400 M. C. Lea on Numerical Relations between Equivalents. 
now we arrange the first six of these substances in parallel 
series we shall fin 
Atomic weight. Physical atoms. 
Sulphur, 32 4 
Oxygen, 16 2 
difference, 16 difference, 2 
Chlorine, 35°5 4 
Fluorine, 19 2 
difference, 16°5 difference, 2 
Phosphorus, 31 4 
Nitrogen, 14 2 
difference, 17 difference, 2 
Thus a common difference in each case amounting to 16-17 
corresponds with a difference of two of the physical atoms into 
which T'schermak divides the chemical atoms. ‘ 
w we put O=20, Cl=2cl, P=2p, the approximate differ- 
ence between S and O, Cl and F, &&., (16-17)=2A’, the dif. 
ference (48) between S and Se= A” and the difference (44-45) 
between the terms of the nitrogen series = A, we can express the 
whole of three important series in terms of these six quantities, 
so that at one and the same time both the numerical value o 
the atomic weights and the number of T'schermak’s physical 
atoms shall be correctly expressed. 
AO Symbols. At. weights. Physical atoms. 
. Oxygen group. 
Oxygen, . - 05 é eee Y “ - 2 
Sulpbur, - . + Ogle 3 32 “ - 4 
Selenium, - . og A', A" - 80 - - 5 
Tellurium, “ + og AY, 128 « - 6 
B. Chlorine group. 
luorine, . a 19 - 2 
hlorine : gate: 7 Shen ss 
ison Pe ashes 
OME ce So Ne «AT en 
C. Nitrogen group. 
itrogen, - - et - - 14 " < 
Phosphorus, - - n,A’, - 31 ee 
rsenic, : = gd ke 5°96 * +5 
Antimony, -~— - Rats iN ie Se 
