Ammonium  Benzoate. 
f  Am.  Jour.  Pharm. 
\    January,  1910. 
Table  III  are  perhaps  more  clearly  exhibited  by  the  following- 
graphic  representation.  The  lower  curve  shows  the  temperatures 
at  which  the  various  mixtures  began  to  melt — the  beginning  of  the 
melting  being  understood  as  that  point  at  which  the  sample  col- 
lapses or  sinks  down  in  the  capillary,  or  that  point  at  which  the 
first  definite  trace  of  liquid  can  be  detected.   The  upper  curve  repre- 
TABLE  III. 
MELTING  POINTS  OF  MIXTURES  OF  AMMONIUM  BENZOATE  AND  BENZOIC  ACID 
Sample 
Per  cent,  composition 
C6H5COONH4  C6H5C00H 
I 
la 
Nil 
III 
IV 
V* 
VI* 
VII* 
VIII* 
IX* 
X* 
A 
Aj 
B 
5-73 
5-73 
3-85 
Trace 
Trace 
Trace 
Trace 
Trace 
1.2 
6.4 
8± 
ii. 8 
2C5± 
43- 
5o.i7 
5o-i7 
79- 
94.27 
94.27 
96.15 
97.8 
100.0 
Melting 
or  decomposition 
point  (cor.) 
5°  to 
.2°tO 
0  to 
,I°tO 
.8°  to 
,i°to 
.7°  to 
^to 
'°tO 
192 
188 
*93 
I93 
193 
*93 
191 
i92.9°to 
190.4 
190.7 
194 
189 
194 
194 
194 
194 
J93 
194 
192 
I93 
i88.6°to  192 
187.  i°  to  192 
183. 90  to  190 
152. 0  to  177 
Remarks 
121. 30  to  122. 30 
to  148. 90 
12 1 .3°  to  131. 50 
to  149. 0 
120. 8°  to  121. 30 
to  146. 90 
I2I.3°tO  121.8° 
121. 40  to  122. 40 
Vigorous  effervescence. 
Effervescence  after  5  to  7  min. 
Vigorous  effervescence. 
Vigorous  effervescence. 
Vigorous  effervescence. 
Vigorous  effervescence. 
Vigorous  effervescence. 
Vigorous  effervescence. 
Effervescence. 
Slight  melting  and  efferves- 
cence. 
Last  trace  effervesces  slightly. 
Slight  effervescence  finally. 
Heated  very  slowly  from  175. 
Definite  sign  at  1 20-1 21  but 
no  liquid  until  152;  no  effer- 
vescence. 
Most  melts  1 2 1-2 ;  no  efferves- 
cence. 
C  remelted  after  cooling. 
Behavior  similar  to  C. 
Melts  without  decomposition. 
Melts  without  decomposition. 
*  Samples  VII  and  IX  represent  degree  of  decomposition  of  two  samples 
of  ammonium  benzoate  as  a  result  of  standing  in  an  ordinary  desiccator 
over  sulphuric  acid  for  about  2\  months.  Samples  V,  VI,  VIII,  and  X  were 
obtained  by  subjecting  a  sample  of  pure  ammonium  benzoate  to  vacuum 
desiccation  (about  50  mm.  Hg),  in  the  presence  of  sulphuric  acid  for  6,  42, 
112,  and  184  hours  respectively. 
sents  the  final  reading — not  necessarily  the  point  of  complete  lique- 
faction, for  in  all  cases  where  80  per  cent,  or  more  ammonium  ben- 
zoate was  present  the  effervescence  was  sufficiently  vigorous  to 
drive  the  material  up  the  tube  and  in  those  cases  the  final  reading 
represents  the  point  of  vigorous  effervescence.  The  distance  between 
