172  Chlor amine  Reactions  of  Proteins.    {Amj/a0r"h  ^ V™' 
counteracting  this  alkalinity  by  the  addition  of  a  weak  acid.  It 
must,  however,  be  pointed  out  that  part  of  this  reputed  alkalinity 
of  the  hypochlorite  solution  may  really  be  the  result  of  the  chlora- 
mine  reaction.  It  is  certainly  the  case  that  a  solution  of  sodium 
hypochlorite  adjusted  to  complete  neutrality  by  titration  still  feels 
strongly  "  caustic "  to  the  hands.  This  is  explained  by  reference 
to  the  original  reaction  RNH2  +  NaOCl  =  RNHC1  +  NaOH. 
Whenever  a  chloramine  is  formed  from  a  neutral  hypochlorite, 
caustic  alkali  is  liberated,  and  it  would  be  interesting  to  ascertain 
whether  this  equation  is  capable  of  affording  a  volumetric  analytical 
method.  Alkali  acts  to  a  certain  extent  as  a  stabilizing  agent  on  the 
chloramines,  and,  on  the  other  hand,  when  a  neutral  chloramine  de- 
composes, hydrochloric  acid  is  liberated  according  to  the  reaction 
3RNHC1  =  N2  +  RNH2  +  3HC1.  From  these  two  equations  the 
advantage  in  surgical  work  of  the  addition  of  a  polybasic  acid,  such 
as  boric  acid,  capable  of  giving  amphoteric  salts,  becomes  very 
obvious. 
In  our  technical  investigations  we  paid  special  attention  to  the 
chloramine  reactions  of  gelatin  as  typical  of  the  group,  depositing  it 
on  cotton  yarn  as  an  aqueous  solution,  and  fixing  it  in  the  form 
of  insoluble  chloramine.  This  treated  yarn,  after  thorough  wash- 
ing, still  retained  the  active  chlorine  reaction.  Previous  combina- 
tion with  formaldehyde  did  not  affect  the  normal  course  of  the 
reaction.  If  a  cake  of  dry  gelatin  is  steeped  in  a  hypochlorite  solu- 
tion for  several  hours  the  outside  is  converted  into  a  hard  layer  of 
insoluble  chloramine,  but  the  gelatin  swells  in  the  ordinary  manner. 
If  it  be  then  washed  and  transferred  to  hot  water,  the  gelatin  of 
the  interior  dissolves  and  is  liberated  by  puncturing  the  outer  skin, 
leaving  an  empty  bag  of  gelatin  chloramine.  It  is  possible  that  this 
phenomenon  might  be  utilized  in  diffusion  experiments,  and  the 
chloramine  membrane  might  exhibit  special  semipermeable  effects. 
When  the  gelatin  chloramine  is  dried  in  the  oven  it  is  decomposed 
with  the  evolution  of  gas  and  development  of  free  hydrochloric  acid. 
As  a  qualitative  test  for  localized  deposits  of  proteins  the  chlora- 
mine reaction  is  unexcelled.  Stains  of  protein  fluids  on  fabrics,  the 
presence  of  wool  fibers  in  cotton,  the  presence  of  glue  or  casein  in 
adhesives  and  coatings,  are  easily  demonstrated  by  chlorinating, 
washing,  and  developing  the  color  reaction  with  potassium  iodide 
and  starch.  The  most  minute  fragment  of  the  sample  will  suffice 
for  the  test,  and  in  special  cases  the  original  sample  of  fabric  may 
