9 
~_ 
16 REPORT—1896. 
duct was again dissolved in nitrie acid, and was fractionally precipitated 
by ammonia, the first and last fractions being rejected. The middle 
fraction, after thorough washing, was preserved and used in the prepara- 
tion of the final test solutions of bismuth. 
The first solution of bismuth nitrate prepared contained, in 25 c.c., 
0-125 grme. of bismuth. This contained a sutticient excess of nitric acid 
to prevent precipitation unless diluted with about ten volumes of water. 
In the following series of estimations 25 c.c. of the solution were used 
in each case, and either diluted to 150 c.c. in a platinum dish with water 
only, or made up to the total volume of 150 c.c. with water after addition 
of the various substances stated below. The electrolysis was then com- 
menced with the current specified, and the action usually allowed to 
continue all night. At the end the current was generally increased, in 
order to complete the deposition. 
As slight oxidation takes place at the edge of the liquid even with 
apparently very good reguline deposits, the latter, when washed, dried, 
and weighed, were in some cases oxidised by nitric acid, the solution 
carefully evaporated to dryness, and heated until the bismuth nitrate was 
converted wholly into Bi,O,. From the oxide obtained the weight of Bi 
was then calculated. This operation is easily executed in the electrolytic 
dish, and was found to be a useful check, especially when the results of 
electrolysis seemed too good. 
| Bi from | 
A 24 F F Bi 
0 phen solution | Currents in as Metal! Bi,0; | Remarks 
iluted to 150 c.c. Amperes grme. weme. ) 
1. Water and Nitrate 0-008 0-13 — | Loose deposit, evident 
only increased | | oxidation. 
at end to | | 
0:05 
2. Ditto ‘ é 0:05 0:1238 — | Loose, but reguline. | 
3. +2 ¢c.c. strong Me- 0:02 0-124 — | Very firm deposit, easily 
taphosphoric acid washed. No apparent 
solution | oxidation. 
4. +2c.c. HPO, solu- | OOSin- | 0127 | — _ | Notso firm, and not per- 
tion creased to fectly reguline. 
0:05 at end 
5. +4¢.c. HPO, solu- 0:03 to 07125 01248 | Very firm and reguline ; 
tion 0:05 at end | | easily washed. 
6. +1 grme. of Citric | 0:008 to | 0:130 01238 | Firm,but coloured owing 
Acid 0-01 | | to oxidation. 
7. +1 grme. of Citric 0-01 to 0:05} 0126 | — Firm good deposit ; 
Acid | slightly oxidised. 
8. +2 grmes. of Citric 0-01 01246 | — Very firm, easily washed, 
Acid | and apparently unoxi- 
dised, 
9. +2 grmes. of Citric 0:01 01246 | 0:1246 | :, # 
Acid 
10. +25 grmes. of |0:01 to01} 0125 0°1249 of ”» 
Citric Acid at end 
11. +25 grmes. of |0-01 to0-1| 0125 | 0-1247 | ‘ 7 
Citric Acid at end | 
12. 0°05192 grme. of Bi | 0-005 to | 0:0526 | 0:052 | 1H 7 
as Nitrate + 2°75 |0-Olat end | 
grme. Citric Acid | 
13. 0:07 grme. of Bi as | 0:005 to | 0:07 0:0697 | A » 
Nitrate + 2:2erme. |0:01 at end | 
of Citric Acid 
