534  British  Pharmaceutical  Conference.  {Am-oc°tu,ril9arm* 
As  to  the  nature  of  the  basic  hydrochloride,  Mr.  Dott  does  not  think  it  to  be  a 
mixture  or  compound  of  the  normal  hydrochloride  with  the  alkaloid,  but  that 
in  it  so  many  molecules  of  alkaloid  are  loosely  combined  with  so  many  mole- 
cules of  hydrochloric  acid,  after  the  manner  of  the  relation  of  water  of  crys- 
tallization to  a  salt  molecule. 
Lemon  Juice. — The  official  standard  of  the  citricity  of  lemon  juice  was  the 
subject  of  the  next  paper,  in  which  Mr.  T.  Howell  Williams  expressed  the 
opinion  that  this  is  now  fixed  much  too  high.  In  the  B.P.,  1867,  the  specific 
gravity  was  stated  as  1*039  and  the  contents  of  a  fluidounce  in  citric  acid  as 
32  *5  grains  ;  in  the  B  P.,  1885,  the  specific  gravity  is  given  as  1*035  to  1  "045  and 
the  citric  acid  as  36  grains  to  46  grains  to  the  fluidounce.  In  Mr.  Williams'  opin- 
ion, 30  to  36  grains  of  citric  acid  in  the  ounce  would  more  correctly  represent  the 
amount  present  in  the  lemon  juice  as  commonly  obtained  from  the  finest  im- 
ported fruit  during  the  winter  months,  and  from  20  to  30  grains  when  the  juice 
is  pressed  in  summer  and  autumn.  In  support  of  this  opinion  he  quoted  some 
memoranda  from  the  laboratory  books  of  his  firm. 
T annin :  Us  Solubilities,  etc. — Mr.  B.  S.  Proctor  recorded  a  very  large  number 
of  experiments,  undertaken  with  a  view  to  get  an  explanation  of  the  somewhat 
anomalous  behaviour  of  tannin  towards  ether.  According  to  the  B.P.,  tannic 
acid  is  only  sparingly  soluble  in  ether,  but  Mr.  Proctor  confirms  some  previous 
observers  in  the  statement  that  ether  is  really  capable  of  forming  a  solution 
with  a  relatively  large  quantity  of  that  compound.  What  appears  to  happen 
when  commercial  tannin  is  added  to  methylated  ether  is  that  after  a  time  two 
ethereal  layers  are  formed,  one  heavy  and  turbid,  and  the  other  light  and  clear, 
and  that  with  successive  additions  of  tannin  the  lower  stratum  increases  in 
bulk  and  the  upper  one  decreases  and  finally  disappears.  In  one  experiment 
this  point  was  reached  when  180  grains  of  tannin  had  been  added  to  about  235 
grains  of  ether,  and  the  liquid  then  yielded  on  filtration  a  very  small  quantity 
of  insoluble  matter  and  was  still  unsaturated.  The  experiments  were  varied  in 
many  ways,  involving  higher  rectification  of  the  ether  and  drying  of  the  tan- 
nin, but  the  nature  of  the  solution,  whether  one  of  ether  in  tannin  or  tannin 
in  ether,  or  whether  an  etherate  is  formed,  cannot  yet  be  said  to  be  demonstra- 
ted The  solubilities  of  tannin  in  water,  alcohol,  and  other  menstrua,  were 
also  given. 
Wild  Cherry  Bark. — The  next  paper,  by  Mr.  L.  W.  Hawkins,  dealt  with  the 
subject  of  the  amount  of  hydrocyanic  acid  occurring  in  wild  cherry  bark  and 
the  proportion  of  this  which  finds  its  way  into  pharmaceutical  preparations  of 
the  bark.  Six  samples  of  bark  from  leading  houses,  examined  by  distilling  the 
finely  powdered  drug  with  water  and  titrating  the  distillate  with  centinormal 
silver  nitrate  solution,  gave  results  corresponding  to  a  yield  of  hydrocyanic 
acid  ranging  from  0*079  per  cent,  to  0*160  per  cent.  The  preparations  in  use  are 
the  liquid  extract,  infusion  and  syrup  of  the  U.S. P.  and  the  tincture  of  the 
B.P.C.  Formulary.  Commercial  specimens  of  the  liquid  extract,  which  is  sup- 
posed to  represent  its  weight  of  bark,  gave  very  poor  results,  the  highest  quan- 
tity of  hydrocyanic  acid  in  any  of  six  samples  being  0  030  grams  in  100  cc,  and 
in  two  cases  none  at  all.  A  sample  made  by  the  author  strictly  according  to 
the  U.S. P.  formula  from  a  bark  containing  0*137  of  acid  only  contained  in  the 
finished  product  0*084  per  cent.,  apparently  showing  that  the  portion  of  the 
menstruum  not  subjected  to  the  influence  of  heat  is  insufficient  to  extract  the 
