450  British  Pharmaceutical  Conference.  {K£lvl^^S: 
With  regard  to  the  characters  of  the  pilocarpine  salts,  the  author  thinks  that 
the  nitrate  should  consist  of  permanent  white  crystals,  soluble  in  6  or  7 
parts  of  water  and  146  parts  of  95  per  cent,  alcohol,  fairly  soluble  in  boiling 
alcohol  but  almost  insoluble  in  ether  or  chloroform.  When  heated  in  a  capil- 
lary tube  the  salt  should  melt  at  1760  to  1780,  and  its  specific  rotatory  power 
in  aqueous  solution  should  be  +  8i°  to  +  830.  No  residue  should  be  left  on 
ignition,  and  there  should  be  no  precipitate  on  adding  ammonia  water,  or 
sodium,  or  potassium  hydroxide  to  a  concentrated  aqueous  solution.  The 
hydrochloride  should  form  deliquescent  crystals,  soluble  in  less  than  their  own 
weight  of  water,  and  in  10  parts  of  absolute  alcohol,  but  almost  insoluble  in 
ether  or  chloroform.  The  dried  salt  should  melt  at  2000  to  2040,  and  its  specific 
rotatory  power  should  be  -f  900  to  +  920.  No  residue  should  be  yielded  on 
ignition,  and  a  concentrated  aqueous  solution  should  give  no  precipitate  with 
ammonia  water,  and  only  a  few  oily  drops,  which  quickly  redissolve,  on  the 
addition  of  sodium  or  potassium  hydroxide. 
DELPHINIUM  STAPHISAGRIA. 
By  E.  M.  Holmes. 
The  author  directs  attention  to  the  fact  that  the  true  Delphinium  Staphisa- 
gria  is  practically  unknown  in  botanic  gardens  of  England,  and  that  the  plant 
which  passes  under  that  name  is  really  another  species,  viz.,  D.  pictutn,  Willd. 
The  difference  between  these  two  species  is  given  in  detail  in  the  paper. 
THREE  NATURAL  RUBBER  SUBSTITUTES. 
By  David  Hooper. 
The  author  describes  three  elastic  gums  which  have  been  suggested  as  rub- 
ber substitutes.  The  first  is  obtained  from  the  stem  of  Ficus  bengalensis,  and 
dissolves  without  previously  swelling  in  ether,  chloroform  and  carbon  disul- 
phide.  It  contains  a  large  proportion  of  resins.  The  second  is  the  product  of 
Calotropis  gigantea  and  C.  procera,  and  contains  but  little  caoutchouc.  The 
third  substance  is  the  coagulum  of  the  milky  juice  of  Exccecaria  azallocha, 
Linn.  It  possesses  irritating  properties,  and  that  fact,  conjoined  with  the 
presence  in  the  substance  of  alcohol-soluble  resins,  contraindicates  its  fitness 
to  serve  as  a  rubber  substitute.  None  of  the  three  substances,  in  fact,  appears 
suitable  for  that  purpose. 
THE  LIBERATION  OF  C02  FROM  SODIUM  BICARBONATE  BY 
HEAT. 
By  C.  S.  Dyer. 
In  this  paper  the  author  deals  with  the  liberation  of  carbon  dioxide  from 
sodium  bicarbonate  when  heated,  and  doubts  the  accuracy  of  Cowie's  state- 
ment that  the  salt  decomposes  at  a  temperature  between  500  and  6o°  C.  In 
his  opinion,  the  detection  of  traces  of  carbon  dioxide  by  a  delicate  test  on  ex 
posing  a  bicarbonate  to  a  temperature  of  about  550  C.  is  not  sufficient  evidence 
that  the  salt  decomposes  at  that  temperature  to  any  practical  extent,  and  he 
asserts  that  dry  sodium  bicarbonate  scarcely  decomposes  at  all  below  6o°  C,  only 
slowly  below  ioo°  C,  but  rapidly  above  120°  C. 
