NITRIC  ACID. 
63 
culiar  appearance.  The  ends  nearest  the  corroded  parts  of  the 
fabric  were  stained  of  a  deep  brown  or  black ;  but  for  some  little 
distance  beyond  the  blackened  portion  the  fibre  was  colored  of 
a  pale  yellow  hue,  as  if,  during  the  decomposition  of  the  silver 
salt  that  had  been  employed  as  "  marking-ink,"  the  nitrogenous 
constituents  of  the  tissue  had  been  partially  acted  upon  and  con- 
verted into  xanthoproteic  acid. 
Between  several  of  the  fibres,  and  in  many  places  adhering  to 
their  external  surfaces,  were  found  small  particles  of  some  or- 
ganic tissue,"  which  were  colored  of  a  still  deeper  yellow  than  the 
fibres  themselves.  On  subjecting  some  of  the  latter  to  the  ac- 
tion of  strong  liquor  ammonia,  the  yellow  portions,  particularly 
the  altered  intercellular  substance,  acquired  a  still  darker  hue, 
whilst  those  on  the  contrary,  which  were  stained  by  the  reduced 
silver,  became  somewhat  paler,  as  if  a  portion  of  the  argentine 
film  were  soluble  in  that  menstruum ;  though  it  should  be  observed, 
that  no  further  effect  was  produced  on  the  stain  even  by  a  pro- 
tracted digestion  in  ammonia.  Now,  upon  making  comparative 
experiments  with  a  piece  of  the  linen  wrapper  that  had  been  re- 
cently "marked"  in  the  usual  way  with  a  solution  of  nitrate  of 
silver,  the  fibres  were  found  to  present  a  very  similar  appearance 
to  that  before  described ;  the  only  difference  being  that  the  yel- 
low coloration  was  not  quite  so  distinct,  and  more  of  the  silver- 
stain  was  removed  by  the  solution  of  ammonia  ;  whereas  on  the 
other  hand,  fibres  that  had  been  stained  by  solutions  of  chloride 
and  oxide  of  silver  in  ammonia  were  uniformly  colored  of  a  dark 
brown  or  black,  and  exhibited  no  trace  of  yellow  coloration. 
These  results  conjoined  with  the  corroded  state  of  the  linen  in 
the  vicinity  of  the  marks,  justify  us,  I  think,  in  concluding  that 
the  ancient  Egyptians  were  really  acquainted  with  nitric  acid  ; 
and,  as  my  father  has  already  suggested,  employed  the  nitrate  of 
silver  as  a  marking-fluid.  In  what  manner,  however,  they  pre- 
pared the  acid,  whether  by  the  distillation  of  the  nitrate  of  soda 
or  nitrate  of  potash  with  oil  of  vitriol,  or  by  one  of  the  pro- 
cesses adopted  by  the  alchemists,  I  will  not  at  present  attempt 
to  decide,  but  will  leave  the  problem  to  be  solved  at  some  future 
period,  when  the  researches  of  antiquarians  shall  have  offered  us 
further  evidence  on  the  subject  Annals  of  Pharmacy,  from 
Philo sopl deal  Magazine, 
