352 
The  Nature  of  Solution. 
/Am.  Jour.  Pharro. 
1       July,  1891. 
power  of  reducing  ammoniated  nitrate  of  silver.  This  reagent  is 
prepared  by  adding  diluted  ammonia,  drop  by  drop,  to  asolution-of 
nitrate  of  silver  until  the  precipitate  shall  be  entirely  redissolved, 
but  adding  no  more  than  this.  If,  into  the  above  solution  we  pass  a 
few  bullae  of  oxide  of  carbon,  the  liquor,  without  heat,  becomes 
quickly  of  a  brownish  color  ;  with  ebullition  there  forms  an  abun- 
dant black  precipitate.  The  reaction  likewise  takes  place  with  an 
aqueous  solution  of  oxide  of  carbon.  As  the  reagent  is  very  sensi- 
tive and  will  operate  in  the  presence  of  atmospheric  air,  it  may  be 
used  to  ascertain  the  presence  of  traces  of  oxide  of  ca-rbon  in  gaseous 
atmospheres,  provided  no  other  reductive  substance  be  present. 
Nitrate  of  Strontium. — In  the  R'epert  de  Phar.  of  May  ioth, 
Dr.  Boutron,  a  professor  in  the  Nantes  School  of  Medicine  and 
Pharmacy,  writes  as  follows  in  confirmation  of  Dr.  Laborde's  state- 
ments as  to  the  innocuousness  of  strontium  salts  (see  Am.  Jour. 
Phar.,  1 89 1,  p.  129)  :  "  In  1885,  when  I  was  in  the  service  of  Dr. 
Vulpian  at  the  Hotel-Dieu  he  gave  to  a  patient  suffering  from  acute 
articular  rheumatism,  25  gm.  {that  is  to  say,  twenty-five  grammes} 
daily,  of  nitrate  of  strontium.  The  treatment  was  continued  for 
about  two  months  and  did  not  appear  to  cause  the  least  inconve- 
nience to  the  patient.  It  was  withdrawn  because  it  ceased  to  have 
further  action,  and  was  replaced  by  salicylate  of  lithium  in  doses  of 
5-50  gm.  daily. 
THE  NATURE  OF  SOLUTION. 
An  answer  has  long  been  sought  to  the  question,  "  What  goes  on 
when  a  solid  substance  is  dissolved  by  a  liquid  ?"  Those  who 
received  their  course  of  didactic  instruction  a  good  many  years  ago 
were  taught  that  the  solid  substance  was  liquefied.  It  was  said 
that  the  particles  of  a  fusible  salt,  such  as  nitre,  for  instance,  could 
be  brought  into  the  liquid  condition  by  one  of  two  methods ;  the 
first  that  of  applying  heat,  heat-energy  being  used  up  in  the  process 
of  liquefaction ;  the  second  process  being  that  of  submitting  the 
body  to  the  action  of  water,  when  the  absorption  of  heat  due  to 
liquefaction  was  shown  by  the  lowering  of  temperature.  This 
explanation  of  the  process  of  solution  has  been  long  since  found 
unsatisfactory,  and  in  more  recent  years  teachers  have  preferred  to 
say  as  little  as  possible  about  a  process  in  appearance  so  simple, 
but  of  which  the  explanation  was  found  to  be  encompassed  with 
