18 The Philippine Journal of Science 1922 
The melting point of samples crystallized in water and aqueous 
solvents is undoubtedly lower than that of samples for whose 
crystallization other solvents were used. 
Capelli concludes that a melting point of 135° C. is the best 
index by which to judge the purity of this compound; tempera- 
tures of 124° to 130° are not allowed by the pharmacopceias, 
for it is believed that water retained by the sample induces 
partial saponification. 
In the samples examined we noted that only the odorless 
samples (that is to say, those free from any appreciable dis- 
sociation) possessed a high melting point, 136°C. The same 
melting point, moreover, was shown by samples having an aro- 
matic odor which was not related to either acetic or salicylic acid. 
The evaluation or the determination of the purity of a sample 
of aspirin involves two titrations in the presence of phenol- 
phthalein, according to A. Astruc,® which will show, first, its acid 
value and, second, its saponification value, thus: 
CO-OH CO-OK 
ee gS fr ey a cal + H,0 
“0-0C-CH; 
_00-0K 
+ KOH > CoH 
Non 
+ KO-OC’CHs; 
These two evaluations complete each other because the first 
titration would be insufficient if used alone Since, as Astruc 
says, if the acetylsalicylic acid were adulterated with a mixture 
of 76.66 per cent of salicylic acid and 33.33 per cent of neutral- 
ized salt, the result would be the same. Accordingly, in our 
work we determined the acid and saponification values or num- 
bers and, by way of check, we also determined the bromine 
numbers to identify the salicylic radical in aspirin, which exists 
as such or under some other form. 
Smith * assumes that acetylsalicylic acid, being so unstable a 
at nec may partially undergo molecular rearrangement in se, 
us: ” 
*Bull. Se. Pharm. 25 (1918) 79. 
"A. Nutter-Smith, Chemist and Druggist 93 (1920) 1038. 
