DR. GLADSTONE ON THE KEFK ACTION-EQUIVALENTS OF THE ELEMENTS. 
it open to suspicion. If, indeed, we assume 0 = 9-9, we obtain K=8-9, a higher number 
than any of the above. Considering the whole scope of the evidence, I would rather 
determine chlorine from potassium, than potassium from chlorine. 
By the second method, assuming H in water=l - 5, and in the hydracids 3 • 5 , we obtain 
from a comparison of hydrate of potassium with water K— :8T8, and from a comparison 
of the potassium salts with the hydracids Iv = 8 , 03. 
The numbers thus arrived at range from 7'6 to 8 - 7 ; but the determinations most to 
be relied on are a little above 8-0, and the whole concurrent testimony points to 8T as 
the most probable number. 
Having determined 8T as the refraction-equivalent of potassium (the A of Table VI.), 
it is perfectly simple to calculate the refraction-equivalent of every other metal in that 
Table. It is only necessary to add to, or subtract from, 8T the mean of the figures in 
each line ; but, inasmuch as some observations deserve more confidence than others, the 
exact mean was not always followed, but rather what was thought to be the most trust- 
worthy number. 
From this it results that 
Sodium 
=A— 3-3, 
that 
is 4-8 
Lithium .... 
=A— 4-3 
55 
3-8 
Caesium 
=A+ 5-6 
55 
13-7 
Rubidium .... 
=A+ 5-9 
55 
14-0 
Silver 
=A+ 7-6 
55 
15-7 
Thallium .... 
=A+13-5 
55 
21-6 
Barium 
— 2(A— Q-2) 
55 
15-8 
Strontium .... 
=2(A— 1*3) 
55 
13-6 
Calcium .... 
= 2(A— 2-9) 
55 
10-4 
Magnesium 
= 2(A— 4-6) 
55 
7*0 
Cerium 
— 2(A— 1-3) 
55 
13 6 
Didymium .... 
= 2(A-L7) 
55 
12-8 
Zinc 
= 2(A-3-0) 
55 
10-2 
Cadmium .... 
==2(A— 1-3) 
55 
13-6 
Copper 
= 2(A— 2-3) 
55 
11-6 
Iron 
= 2(A— 2T) 
55 
12-0 
Nickel 
= 2(A— 2-9) 
55 
10-4 
Cobalt 
= 2(A— 2-7) 
55 
' 10-8 
Manganese .... 
=2(A-2-0) 
55 
12-2 
Lead 
=2(A+4-3) 
55 
24-8 
Mercury .... 
= 2(A+2-0) 
55 
20-2 
Palladium .... 
=2(A+3T) 
55 
22-4 
Aluminium . . . 
= 3(A— 5-3) 
55 
8-4 
Iron 
rH 
1 
CO 
II 
55 
20-1 
Chromium .... 
= 3(A— 2-8) 
55 
15-9 
