Am  Jour.  Pharm.j       AsSCLV  Processes  of   U.S. P.  IX. 
March,  19 17     J  -  J 
HQ 
The  same  method  is  followed  in  the  assay  of  oil  of  cinnamon 
as  with  caraway.  The  requirements  are  that  it  should  contain  not 
less  than  eighty  per  cent,  by  volume  of  cinnamic  aldehyde,  C9HsO. 
In  this  instance,  cinnamic  aldehyde  forms  with  the  acid  sodium  sul- 
phite an  additive  compound,  formerly  called  sodium  bisulphite  cin- 
namic aldehyde  or,  as  it  is  now  called,  sodium  cinnamalhydroxysul- 
phonate.  C6H5  ■  CH  :  CH  •  CHO  +  NaHSO,  =  C6H5CH  :  CH  •  CHO 
•NaHS03.  Under  the  influence  of  water,  the  additive  compound 
splits  up  into  cinnamic  aldehyde  and  sodium  sulphocinnamalhy- 
droxysulphonate. 
2C8H7COHXaHSOs  =  CsH7CHO 
Sodium  Cinnamalhydroxy-  Cinnamic 
sulphonate  Aldehyde 
+C6H5CH2CH(S03Na)COHNaHS03. 
Sodium  Sulphocinnamal  hydroxysulphonate 
This  latter  compound  is  soluble  in  excess  of  sodium  bisulphide. 
With  some  oils,  like  bitter  almond  and  lemon,  the  sulphite  method 
does  not  give  satisfactory  results.  In  the  new  U.  S.  P.  these  oils 
are  tested  by  the  phenyl  hydrazine  method. 
Oil  of  bitter  almond.  About  3  Gm.  of  freshly  re-distilled 
phenylhydrazine  is  dissolved  in  60  mils  alcohol,  and  25  mils  of  this 
solution  is  titrated  with  half-normal  hydrochloric  acid.  To  about 
1  Gm.  of  oil  accurately  weighed  25  mils  of  the  above  solution  is 
added  and  allowed  to  stand  one  hour,  to  form  benzal  phenylhydro- 
zone. 
C6H5NHNH2  +  C6H5CHO  =  C6H5CH-NNHC6H5  +  H20. 
Phenylhydrazine     Benzaldehyde  Benzal  Phenylhydrozone 
One  drop  of  methyl  orange  is  added  and  an  excess  of  half-normal 
HC1.  The  mixture  is  filtered  and  washed  until  it  no  longer  gives  an 
acid  reaction  to  litmus.  The  excess  of  HC1  is  titrated  with  n/2 
KOH.  Subtracting  the  number  of  mils  consumed  in  the  former 
from  the  amount  used  in  the  phenylhydrazine  test,  and  the  difference 
multiplied  by  .053  gives  the  benzaldehyde  present.  In  the  titra- 
tion of  phenylhydrazine  with  HC1,  phenylhydrazine  chloride  is 
formed.  When  the  aldehyde  is  added  to  phenylhydrazine,  phenyl- 
hydrazone  is  formed. 
Oil  of  bitter  almond  also  contains  hydrocyanic  acid,  and  its  de- 
termination is  carried  out  as  follows :  To  a  solution  of  magnesium 
sulphate  a  definite  amount  of  NaOH  is  added,  to  form  magnesium 
