Am.  Jour.  Pharm.  ) 
Aug.  1,  1873.  J" 
The  Preparation  of  Gelaiiji* 
369 
filled  with  pure  hydrogen,  about  half  a  litre  of  the  mixed  gases  was 
sent  through  the  apparatus,  the  induction-coil  not  being  in  action  ; 
the  bulb  containing  the  acid  was  then  removed  and  another  substi- 
tuted, containing  an  equal  volume  of  the  same  acid. 
About  half  a  litre  of  the  mixed  gases  was  now  passed  through  the 
apparatus,  submitting  them  to  the  action  of  the  electricity.  The 
contents  of  the  two  bulbs  were  next  transferred  to  two  test-tubes;, 
and  after  adding  excess  of  potash  to  each,  Nessler's  test  was  applied. 
The  first  solution  gave  a  faint  yellow  coloration,  the  second  a  rather 
thick  reddish-brown  precipitate. 
No  attempt  was  made  to  estimate  the  quantity  of  ammonia  formed, 
•as  it  would  vary  with  many  of  the  conditions  of  the  experiment. 
Since  writing  the  account  of  the  above  experiment,  which  was  made 
in  Dr.  Odling's  laboratory  at  Oxford  on  March  24, 1  have  seen  in  the 
"  Comptes  Rendus  "  for  April  22,  1873,  a  note  of  an  experiment  by 
Messrs.  Thenard  of  Paris,  in  which  they  observe  the  formation  of 
traces  of  ammonia  by  the  action  of  electricity  on  a  mixture  of  hydro- 
gen and  nitrogen  ;  but  no  details  of  the  mode  of  operating  are  given. 
■ — Pharm.  Journ.  and  Trans.,  London,  June  21,  1873. 
THR  PREPARATION  OF  GELATIN. 
In  the  ordinary  manner  of  making  light-colored  gelatin,  thin  skins, 
sinews,  cartilages  and  bones  are  employed,  which  must  be  treated 
with  muriatic  acid  and  lime  before  being  dissolved.  These  have  fur- 
nished a  good  article,  but  at  a  high  price.  The  expense  of  this  pro- 
cess therefore  induced  F.  Henze,  of  Berlin,  to  thoroughly  investigate 
the  subject  of  its  manufacture  in  the  hope  of  producing  an  equally 
good  article  at  a  lower  price.  The  material  employed  was  the  brown, 
or  almost  black,  glue  of  very  poor  quality,  which  is  a  by-product  in  a 
Berlin  neatsfoot  oil  manufactory,  and  which  sells  for  five  dollars  per 
hundred  weight.  This  substance  does  not  swell  up  in  cold  water  like 
glue,  but  forms  a  gummy  mass,  dissolving  as  a  thick,  syrupy  liquid, 
not  very  adhesive,  but  resembling  that  of  which  printers'  rollers  are 
made.  It  is  now  used  only  in  making  cardboard  and  as  a  dressing 
for  very  dark-colored  fabrics. 
In  preparing  this  glue,  the  feet  are  first  freed  from  hoofs  and  the 
more  solid  bones  of  the  leg,  which  are  used  for  turning  into  buttons 
and  ornaments,  and  washed.    They  are  then  exposed  for  three  hours 
24 
