416 Scientific Intelligence. 
the atomic weights of the two constituents to be between that of 
lithium and that of hydrogen, they would both belong to the 
samerow of the periodic system, and therefore the more refrangible 
set of series would correspond to the greater atomic weight. 
For convenience of reference all the observed lines are given in 
the following table, the wave-lengths being abridged to tenth- 
metres. 
t 
Lighter Constituent. 
First Second- 
Principal series. subordinate series. subordinate series. 
20400 oe 6678 ere 7282 
5016 ee 4922 A sree 5048 
3965 A les 4388 ae 4438 
3614 Ae 4144 Bis 4169 
3448 LS afiek 4009 2h 4024 
3305 i et 3927 BAW 3936 
3297 pee! 3872 Biieat: 3878 
38258 op Aas 3834 yee 3838 
3231 ctee 3806 ee 3808 
38213 Bip 3785 a eeee 
Heavier Constituent (Heliwm proper). 
Double lines. Double lines. 
11220 eee 5876 ite 7066 
3889 ee 4472 ere 4713 
3188 ps Rae: 4026 rae 4121 
2945 ene 3820 ea be as 3868 
2829 eee 3705 para aioe 
2764 a 3634 _ SEE 3652 
2723 oe 3587 Lae 3599 
2696 et 3955 5 pat 3563 
2677 ieee 3081 Ee 3537 
3513 ue wie Bah 
3499 an es 3503 
3488 ere 3491 
3479 eae # 3482 
38472 
3466 
3461 
— Nature, lii, 521. 
3. On the specific refraction of Argon.—Dr. Gladstone read a 
paper before the British Association on specific refraction and the 
periodic law, with special reference to argon and other elements. 
In former years he had shown that the specific refractive energies 
of the elements in general were, to a certain extent, a periodic | 
function of their atomic weights. -With regard to argon, the 
specific refractive energy of argon gas as reckoned by Lord Ray- 
leigh’s data is 0'159. At the suggestion of Deeley, the bearing of 
