464  Researches  on  Albumin.  { Ams^ 
Volatile  Oil. — There  is  formed,  during  the  decomposition  of  albumin 
in  the  manner  under  discussion,  a  very  small  quantity  of  a  volatile  oil, 
about  1  or  2  per  cent.,  which  could  not  be  obtained  in  sufficient  quan- 
tity for  analysis  under  ordinary  conditions.  An  operation  on  the  large 
scale  with  10  kilograms  of  albumin  enabled  about  50  or  60  grams  of 
the  oil  to  be  collected,  and  an  examination  to  be  made.  It  had  no 
fixed  boiling-point;  on  account  of  the  small  quantity  at  disposal  it  was 
not  possible  to  separate  its  constituents  by  fractional  distillation.  It 
was  therefore  divided  into  four  portions  boiling  from  1130  to  120°, 
120°  to  1400,  1400  to  1800,  and  above  1800,  and  an  analysis  of  each 
portion  made.  From  the  results  of  these  analyses  the  author  is  of 
opinion  that  the  oil  is  a  mixture  of  two  substances,  one  the  more  vola- 
tile, containing  oxygen  but  not  nitrogen,  the  other  nitrogen  but  not 
oxygen.  The  presence  of  pyrrol  in  the  oil  was  clearly  established  by 
means  of  its  well-marked  reactions.  The  formula  C16H23N03  calcu- 
lates very  nearly  to  the  percentage  obtained,  from  which  if  the  formula 
of  pyrrol  be  deducted  (C4H5N)  there  remains  3(C4HgO),  which  may  be 
considered  to  represent  approximately  the  composition  of  the  remainder. 
A  small  quantity  of  a  sulphuretted  body  is  also  contained  in  the  oil.  The 
quantity  of  this  albuminol  obtainable  is  so  small  that  it  is  impossible  to 
assign  to  it  any  important  part  in  the  constitution  or  in  the  reactions 
representing  the  decomposition  of  albumin. 
The  proximate  analysis  of  the  fixed  residue  was  a  work  of  very 
great  difficulty,  and  every  method  that  could  be  devised  was  tried  with 
only  partial  success.  It  was  eventually  found  that  the  best  method 
was  to  treat  the  residue  with  neutral  solvents,  and  to  separate  the  con- 
stituents as  far  as  possible  by  means  of  fractional  crystallization.  The 
indentification  of  the  various  principles  was  afterwards  effected  by 
means  of  ultimate  analysis,  which,  in  the  absence  of  any  well  charac- 
terized reaction,  was  found  to  be  the  only  sure  or  practicable  means  of 
arriving  at  satisfactory  results.  More  than  500  combustions  were  thus 
made. 
The  two  terms  which  were  the  easiest  to  isolate  from  the  fixed  resi- 
due, on  account  of  their  slight  solubility,  were  tyrosin  and  leucin,  the 
former,  which  is  produced  to  an  extent  varying  from  2*3  to  3*5  per 
cent.,  was  recognized  by  its  crystalline  form,  and  by  its  well-known 
color  reaction  with  mercurous  nitrate  ;  the  latter  was  also  obtained  in 
