166 
ON  THE  PREPARATION  OF  PURE  SILVER. 
It  is  true  that  upon  man  small  quantities  produce  decided  symp- 
toms of  poisoning,  but,  even  after  a  somewhat  large  dose,  these 
were  not  of  such  an  alarming  character  as  to  cause  any  appre- 
hension of  a  fatal  termination.  The  author  got  about  a  hundred 
drops  in  his  mouth  and  swallowed  at  least  ten.  Violent  symp- 
toms of  poisoning  came  on,  but  not  such  as  to  cause  anxiety 
about  his  life.  In  the  arts  and  manufactures  far  more  danger- 
ous poisons  are  employed,  such  as  phosphorus,  cyanide  of  potas- 
sium, and  corrosive  sublimate.  However,  in  consideration  of  the 
injuriousness  of  nitroglycerine,  some  precautionary  regulations 
for  its  manufacture  and  sale  should  (in  the  author's  opinion)  be 
adopted.  Besides  this,  the  workmen  should  be  taught  the  dan- 
gerous nature  of  the  blasting  oil,  in  order  to  prevent  their  in- 
juring themselves  by  carelessness  in  handling  it.  If  these  means 
were  taken,  it  is  thought  that  nitroglycerine  would  scarcely  be 
found  more  injurious  than  any  of  the  other  poisons  used  in  the 
arts  and  manufactures. — London  Pharm.  Journ.,  July,  1866. 
ON  THE  PREPARATION  OF  PURE  SILVER* 
By  Professor  J.  S.  Stas. 
I  have  had  recourse  to  two  distinct  methods  to  procure  the 
pure  silver  necessary  for  the  different  purposes  treated  of  in  my 
investigations. 
First  Method. — To  carry  out  the  first  method,  I  dissolved  at 
the  boiling  point  3500  grammes  of  French  silver  coin  in  very 
dilute  nitric  acid.  The  nitrate  of  silver  produced,  after  having 
been  evaporated  to  dryness  and  fused,  was  kept  at  its  point  of 
fusion  as  long  as  oxygen  compounds  of  nitrogen  were  given  off. 
The  nitrate  mixed  with  nitrite  was  dissolved  when  cool  in  the 
smallest  possible  quantity  of  cold  water,  and  the  solution,  after 
resting  forty-eight  hours,  was  filtered  through  a  double  filter  to 
separate  all  the  matter  that  might  have  remained  in  suspension. 
The  limpid  solution*  diluted  with  thirty  times  its  volume  of  filtered 
rain-water,  was  precipitated  by  an  excess  of  pure  hydrochloric 
acid*.    The  chloride  of  silver  formed  was,  when  deposited,  washed 
*  Abstract  from  Memoirs  of  the  Royal  Belgian  Academy. 
