510 
ON  HIVE  SYRUP  AND  ON  DIALYSIS. 
animal  skin,  or,  even  better  than  that,  vegetable  parchment ; 
which  must  be  on  the  other  side  in  contact  with  water.  When 
the  solution  of  a  crystalloid  is  put  in  the  dialyser,  the  crystalloid 
will  pass  through  the  membrane  to  the  water  on  the  opposite  side, 
while  a  quantity  of  water  corresponding  to  the  dialytic  equiva- 
lent will  stream  to  that  side  on  which  the  crystalloid  was  in  the 
commencement  of  the  operation. 
This  process  will  continue  as  long  as  solutions  on  both  sides 
are  not  of  the  same  strength. 
Colloids,  under  the  same  circumstances,  do  not  pass,  or  but 
slightly. 
In  the  above-mentioned  essay  are  the  following  lines,  page 
128,  line  8th:  "After  the  lapse  of  forty-eight  hours,  the  water 
contained  in  the  outer  vessel  will  be  found  to  have  become  quite 
thick  and  syrupy,  owing  to  the  presence  of  a  large  amount  of 
gummy  substances,  which  first  pass  through  the  porous  diaphragm, 
and,  dissolving  in  the  surrounding  water,  leave  behind  the  crys- 
talline compounds,  hardly  a  trace  of  which  can  be  found  in  the 
water,"  etc. 
From  all  this  it  is  clear  that,  in  making  the  experiment,  the 
guiding  idea  was  to  remove  by  dialysis  the  fermentatives,  as  al- 
bumen, etc.  The  error  committed  herein  was  to  suppose  that 
the  colloid  would  be  in  the  outer  liquid  after  dialysis,  while,  by 
their  inability  to  pass  through  a  septum,  they  could  only  be  found 
in  the  inner  liquid. 
The  fact  that  the  outer  liquid  was  thick  and  syrupy  proves 
that  the  white  porous  ware  employed  is  no  dialyser,  and  conse- 
quently totally  unfit  for  this  experiment. 
Mr.  G.  seems  to  have  made  the  observation  that  the  inner  and 
outer  liquid  were  not  very  different,  as  he  says,  last  line  page 
127:  "yet  still  a  large  amount  of  pectin  and  gum  refused  to 
pass  through  the  dialyser." 
By  making  the  experiment  in  the  right  manner  it  would  have 
resulted  that,  instead  of  the  thick  syrupy  liquid  he  had  outside, 
he  would  have  received  a  light-colored  one,  containing  the  most 
part  of  the  salts  and  efficacious  constituents  of  senega  and  squill, 
which  are  crystallizable,  while  on  the  inner  side  he  would  have 
had  the  extractive  and  coloring  substances,  the  albumen,  etc., 
