Am  jour,  pharm.  \  Current  Literature. 
March,  1918.  J 
213 
drawn  and  the  growth  of  crystals  observed  directly  with  low  power 
without  a  coverglass ;  then  afterwards,  with  a  higher  magnification 
under  a  cover.  If  no  immediate  turbidity  is  observed,  the  tip  of  the 
stirrer  is  brought  down  to  the  surface  of  the  slide  and  stirred  against 
the  glass  in  concentric  circles  with  gentle  friction.  In  a  short  time, 
a  turbidity  will  appear  if  perchlorates  are  present,  and  in  a  couple 
of  minutes  or  so  characteristic  crystals  may  be  seen  under  the  micro- 
scope. With  strychnine  sulphate  there  will  be  group  needles  evi- 
dent with  a  1 : 1,000  solution  of  perchlorate.  With  brucine  acetate 
a  2  to  3 :  1,000  solution  of  perchlorate  is  requisite  to  obtain  charac- 
teristic lozenge-shaped  crystals.  With  morphine  hydrochloride  a 
1 : 500  perchlorate  solution  is  necessary  to  show  the  stellate  groups 
of  morphine  perchlorate.  These  reactions  are  the  corollary  of  the 
author's  micro  reactions  for  alkaloids  with  sodium  perchlorate 
reagent.  (G.  Deniges,  Annates  Chim.  Analyt.,  191 7,  22,  127,  from 
The  Pharmaceutical  Journal  and  Pharmacist.) 
Estimation  of  Silver  in  Organic  Compounds. — The  advan- 
tages of  the  cyanid-sulphide  method  are  pointed  out.  0.3  of  the 
organic  compound  are  dissolved  in  N/4  sodium  cyanide  solution, 
of  which  two  or  three  drops  are  added  in  excess.  The  solution  is 
warmed  and,  as  soon  as  the  solid  has  dissolved,  10  mils  of  N/i 
sodium  hydroxid  solution  are  added,  and  the  solution  diluted  to  300 
mils.  25  mils  of  N/4  sodium  sulphide  solution  in  excess  of  the 
theoretical  amount  required  for  the  precipitation  of  the  silver  are 
added  slowly  with  stirring,  and  the  solution  heated  to  6o°  C.  and 
stirred  until  the  precipitate  has  coagulated.  The  precipitate  is  then 
filtered  off  on  a  Gooch  crucible,  washed  with  water  until  free  from 
soluble  sulphide,  then  with  alcohol  and  ether,  and  dried  at  ioo°  to 
no°  C.  for  half  an  hour.  The  excess  of  sodium  sulphide  mentioned 
makes  certain  the  precipitation  of  all  but  0.05  Mgrm.  of  silver.  It 
is  said  by  the  authors  of  this  paper  that  in  a  number  of  instances 
in  which  this  method  was  used  most  excellent  results  were  obtained. 
(/.  Amer.  Chem.  Soc,  1917,  39,  2074-2078,  through  The  Analyst, 
Dec,  1917,  page  400.) 
J.  K.  T. 
A  Delicate  Reaction  for  Hydrogen  Peroxide. — It  has  been 
shown  that  tartaric  acid  in  the  presence  of  a  ferrous  salt  added  to 
hydrogen  peroxide,  and  the  addition  of  a  caustic  alkali,  gives  rise 
