20, 1 Del Rosario and Valenzuela: Acetylsalicylic Acid 21 
planation of this we venture the hypothesis, put forward by 
B. Baker,® that the more or less advanced hydrolysis and the 
amount of free acids are the reasons for such abnormality. 
STANDARD QUALITIES 
As a result of our experiments we hesitate to draw any con- 
clusions, for we realize that the climatic conditions of our 
country are perhaps responsible for the deviation of the con- 
stants of the samples, even in those considered as the best. 
As to the melting point, Jones’ says that 136° C. is the 
temperature shown by samples of stable constitution, and any 
melting point lower than 135° C. (that required by several phar- 
macopeeias) must not be accepted, for samples which have caused 
some trouble following administration to human beings have 
invariably showed the melting point to be below 133°C. In 
discussing the figures obtained by him in regard to acid and 
ester content the same author says: '° 
The question now remains as to what analytical figures may be considered 
characteristic of the best grades on the market, and the following is sug- 
gested. 
Where the acid value is greater than the ester value, that the difference 
should not exceed 0.3 cc. N/5 soda [we suppose caustic soda] per gram 
and the bromine figure should not exceed the acid value by more than 
0.15 cc. in similar terms. Where the ester exceeds the acid, the excess 
should not be more than 0.3 cc. soda per gram and in this case the bromine 
figure should not exceed the ester value. 
For free salicylic acid the limit should not be more than 0.15 per cent. 
We cannot concur in this. Our experience shows that very 
few of the samples examined would come within these require 
ments. In our opinion the quality of the aspirin depends much 
upon the technic employed in its preparation. A well-washed - 
sample is free from sulphate and chlorine ions. If it has been 
crystallized from a solvent other than water, and has then been 
thoroughly dried, its melting point will approach that of the 
pharmacopeeias, and the liability to hydrolysis will have been 
minimized. 
Nevertheless, all the requirements of purity which are valid 
in other countries should be modified after the drug has been 
subjected to our climatic conditions. All changes should be 
studied in situ, and the constants determined and required in 
* Chemist and Druggist 91 (1919) 473. ” Op. cit. 61. 
