433 
rotation of any rnember of the series. This residue must represent 
the value for 2 //, since. Cn ƒƒ«„_)_ o — n CH 2 = 2 H. Hence we 
may write 2 H =0.508 or the value of by drogen as 0.254. Then 
again, it is known. that CH \ = I .023, whence by deducting the value 
of 2 H we may obtain the value for carbon — 0.515. Again, when 
hydrogen is removed from a compound and replaced by chlorine, 
there is an increase in rotatory power of 1.480; hence the value 
for chlorine may be assumed to be 1.480 + 0.254 = 1.734. Similarly, 
bromine and iodine may be calculated to be equivalent to 3.562 
and 7.757 respectively. 
It has been found out that molecular magnetic rotation of elements 
is also a periodic fu.’iction of their atomic weights. 
The curve is obtained from the following data (see table p. 436) 
collected from the works of different investigators. 
