46 
11. ATOMIC WEIGHTS. 
TTith the single exception of the U. S. P. VIII, all of the newer 
pharmacopoeias have adopted 0=16 as the standard for atomic 
weights. 
The Ph. Austr. VIII directs that the International Standard, 
0=16, be used for the atomic weights of official chemicals. 
The Ph. Austr. VIII includes a table of the atomic weights of 
the more important elements based on H= 1.008 and 0=16. The 
pharmacopoeia also includes a table of the molecular weights, and the 
chemical formulas of the several official chemical substances. 
The introductory notes of the Pharmacopoeia, of Japan assert that 
the atomic weights, selected by the International Atomic Weight 
Committee of 1898, are adopted. A table (VII) containing names, 
symbols, and atomic weights of the more important elements is 
appended, based on 0=16 and 11=1.01. — Ph. Japon. III. p. 398. 
Leffman, Henry, asserts that by the adoption of the hydrogen 
standard for atomic weights, all quantitative measurements are put 
out of accord with those in the preparation of standard solutions, as 
given in the official bulletins of the U. S. Department of Agriculture 
and of the numerous dependent experiment stations and many ana- 
lytical manuals. 
«/- 
He also asserts that some of the tables exemplify the tendency 
to absurd and useless detail. Chemical calculations are carried out 
to the sixth decimal place, although it is well known that the atomic 
weights on which these calculations depend are not positive beyond 
the first decimal. * * * To carrv out thermometric degrees to 
the ten-thousandth is mere arithmetical gymnastics, adding to the 
expense of the book without any advantage. — Am. J. Pharm., Phila., 
1906, v. 78, pp. 80, 85. 
Coblentz. Virgil, explains that in the summer of 1900 there was 
little choice as to the standard for atomic weights. 0=16 had been 
but recently proposed for general adoption among chemists, and the 
system of H=1 had always been employed in previous pliarmacopceial 
revisions. Owing to the fact that the majority of chemists, especially 
teachers, favored the old standard, and since it was impossible to 
delay work until this matter was settled, the more conservative plan 
was adopted in retaining H=l. * * * Possibly by 1910 an agree- 
ment may be reached in accepting the 0=16 standard which gives 
figures more convenient for practical purposes. — Ibid ., v. 78, p. 303. 
Stevens. A. B., thinks it likely that if the committee were to act 
upon it at the present time they would adojit 0=16 as the standard. 
He thinks it matters little to those who use the pharmacopoeia which 
standard is selected so long as it is used throughout the entire work. — 
Proc. Michigan Pharm. Ass.. 1906, p. 95. 
