POTASSIUM CYANIDE SOLUTIONS. 157 
ON THE DECOMPOSITION OF POTASSIUM 
CYANIDE SOLUTIONS BY MEANS OF PAR- 
TICLES OF GLASS. 
By Sypnrey Rabcuirr. 
In the following experiments, Potassium Cyanide, free from 
carbonate, and distilled water were used ; the glass particles 
were also cleaned by treatment with acid, ammonia, distilled 
water. “The method of experiment was as under :— 
An ordinary gauge glass tube was closed at one end with 
a piece of calico to form a filter; glass particles were filled 
in to form a column in the tube exactly 12 inches in height. 
The volume of the tube having been determined by weigh- 
img the amount of mercury required to fill it to the given 
height, and the specific gravity of the glass used being 
known, the volume of the void-space in the column of par- 
ticles was obtained. 
Particles of four degrees of fineness were experimented on. 
1. The particles passed through a 40 mesh sieve, remained on a 60 
2. ” ” ” 60 ) ” ” 80 
3- ” ” ” 80 7 ” 7 100 
4 ” ” ” 100 ” ” ” 120 
In each case 25cc. of solution, containing -2075gm. 
KCN were allowed to percolate through the column; this 
was immediately followed by a water-wash of equal volume. 
The total volume of solution passing through was measured, 
and the amount of KCN and KCNO in it determined. 
The particles were then removed from the tube, digested 
with dilute HCl, washed, and the amount of K in the filtrate 
estimated with platinic chloride. 
The cyanate formed was estimated by taking 10cc. of the 
solution, and adding AgNO, until all the AgCN and 
AgCNO was precipitated. The washed precipitate was 
treated with 5cc. normal HNO, and the acid remaining 
titrated with X NaOH. 
All experiments were made in duplicate. The results 
are given in the accompanying table :— 
Size of | Total | KCN |KON ox-\KCN re-|KCN un-| KCN [Retained 
particles. KCN Orl~| after per-|idised to/tained on! account-| to on 
Sieve. | Sinally | oolation.| KCNO. |particles.| ed for. | KCNO.|particles. 
present. 
grains. | grains. | grains.| grains. | grains. |per cnt.) per cent. 
40-60 *2075 “1880 *0169 "0026 | °00198| 7°7 1°25 
60-80 °2075 *1833 *0193 *0034 “00156 9-3 1°6 
80-100 *2075 *1720 *0305*| +0039 "0013 | 14°62} 1°87 
100-120 *2075 ‘1710 *0318 *0045 ‘0002 | 15°3 23M 
