oSobS;''i9^2a'°'  }       International  Atomic  Weights.  743 
flavors  they  are  supposed  to  represent.  An  actual  identification 
of  the  principal  flavoring  constituent  of  an  edible  fruit  was  ap- 
parently first  accomplished  in  1913  by  Kleber/  who  showed  by  accu- 
rate methods  that  ripe  bananas  actually  contain  amyl  acetate,  the 
substance  commonly  designated  as  *'pear  oil."  Recently  Power  and 
Chestnut^  of  the  Bureau  of  Chemistry  in  the  U.  S.  Department  of 
Agriculture  at  Washington  have  unraveled  some  of  the  mysteries 
of  the  apple.  They  obtained  no  evidence  that  amyl  valerate, 
familiarly  designated  as  "apple  oil,"  is  present  in  the  fruit.  Its 
odorous  constituents  were  found  to  consist  essentially  of  the  amyl 
esters  of  formic,  acetic  and  caproic  acids,  with  a  very  small  amount 
of  the  caprylic  ester  and  a  considerable  proportion  of  acet aldehyde. 
It  is  not  unlikely  that  some  of  the  alcohol  and  acids  mentioned  are 
also  present  in  the  free  state.  All  of  these  various  substances  occur 
in  mixtures  of  varying  proportions  in  the  numerous  varieties  of  the 
apple,  thus  giving  rise  to  slight  differences  of  odor.  The  quantities 
actually  present,  for  example,  0.0007  P^r  cent,  in  the  Ben  Davis  and 
0.0013  per  cent,  of  essential  oil  in  the  more  odorous  crab-apple, 
may  seem  small.  Nowadays,  however,  the  physician  who  deals 
with  antigens  and  antitoxins,  with  radium,  with  vaccines  and 
vitamins,  has  become  accustomed  to  the  possible  potency  of  products 
in  small  quantities. 
INTERNATIONAL  ATOMIC  WEIGHTS,  1921.* 
The  report  of  the  International  Committee  on  Atomic  Weights 
is  given  in  the  following  table : 
Atomic  Atomic 
Symbol.      Weight.  Symbol.  Weight. 
Aluminum  Al  27.1  Calcium  Ca  40 . 00 
Antimony  Sb  120.2  Carbon  C        1 2  . 005 
Argon  A  39.9  Cerium  Ce  140.25 
Arsenic  As  7496  Cesium  Cs  132.81 
Barium  Ba  137.37  Chlorine  CI  35  46 
Bismuth  Bi  208.0  Chromium  Cr  52.0 
Boron  B  10.9  Cobalt  Co  58.97 
Bromine  Br  79  92  Columbium  Cb  93  .  i 
Cadmium  Cd  112.47  Copper  Cu  63.57 
^  Kleber,  C,  Am.  Perfumer,  7:  235,  1913. 
2  Power,  F.  B.,  and  Chestnut,  V.  K.:  "The  Odorous  Constituents  of  Ap- 
ples; Emanation  of  Acetaldehyde  from  the  Ripe  Fruit,"  /.  Am.  Chem.  Soc.,^2: 
1509  (July),  1920. 
*  Journal  Amer.  Chem.  Soc,  Sept. 
