438 
Microscopic  Notes. 
Am.  Jour.  Pharm. 
Sept.,  1890. 
It  was  slowly  and  completely  soluble  in  cold  water,  forming  a 
neutral  solution. 
A  io  per  cent,  solution  in  water  was  not  precipitated  by  an  equal 
volume  of  95  per  cent,  alcohol  ;  on  adding  ty2  volumes  it  was  partly 
precipitated,  and  3  volumes  precipitated  67  per  cent.,  which  amount 
was  not  increased  by  the  further  addition  of  alcohol.  It  was  at  first 
supposed  to  be  a  mixture  of  true  gum  and  sugar.  There  were 
found  39  per  cent,  of  total  sugar,  1 1  per  cent,  of  which  was  directly 
reducible  by  Fehling's  solution,  7  per  cent,  of  moisture,  leaving  54 
per  cent,  to  be  accounted  for  as  gum.  As  the  ash  was  only  -04  per 
cent.,  the  presence  of  that  much  acacia  was  out  of  the  question,  since 
5  or  6  specimens  of  true  acacia  were  found  to  yield  an  average  of  3 
per  cent,  of  ash.  It  was  also  found  that  longer  boiling  with  acid 
would  give  a  larger  percentage  of  sugar.  It  was  concluded  that  this 
gum  was  made  by  a  careful  treatment  of  starch  with  sulphuric  acid, 
so  as  to  partly  convert  the  former,  and  the  acid  neutralized  with 
lime,  as  the  ash  was  found  to  consist  of  calcium  sulphate. 
MICROSCOPICAL  NOTES. 
By  Hans  M.  Wilder. 
Starch. — On  heating  it  in  the  presence  of  water,  paste  will  finally 
be  formed,  but  this  formation  does  not  take  place  in  strong  alcoholic 
liquids,  fluid  resins  (for  instance,  benzol-balsam)  or  in  essential  oils,, 
heating  in  which  liquids  does  not  destroy  the  individuality  of  the 
starch  grains.  Although  cold,  moderately  strong  solutions  of 
potassa  or  soda  soon  convert  starch  into  paste,  water  of  ammonia 
apparently  exerts  no  influence.     Carbolic  acid  destroys  it  quickly. 
Experiments. — As  soon  as  the  student  of  microscopy  gets  some- 
what familiar  with  the  usual  methods  of  mounting,  he  will,  likely 
enough,  try  to  modify  them  or,  perhaps,  strike  entirely  new  paths 
— that  is  but  human  nature.  Now,  the  advice  which  the  writer 
wants  to  give  is  to  make  a  note  of  every  departure  from  the  old 
methods,  however  apparently  insignificant  it  may  seem  to  be.  The 
best  way  is  merely  to  number  each  slide,  etc. ;  and  in  a  note-book 
kept  for  this  purpose  to  enter  under  that  number  all  necessary 
remarks.  In  case  the  experiment  turns  out  to  be  a  success,  these 
remarks  will  enable  one  to  repeat  it ;  if  the  experiment  happens  to 
be  a  failure,  the  remarks  will  save  much  disappointment  and  loss  of 
