Am.  Jour.  Phaim. 
Jan.,  1887. 
Ammonio-nitrate  of  Silver. 
23 
I  have  abundant  reason  to  know  that  with  ordinary  precaution  this 
process  can  be  carried  out  with  perfect  safety ;  but  that  no  departure 
should  be  made  from  the  prescribed  conditions,  and  that  especially  the 
silver  solution  should  not  be  left  about  unheeded  was  sufficiently  dem- 
onstrated by  the  circumstance  which  I  now  detail. 
To  a  solution  of  3*3  gaammes  silver  nitrate  enough  ammonia  was 
added  to  re-dissolve  the  precipitate  at  first  formed,  and  then  5 
grammes  of  pure  caustic  potash.  The  precipitate  produced  by  the 
potash  was  (nearly)  dissolved  by  a  further  addition  of  ammonia.  The 
entire  volume  of  the  liquid  was  50  cc.  It  was  inadvertently  left  in 
an  uncovered  beaker  during  nine  days,  and  on  being  then  examined 
its  surface  was  found  to  be  covered  with  a  broken-up,  lustrous,  gra- 
phitic film.  The  internal  walls  of  the  beaker  were  coated  with  a 
closely  adherent  continuous  deposit,  which  might  have  been  taken  for 
metallic  silver,  were  it  not  that  its  color  more  nearly  resembled  that  of 
the  lead-sulphide  which  is  reduced  by  sulpho-carbamide,  I  poured 
from  the  beaker  into  the  laboratory  sink  a  perfectly  clear  liquid,  but 
observing  at  the  bottom  a  nearly  black  pulverulent  deposit,  I,  in  a 
weak  moment,  turned  upon  this  a  stream  of  water  from  the  tap. 
Here  my  observations,  as  regards  any  practical  usefulness,  came  for  the 
time  to  an  end,  for  there  was  a  violent  explosion  which  so  completely 
shattered  the  beaker  as  not  to  leave  a  fragment  of  it  in  my  hands, 
which  were  somewhat  severely  cut,  and  I  was  made  deaf  for  several 
hours. 
It  was  pretty  clear  from  the  outset  that  under  conditions  not  quite 
expected,  I  had  inadvertently  produced  the  compound  of  silver  with 
ammonia  known  as  Berthollet's  fulminating  silver,  and  which 
has  also  been  viewed  as  a  nitride  of  the  metal.  These  conditions 
seemed  to  be  sufficiently  interesting  for  examination,  and  with  the 
double  object  ofdoing  this  and  of  arriving  at  the  principle  upon 
which  the  silvering  process  was  based,  I  began  a  series  of  experi- 
ments. 
That  up  to  the  present  these  have  not  been  carried  so  far  as  was 
first  intended,  is  due,  firstly,  to  the  fact  that  at  a  very  early  stage  of 
the  work  the  theory  of  the  process  became  sufficiently  intelligible  to 
render  its  further  prosecution  unnecessary,  and,  secondly,  to  a  not  un- 
natural sympathy  with  the  many  chemists  who,  though  they  have  told 
us  something  about  the  physical  characters  of  this  remarkably  treach- 
ous  explosive  compound,  seemed  to  have  unanimously  agreed  that  its 
