518 
SOLUBILITY  OF  GLUE  IN  GLYCERIN. 
Bower*s  inodorous  glycerin,  spec.  gr.  1*25  ;  the  glue  had  been 
softened  on  the  surface,  the  pieces  had  become  adhesive,  and  the 
liquid  contained  notable  quantities  of  gelatine  in  solution,  readily 
proven  by  the  flocculent  precipitate  occurring  with  solution  of 
tannin,  the  results  being  exactly  the  same  as  in  the  first  portion 
of  experiment  No.  2. 
White  glue  was  now  soaked  in  water  until  it  had  become  soft, 
the  water  was  drained  off  and  Bower's  inodorous  glycerin  added 
(No.  9).  Thus  far  no  change  has  been  produced  in  the  appear- 
ance of  the  glue. 
The  results  of  these  experiments  may  be  summed  up  as  fol- 
lows : 
1.  Glue  is  soluble  at  the  ordinary  temperature  in  a  large  pro- 
portion of  glycerin. 
2.  Glue  is  permeable  by  glycerin,  slowly  at  ordinary,  more 
readily  at  an  elevated  temperature. 
3.  Glue  swelled  in  consequence  of  the  absorption  of  water, 
remains  unchanged  in  appearance  under  glycerin,  that  is  to  say, 
even  if  the  glycerin  should  abstract  the  water,  the  former  will 
take  the  place  of  the  latter  liquid,  thus  preventing  the  shrinking 
of  the  glue. 
4.  Glue,  by  continued  digestion,  dissolves  completely  in  gly- 
cerin, gelatinizing  on  cooling. 
5.  The  solution  of  glue  in  glycerin  is  accelerated  by  previous 
maceration  in  glycerin,  and  by  increasing  the  temperature 
(doubtless  also  by  increasing  the  pressure). 
6.  Glue  thoroughly  permeated  by  water  dissolves  in  hot  gly- 
cerin about  as  readily  as  it  does  in  hot  water. 
It  appears  to  me  that  the  behavior  of  gelatin  and  glycerin  to 
unite  to  a  jelly  of  any  desirable  consistence  might  probably  be 
made  use  of  in  medicine  as  a  vehicle  for  medicines  of  an  un- 
pleasant taste.  The  antiseptic  properties  of  glycerin  would, 
doubtless,  render  such  a  jelly  perfectly  unchangeable,  while  its 
non  drying  qualities  would  retain  to  the  jelly  its  soft  consistence. 
Of  course  there  is  no  difficulty  in  imparting  to  such  a  prepara- 
tion any  desirable  flavor. 
In  analysis  gelatin  is  used  to  estimate  the  quantity  of  tannin 
contained  in  astringent  vegetables,  many  of  which  are  used  for 
