198  The  Cutting  of  Micro-sections.  {AmMay^9u>iarm' 
quire  two  or  three  hours  in  water  before  the  individual  granules 
absorb  sufficient  water  to  become  softened. 
A  tablet,  therefore,  prepared  from  material  granulated  with 
gelatine,  is  not  what,  on  superficial  observation,  it  looks  to  be;  for, 
while  it  does  break  up  readily  into  granules,  these  in  turn  do  not 
soften  rapidly,  and  consequently  ready  disintegration  and  solution 
of  the  medicinal  substance  is  out  of  the  question. 
Furthermore,  it  seems  some  manufacturers  have  gotten  into  a 
rather  routine  method  of  manufacturing  compressed  tablets,  the 
same  excipient  being  used  for  all  kinds  of  material.  It  certainly 
is  not  good  practice  to  use  dextrin  in  the  making  up  of  tablets  of 
soluble  material.  A  readily  soluble  salt  like  sodium  salicylate  does 
not  need  a  disintegrator  at  all.  In  fact,  in  such  tablets  dextrin  does 
more  harm  than  good,  because,  on  contact  with  water,  it  forms  a 
thick  starch  paste,  enveloping  the  soluble  substance  in  such  a  way 
as  to  prevent  ready  solution. 
Such  tablets  require  from  two  to  three  hours  for  solution,  while 
the  same  kind  of  tablets  prepared  without  dextrin  are  completely 
dissolved  in  fifteen  to  twenty  minutes'  time. 
To  sum  up,  then,  it  is  safe  to  say  that,  while  dextrin  is  a  good 
and  valuable  disintegrator  in  the  manufacture  of  compressed  tab- 
lets, it  should  not  be  used  indiscriminately,  and  when  it  is  used  it 
should  be  done  with  intelligence,  otherwise  more  harm  than  good  will 
be  the  result  to  the  patient,  whose  welfare  should  always  be  kept 
in  mind. 
THE  CUTTING  OF  MICRO-SECTIONS. 
By  H.  H.  Crosbie,  Baltimore. 
In  the  commercial  laboratory  where  time  is  an  important  factor 
the  cutting  of  sections  is  usually  done  by  hand,  an  operation  calling 
for  considerable  skill  and  patience.  The  microtome  of  commerce  is 
usually  to  be  found  resting  in  desuetude  on  a  top  shelf,  hand  cutting 
being  found  to  be  easier  and  quicker. 
The  instrument  illustrated  has  been  devised  and  has  been  in  use 
for  some  time,  and  we  find  it  entirely  replaces  the  skilled  hand  cutting 
previously  in  use.  As  an  instance,  one  is  able  to  cut  a  satisfactory 
cross-section  of  a  henbane  leaf  through  a  vein,  as  thin  as  0.05  milli- 
metre, with  only  a  few  minutes'  preliminary  soaking  in  warm  water. 
The  microtome  consists  of  a  brass  body  hinged  to  open  down 
