734 Proceedings of Royal Society of Edinburgh. [sess. 
complex ions exist in solution, whereas in the case of certain 
“double nitrates” there was little evidence to show the existence 
of such complex ions. 
Some such result might especially have been expected in the 
case of the alums, whose formula agrees with that of type B. 2 and 
may reasonably be expected to be some modification of it. 
Moreover, Recoura has shown* that the “anhydrous” alums 
belonging to that type can be obtained from the ordinary alums by 
the application of heat. The existence of complex ions in the salts 
of the monobasic acids, as shown by their conductivities, agrees 
perfectly with the constitutions which I have assigned to such salts. 
A similar series of compounds exists in the case of quadrivalent 
elements; and to illustrate this, a table including the complex 
chlorides, fluorides, sulphates, and oxalates of tin, thorium, 
titanium, and uranium, is appended.! 
Type A. has been again chosen to represent the “saturated” 
compounds, B. those in which one hydroxyl group remains un- 
replaced, and so on. 
1 
HC1 
HF 
H 2 S0 4 
h 2 c 2 o 4 
A. 1. 
2. 
Sn ; (Cl 2 ) 4 : Pt 
Sn:(F 2 .NH 4 ) 4 
Sn : (C 2 0 4 ) 4 • Ba 2 
C 2 0 4 :[Sn:(C 2 0 4 .K) 3 ] 2 
Sn B. 2. 
Cl 2 : Sn(Cl 2 .M) 2 
F 2 : Sn : (F 2 .M) 2 
C. 1. 
(HO) 2 : Sn : (C 2 0 4 .M) 2 
A. 1. 
Th:(Cl 2 ) 4 :Pt 
Th;(S0 4 .M) 4 
Th j (C 2 0 4 .Na) 4 
Th B. 2. 
Fo : Th : (F 2 .K) 2 
S0 4 : Th : (S0 4 .M) 2 
C. 2. 
Cl 3 :Th.Cl 2 .K 
fs ! Th.F 2 .M 
Ti B. 2. 
Cl 2 :Ti :(C1 2 .NH 4 ) 2 
F 2 : Ti : (F 2 .K) 2 
S0 4 : Ti : (S0 4 .K) 2 
C. 1. 
(H0) 2 : Ti : (S0 4 .NH 4 ) 2 
(H0) 2 :Ti:(C 2 0 4 .M) 2 
A. 1. 
u 2 - 
U ; (S0 4 .NH 4 ) 4 
U ; (C 2 0 4 .M) 4 
C 2 0 4 :[U:(C 2 0 4 .K) 3 ] 2 
B. 2. 
| 
S0 4 : U : (S0 4 .K) 2 
C 2 0 4 : U : (C 2 0 4 .M) 2 | 
* Bull. Soc. Chim., iii., 9, p. 590. 
t For particulars of the compounds included in this table, see Rosenheim 
and others, Zeit. filr anorg. Chem . , 20, p. 308, 26, p. 239, and 35, p. 424 ; 
Pechard, Compt. Rend., 116, p. 1513 ; and Kohlschutter and Rossi, Ber., 34, 
pp. 1472 and 3619. 
