Am*Se°pUtr'i^9rm' )  U-       P-  Test  for  Methyl  Alcohol.  595 
few  observations  were  made  upon  the  influence  of  the  rise  in  tem- 
perature caused  by  the  addition  of  concentrated  sulphuric  acid,  the 
solution  being  cooled  to  room  temperature  after  each  addition  of  the 
acid,  but  the  only  difference  noted  was  that  when  cooled  the  color 
reaction  was  somewhat  retarded,  the  final  color  being  the  same,  and 
no  more  attention  was  paid  to  the  effect  of  temperature  at  the  time. 
Varying  the  quantity  of  permanganate  solution  and  the  time  of 
oxidation  had  no  noticeable  effect  upon  the  final  color. 
The  usual  result  of  the  test  for  methyl  alcohol  (when  applied  to 
ethyl  alcohol)  was  a  violet  color,  appearing  more  quickly  at  some 
times  than  at  others.  But  one  day  in  making  comparisons  an  imme- 
diate bright  red  was  obtained  which  later  faded  to  yellow,  while  two 
days  previously  the  same  solutions  and  reagents  produced,  more 
slowly,  a  violet  color.  On  the  first  of  these  two  days  the  temperature 
was  abnormally  high  and  on  the* last  it  was  lower  than  usual.  The 
temperature  of  the  laboratory  was  nearly  always  above  25 0  C,  so 
the  indications  were  that  these  experiments  had  been  made  at  too 
high  temperatures. 
Cooling  the  solution  to  25 0  C.  after  the  final  addition  of  the  acid 
was  again  found  to  be  insufficient ;  cooling  after  each  addition  of  the 
acid  produced  a  pale  violet  color  in  about  10  minutes,  which  did  not 
fade  when  the  laboratory  temperature  was  2y°-2S°  C.  When  the 
10  per  cent,  ethyl  alcohol  was  cooled  to  250  C.  before  beginning  the 
addition  of  reagents  and  cooled  immediately  after  each  addition  of 
sulphuric  acid  and  kept  at  25 0  during  the  oxidation  the  final  result 
was  a  negative  test.  Ethyl  alcohol  containing  0.25  per  cent,  methyl 
alcohol  gave  a  positive  test  when  made  at  the  same  time  and  under 
the  same  conditions,  but  not  necessarily  within  ten  minutes.  The 
time  required  will  be  referred  to  later. 
Experiments  were  made  in  which  a  more  dilute  sulphuric  acid 
was  used,  thus  avoiding  a  great  increase  in  temperature  and  allow- 
ing quicker  cooling,  but  the  results  were  not  satisfactory  because 
the  red  color  first  produced  by  the  fuchsin  T.  S.  required  consider- 
able time  to  fade.  When  concentrated  acid  was  used  and  the  solu- 
tion kept  much  below  25 0  a  pale  red  color  was  produced  which  in 
ten  to  thirty  minutes  faded  to  pale  yellow  in  the  absence  of  methyl 
alcohol,  but  in  the  presence  of  methyl  alcohol  a  violet  tint  appeared 
after  the  red  had  faded.  If  the  solution  is  kept  at  too  low  a  tem- 
perature the  results  are  not  satisfactory,  as  the  fading  of  the  red 
color  requires  too  much  time. 
