66  Volumetric  Estimation  of  Acetone.  {^S^m*' 
based.  The  writer  examined  a  sample  of  acetone  that  contained  6 
per  cent,  of  material  (higher  ketones?)  that  possessed  a  boiling 
point  of  8o°  C.  and  above ;  yet  it  proved  on  analysis  to  contain  20 
per  cent,  of  iodoform-yielding  substances  by  our  present  methods. 
The  specific  gravity  is  of  little  value,  since  there  are  a  number  of 
products  formed  during  the  destructive  distillation  of  the  acetates 
that  possess  practically  the  same  specific  gravity  as  acetone.  An 
actual  case  will  illustrate  this  fact  admirably.  A  certain  make  of 
acetone  was  examined,  and  on  submitting  the  results  of  the  analysis 
the  producer  protested  loudly.  He  maintained  that  their  product 
contained  98  per  cent,  of  pure  acetone  according  to  the  alcoholo- 
meter. Would  methyl  alcohol  contain  98  per  cent,  of  acetone  if,  on 
immersing  the  alcoholometer,  it  sank  to  the  98  per  cent,  mark  ? 
Comment  is  unnecessary. 
The  boiling  point  is  of  considerable  value,  but  some  allowance 
must  be  made  even  for  this  constant.  A  sample,  assaying  91-96 
per  cent,  of  acetone,  yielded,  on  distilling  100  c.c.,the  following  frac- 
tions: from  55°-58°  C.  =  6  c.c;  58°-59°  C.  =  20  c.c;  59°-6o°  C. 
=  30  c.c;  6o°-62°  C.  =  25  c.c;  62°-6$°  C.  =  10  c.c;  65°-70°  C. 
=  3  c.c;  yo°  and  above  =  6  c.c.  Another  sample,  assaying  96-95 
per  cent,  of  acetone,  boiled  between  560  and  61 0  C,  with  a  small 
amount  of  residue. 
A  word  about  the  stability  of  acetone  at  this  point  may  not  be 
inappropriate.  On  assaying  a  drum  of  acetone,  it  was  found  con- 
siderably below  the  requirements.  On  informing  the  manufacturer 
concerning  it,  he  made  the  assertion  that  acetone  deteriorated  very 
materially  in  a  month.  This  information  was  quite  contrary  to  the 
writer's  experience.  For  example,  a  sample  of  acetone  had  been 
kept  by  the  writer  for  two  years,  about  one-half  of  the  time  in  a 
dark,  dry  cellar,  in  an  ordinary  greenish,  cork-stopped,  glass  bottle; 
the  remainder  of  the  time  the  bottle  and  contents  were  kept  in 
direct  and  diffused  sunlight.  This  acetone  assayed  97-12  per  cent. 
This  product  certainly  did  not  deteriorate  much  in  these  two  years; 
for  the  best  commercial  acetone  obtainable  contains  only  from  97  to 
98  per  cent,  of  pure  acetone.  Dr.  Squibb,  in  a  private  communica- 
tion, writes  thus  on  this  point :  "  Nothing  within  our  knowledge  or 
experience  has  ever  led  us  to  suspect  any  spontaneous  change  in 
acetone  by  keeping,  and  I  do  not  believe  there  is  any  such  change 
either  in  full  or  partly  filled  vessels." 
