232 
Dialyzed  Mannite. 
r Am.. Jour  Phariri; 
t      May,  1881. 
large  doses  with  beneficial  effect.  Of  these  conditions  the  physician  is 
the  proper  person  to  judge,  and  we  would  not  hesitate  to  dispense  the 
large  dose  of  five  grains  of  the  extract,  as  given  by  Prof.  Bartholow; 
but  we  should  make  it  a  point  to  ascertain  that  the  attending  physi- 
cian really  intended  to  give  such  a  quantity  and  was  aware  that  it  was 
an  unusual  dose,  larger  than  the  average. 
DIALYZED  MANNITE. 
By  Louis  Genois,  Ph.G. 
Extract  from  an  Inaugural  Essay. 
Erom  its  ready  solubility  in  aqueous  liquids  and  the  large  propor- 
tion in  which  it  exists  in  the  different  mannas  of  commerce,  mannite 
is  well  adapted  for  preparation  by  dialysis.  The  accompanying  speci- 
men was  obtained  in  the  following  manner: 
Five  troyounces  of  well  selected  brittle  pieces  of  manna  were  dis- 
solved in  twenty  fluidounces  of  distilled  water  by  the  aid  of  heat ;  the 
solution  was  allowed  to  cool,  filtered,  heated  again  to  170°  F.  and 
poured  into  a  parchment  paper  covered  glass  dialyzer,  immersed  in  12 
fluidounces  of  distilled  water  heated  to  the  same  temperature  and  set 
aside.  In  24  hours  the  dialyzate  was  removed  and  replaced  by  twelve 
fluidounces  of  water  at  170°F.  and  again  set  aside;  this  was  repeated 
a  second  time,  the  contients  of  the  dialyzer  being  also  heated  each  time 
to  the  same  temperature.  The  resulting  solutions  were  mixed,  con- 
centrated at  a  gentle  heat,  filtered  and  evaporated  to  a  syrupy  consist- 
ence, and  while  still  hot  poured  into  three  equal  volumes  of  cold  85 
per  cent,  alcohol  aiid  allowed  to  rest  for  24  hours.  At  the  end  of  that 
tinie  a  considerable  amount  of  crystals,  slightly  colored,  had  deposited ; 
these  were  redissolved  in  warm  water,  the  solution  filtered  through 
animal  charcoal,  reduced  to  a  syrupy  consistence,  poured  into  cold 
alcohol,  as  before,  and  the  mixture  allowed  to  rest.  The  crystals  now 
formed  were  purified  by  solution  in  hot  alcohol,  filtration  and 
evaporation. 
The  amount  of  crystals  obtained  from  the  various  kinds  of  manna 
was : 
Large  flake,  best  quality,    .  .  .65  per  cent. 
Small    "      fair      "  .  .  26 
Sorts,  "        "         .  .  .17 
In  the  case  of  the  last  named  the  mixture  became  so  viscid  that 
dialysis  was  very  much  impeded  and  at  one  time  almost  entirely 
