  The  Analyst.) 
Detection  of  Foreign  Oils  in  Castor  Oil  used  for  Lubri- 
cating Aviation  Engines. — For  the  detection  of  foreign  oils  in 
castor  oil  the  only  method  sufficiently  sensitive  is  the  determination 
of  the  acetyl  value,  which  will  indicate  the  presence  of  1  to  2  per 
cent,  of  arachis  or  other  oils.  The  solidification-point  and  the  solu- 
bility in  alcohol  will  only  indicate  the  presence  of  5  per  cent,  of 
arachis  oil,  whilst  Bellier's  arachidic  acid  test  will  not  detect  less 
than  7.5  per  cent,  of  arachis  oil.  A  more  sensitive  test  is  to  de- 
termine the  turbidity  temperature  of  a  solution  of  1  volume  of  the 
oil  In  5  volumes  of  95  per  cent,  alcohol.  In  the  case  of  pure  castor 
oil  the  solution  can  be  cooled  below  — 200  C.  without  becoming 
turbid,  whereas  in  the  presence  of  arachis  oil  the  solution  shows  a 
turbidity  at  temperatures  varying  with  the  proportion  of  foreign  oil. 
Thus,  the  solution  of  a  mixture  of  castor  oil  with  5  per  cent,  of 
arachis  oil  becomes  turbid  at  +  6°  to  +  50  C. ;  with  4  per  cent,  at 
+  30  C,  yielding  a  copious  precipitate  at  o°  C,  with  3  per  cent,  at 
o°  C. ;  with  2  per  cent,  at  — 2°  to  — 30  C. ;  and  with  1  per  cent,  it 
becomes  opalescent  at  — 40  to  —  50  C,  and  turbid  at  — g°  C.  An- 
other method  of  detecting  and  estimating  arachis  and  other  foreign 
oils  in  castor  oil  is  to  shake  20  Cc.  of  the  sample  with  80  Cc.  of 
petroleum  spirit  (boiling  between  35 0  and  700  C.)  in  a  stoppered 
