352  METHOD  OF  OBTAINING  GLUE  FROM  LEATHER. 
reaction  immediately,  perhaps,  because  these  alkaloids  sublime 
readily,  but  the  reaction  is  always  produced  eventually  when  the 
sublimate  melts  and  runs  back  again  into  the  heated  portion  of 
the  tube. 
Sulphate  of  quinine,  or  any  of  the  cinchona  bases  mixed  with 
sulphuric  acid,  are  instantaneously  colored  red  when  heated,  bur 
the  color  soon  disappears  again,  owing  to  the  energetic  action  of 
the  acid. 
Since  strychnine  yields  leucoline  when  distilled  with  caustic 
alkali  in  the  same  manner  as  the  cinchona  alkaloids,  an  experi- 
ment was  made  with  this  alkaloid  also,  but  no  red  coloration  was 
produced  either  when  it  was  heated  alone  or  with  acids.  The 
same  result  was  obtained  with  aconitine,  atropine,  berberine,  bru- 
cine,  emetine,  gentianine,  morphine,  narcotine,  salicine,  and 
theine. 
These  experiments  lead  Hr.  Grahe  to  infer  that  the  production 
of  this  red  substance,  when  the  cinchona  bases  are  heated  together 
with  organic  acids,  is  a  reaction  characteristic  of  them. 
With  regard  to  the  nature  of  the  product  thus  obtained,  it  is, 
as  might  be  expected,  very  complicated.  The  red  oleaginous 
substance  is  always  accompanied  by  an  acid  watery  liquid,  and 
has  a  peculiar  aromatic  and  empyreumatic  odor,  like  that  of  leu- 
coline and  that  of  the  cinchona  barks  combined.  When  the  red 
substance  is  left  in  contact  with  the  air,  it  becomes  brownish-red. 
Its  taste  is  bitter,  burning,  and  like  that  of  pepper.  It  is  lighter 
than  water,  to  which  it  communicates  a  slight  taste  and  smell, 
but  without  appearing  to  dissolve.  It  is  soluble  in  alcohol,  and 
water  precipitates  from  such  solution  a  soft  dark-colored  resin. — 
London  Pharm.  Jour.,  May,  1858. 
ON  A  METHOD  OF  OBTAINING  GLUE  FROM  CERTAIN  KINDS 
OF  LEATHER. 
By  John  Stenhouse,  L.L.D.,  F.R.S. 
When  the  thinner  kinds  of  ordinary  leather,  such  as  are  used 
to  form  the  upper  portions  of  boots  and  shoes,  and  for  similar 
purposes,  are  reduced  to  fine  shreds,  and  then  boiled  in  a  Papin'g 
digester,  at  a  pressure  of  about  two  atmospheres,  for  three  hours, 
with  20  per  cent,  of  powdered  chalk,  or  15  per  cent,  of  hydrate 
