56      CHALK  IN  BUTYRIC  AND  LACTIC  FERMENTATIONS,  ETC. 
I  have  verified  these  results,  and  found  them  always  the  same. 
I  must  add  that,  under  the  same  conditions,  pure  carbonate  of 
lime  has  no  action,  provided  all  contact  with  air  be  avoided  ; 
but  there  are  cases  in  which  creosote  does  not  prevent  these 
mixtures  fermenting,  which  would  make  it  appear  that  there  are 
in  the  air  adult  organisms  capable  of  existing  in  a  creosotic 
medium  containing  lime. 
I  will  add  two  observations  :  the  first  is,  that,  to  prevent 
chalk  from  acting  either  on  cane-sugar  or  starch,  it  should  be 
moistened  and  heated  to  about  300°  ;  the  second  is,  that,  if 
sufficient  precautions  be  taken,  there  will  be  found,  after  fer- 
mentation, no  other  ferment  than  that  observed  in  the  chalk, 
though  this  will  have  augmented. 
II.  ChaUc  contains  carbon,  hydrogen,  and  nitrogen  in  the  state 
of  organic  matter. — If  the  preceding  experiments  be  really  con- 
clusive, organic  matter  ought  to  be  found  in  chalk.  To  demon- 
strate tin's,  I  have  submitted  to  organic  analysis  the  insoluble 
part  left  by  chalk  when  treated  by  dilute  acids. 
Dissolve  an  unpulverized  block  of  chalk  in  weak  hydrochloric 
acid.  Collect  the  undissolved  portions  on  strong  and  smooth 
paper,  and  wash  them  in  acidulated  water  until  no  lime  is  de- 
tected in  the  filtrate.  Then  remove  the  moist  residue  with  a 
card,  without  injuring  the  filter ;  spread  it  thinly  on  a  sheet  of 
glass,  and  let  it  dry  screened  from  dust. 
100  grammes  of  chalk  will  thus  give  1-15  gr.  of  insoluble  por- 
tions dried  at  100°.  By  then  drying  at  about  160°,  and  in- 
cinerating, it  will  be  found  that  100  parts  of  residue  dried  at 
100°  are  formed  of — 
Per  ct. 
Water  (lost  at  100°  to  160°),  .  .  .  2-47 
Organic  matter  (lost  by  incineration,  .  7*17 
Mineral  matter  (residue),         .        .        .  90*36 
100-00' 
Submitted  to  organic  analysis,  the  residue  dried  at  100°  fur- 
nished the  following  results : 
Carbon,      ~   1-053 
Hydrogen,  0-740 
Nitrogen,  0428 
