24 DR. GLADSTONE ON THE REFRACTION-EQUIVALENTS OF THE ELEMENTS. 
Gold = 3(A — OT) that is 24’0 
Rhodium .... = 3(A-j-5*2) ,, 39 - 9 
Platinum .... = 4(A — 1*6) ,, 26’0 
Assuming these to be the correct numbers, we are in a position to assign values to all 
the inorganic radicals of the salts comprised in Table VII. We have: — 
Table VIII. 
Radical. 
From the 
potassium salt. 
From the 
sodium salt. 
From the 
mean of all salts. 
Cl 
10-7 
10-6 
10-7 
Er 
170 
17 1 
1 7 0 
I 
27 0 
27-7 
27*2 
no 3 
14-0 
14-1 
14 0 
CN 
9-1 
SO, 
16-85 
17-3 
170 
S, 0., 
31 6 
322 
31-7 
H.SiO, 
22 9 
22 5 
pii,o ‘ 
19 2 
18-4 
no" 7 
112 
10 7 
Cr 0 [ 
35-3 
36-5 
35-5 
Cr.,d 7 
60-35 
65-3 
65 0 
CO, 
12-6 
12-75 
F . 
1-45 
AsO 
21-3 
SON 
25-4 
so, 
18 9 
B. 0 7 
36-3 
Mn 0. 
75-6 
FeC G N c (Ferricy.) 
77-75 
,, (Ferrocy.) 
82-3 

This Table shows that the three halogens, chlorine, bromine, and iodine, have higher 
refraction-equivalents in these mineral salts than they have in their organic compounds, 
and that the divergence increases as we advance in the series *. 
Chlorine 
Bromine 
Iodine . 
In organic compounds. 
. . 9-9 
. . 15-3 
24-5 
In mineral salts. 
10-7 
17-0 
27-2 
It also gives us additional information respecting the refraction-equivalents of some 
of the metals. 
Iron . — This metal in combination with cyanogen in the ferrocyanide and ferricyanide 
of potassium has apparently a higher equivalent than in the compounds where it plays 
the part of a base. 
Manganese . — This element exists in a highly oxidized condition in permanganate of 
potassium. If O be taken at 2-9, the refraction-equivalent of manganese will be 26-2. 
Chromium . — This also exists in combination with oxygen in the chromates and bi- 
chromates. There it has a refraction-equivalent of about 23. 
* In estimating metals from their chlorides, the equivalent 9-9 has been taken where the chloride is decom- 
posed by water, 10-7 where it is soluble without decomposition. This arbitrary distinction seems to have a 
foundation in fact. 
