of Edinburgh, Session 1884-85. 
149 
The three portions were all dried at 100°, and yielded on titrating 
the following percentages of oxygen : — 
A, .... 6-27. 
B, 7*2. 
C, . . . . . 5-6. 
The analysis of Zn, B gave the following results : — 
ZnO .... =77-1 
H 2 0 =13 
C0 2 = 4-1 
0 .... =7*2 
101-4 
Deducting carbonate of zinc represented by 4 - l per cent. C0 2 , 
and the water the percentage of 0 = 9-66. 
On heating B to 140° for ten hours it lost 9-36 per cent., and the 
residue on titration gave 5 per cent, of oxygen. This shows a loss 
of oxygen as well as water. 
In the preparation of the cadmium compound we used a solution 
of nitrate of cadmium containing 0*5 grm. to the cc. On the addi- 
tion of ammonia and then of H 2 0 2 solution, a precipitate is obtained 
which varies very considerably in colour according to the quantity 
of ammonia added. On adding 27 cc. of our ammonia solution to 
100 cc. of the cadmium solution, a buff-coloured precipitate is pro- 
duced by the H 2 0 2 solution ; but if a very little more or a very little 
less ammonia is added, the precipitate is much paler in colour, and 
approaches in appearance more nearly to the ordinary white hydrate 
of cadmium. 
Three portions, A, B, and C> were prepared as follows 
A. To 100 cc. of the cadmium solution 27 cc. of the ammoniacal 
solution were added, and then an equal bulk (127 cc.) of H 2 0 0 solu- 
tion, the precipitate filtered, and washed with cold water, 
B. The same quantities were used, but the liquid was filtered from 
the precipitated cadmium hydrate, and H 2 0 2 solution added to the 
filtrate. 
C. Was obtained by washing the precipitated hydrate from B 
with H 2 0 2 solution. 
