A%?a°rchj9oirm'}    Recent  Literature  Relating  to  Pharmacy.  141 
millimetres  pressure,  and  forming  a  crystalline  semicarbazone, 
melting  at  21 2°  C.  On  oxidation  with  chromic  acid  the  aldehyde 
yielded  santalic  acid.  H.  V.  A. 
THE  CHARACTER  OF  DROPS. 
An  interesting  contribution  to  this  subject  is  an  article  by  F. 
Eschbaum  [Ber.  Dtsch.  Ph.  Ges.,  1900, 91).  He  gives  table  of 
weights  of  drops  of  almost  every  kind  of  liquid,  and  from  his 
experiments  has  deduced  the  following  equations : 
(1)  To  secure  uniform  drops  it  is  necessary  that  the  liquid  drop 
from  a  spherical  surface  of  estimated  radius.  He  shows  that  the  in- 
fluence of  the  surface  of  the  vessel  from  which  the  liquid  is  dropped 
comes  from  the  readiness  of  this  surface  to  form  a  curved  segment 
of  liquid,  which  the  investigators  call  the  meniscus  of  the  drop. 
This  aggregation  of  liquid  continues  to  collect  on  the  dropping  sur- 
face of  the  container  until  its  adhesive  power  is  overcome  by  the 
force  of  gravitation,  hence  the  actual  formation  of  the  drop  is  solely 
influenced  by  cohesion  and  gravitating  force.  For  instance,  he 
finds  that,  taking  two  tubes  of  the  same  calibre,  one  of  which  is 
very  thin  walled,  the  thicker  the  wall,  the  larger  the  drop;  in  other 
words,  the  outer  circumference  of  the  dropping  surface  is  the  sole 
determinant  of  the  size  of  the  drop.  This  continues  with  in- 
creased circumference  of  tube  until  the  maximum  of  a  drop 
of  water  is  attained.  This  maximum  drop  he  finds  weighs  0-2330 
grammes. 
(2)  The  weight  of  a  drop  of  a  mixture  of  two  liquids  is  always 
between  the  weight  of  its  two  components. 
(3)  The  weight  of  a  drop  of  a  solution  of  a  solid  body,  such  as 
salts,  bases,  acids,  extractive  matter,  and  also  of  a  solution  of  a  gas, 
is  practically  the  same  as  that  of  its  solvent.  In  this  connection  the 
writer  discovered  an  interesting  fact,  that,  usually,  the  weight  of  a 
drop  of  a  saturated  solution  of  a  salt  is  less  than  that  of  a  drop  of 
water. 
(4)  That  the  rapidity  of  dropping  from  the  same  container,  or 
variation  in  temperature  during  dropping,  while  exerting  a  certain 
influence,  is  not  sufficient  to  be  considered  in  practical  work. 
(5)  The  size  of  a  drop  varies  according  as  the  liquid  is  dropped 
from  a  full  bottle  or  from  one  partially  full. 
Dropped  from  a  tube  of  diameter  6  63  millimetres,  measured  from 
