234 
Atomic  Weight  Tables. 
( Am.  Jour.  Pharm. 
I        May,  1902. 
there  is  material  enough  for  all  to  do  good  work,  without  the  constant 
changes  that  will  be  necessary  if  we  insist  on  adhering  to  a  standard 
of  comparison  that  appears  tobe  but  poorly  adapted  for  the  purpose  ? 
If  we  admit  that  these  weights  are  relative  rather  than  absolute, 
would  it  not  be  just  as  well  to  use  O-16  or  C-I2  or  even  Hg-200,  as 
our  standard  of  comparison,  so  long  as  we  retain  approximately, 
within  insignificant  fractions,  the  atomic  weight  figures  with  which 
so  much  of  the  practical  work  in  chemistry  has  been  done  ?  To  the 
writer's  mind,  a  policy  of  this  kind  would  not  only  simplify  the 
routine  work  of  the  pharmaceutical,  technical  or  analytical  chemist, 
it  would  also  facilitate  original  work,  and  might  contribute  mate- 
rially to  promote  the  advent  of  that  much-to-be-desired  positive 
knowledge  of  the  constitution  and  properties  of  matter. 
U.S. P. 
U.S. P. 
Symbol 
O  =  16 
H  =  1 
1890 
1880 
Al 
27*1  ■ 
26-9 
27-04 
27- 
.  .  .  Sb 
T20' 
"9*5 
119-6 
I20* 
A 
39*9 
.   .  As 
75' 
74'45 
74-9 
74'9 
.  .  .  Ba 
137*4 
136-4 
136-9 
I36-8 
Beryllium 
.  .  .  Be 
9-1 
9* 
9-03 
9" 
.  .  .  Bi 
208-5 
206-5 
208-9 
2IO* 
ii" 
10*9 
10-9 
II' 
Br 
79-96 
79"  34 
79-76 
79-8 
Cd 
112* 
11 1*55 
111-5 
11 1  -8 
.   .  Cs 
133' 
131-9 
132-7 
132-6 
.  .  .  Ca 
40- 
39-8 
39-91 
40- 
.  C 
12' 
11-9 
11/97 
12: 
.  .  .  Ce 
140" 
138' 
139-9 
141- 
.  .  .  CI 
35-45 
35-i8 
35-37 
35*4 
Chromium    .  . 
.  .   .  Cr 
52-1 
5i'7 
52- 
52-4 
.   .  Co 
59' 
58-55 
58-6 
58-9 
Columbium  .  . 
.  .  .  Co 
94-2 
93* 
93 '7 
94' 
.  .  .  Cu 
63'6 
63-1 
63-18 
63-2 
.  .  .  Di 
142. 
144-6 
.  .  .  Er 
166- 
164-7 
166- 
165-9 
.   .  .  F 
19- 
18-9 
19- 
19- 
.  .  .  Gd 
156' 
155-8 
70- 
69-5 
69-9 
68-8 
.  .  .  Ge 
72- 
71-9 
72-3 
Au 
197*2 
I95-7 
196-7 
196-2 
He 
4' 
Hydrogen     .  . 
.  .  .  H 
i*oo8 
i- 
1  • 
1* 
In 
114- 
113-1 
113-6 
ii3*4 
.  .  I 
126-85 
125-89 
126-53 
126-6 
.    .    .  Ir 
193* 
191-7 
192-5 
192-7 
