822 Transactions of the Royal Society of South Africa. 
according to Barkla (Nature, March 4ith, 1915, p. 7) in which hn^,^ + hn^, + 
. . . was the energy liberated from the atom during the previous binding 
of the electron. The corpuscle spends its energy in producing more huy^, huj^ 
quanta of radiation. 
If the incident wave-length is too great to liberate a " K " corpuscle, 
then the energy absorbed from the wave per " L " corpuscle produced is 
I mv^^ + huj, + hny^ + • . • 
Por a given wave Barkla and Shearer (Phil. Mag. (6), xxx, p. 753) have 
shown that Vk = Vl. 
The fall in the constant of proportionality between Kw (absorption 
per atom) and for a given incident wave-length when the K " ring 
ceases to be excited is derived as : 
hn^^ + hnj, + hn-i^ + . . , 
hn^^ + hn-^ + . . . 
and similarly when the L " ring ceases to be excited 
/m^ -f hn^ + . • . 
hn^ + . . . 
These equations are tested with Barkla and Sadler's for the absorption 
of X-rays (Phil. Mag. (6), xxvii, p. 712) and with Bragg's results (Phil. 
Mag. (6), xxix, p. 407). Using Moseley's formula for the relationship 
between the K and L series (Phil. Mag. (6), xxvii, p. 712), and Cabera's 
formula for that between the K and M series as a check, the results are 
consistent. 
Victoria College, Stellenbosch, 
South Africa ; 
October 18th, 1916. 
