IN NITRE BY THE AID OF ELECTRICITY. 
203 
The action began at 10’^ 10“a.m. and was continued to 1 p.m., the temperature of 
the solution being between 67° and 104°. 
The action was recommenced at 2^ 10“ p.m. and was continued to 5'^ 30“ p.m., the 
temperature being between 70° and 108°. 
Total time 6*^ 10“. 
The calculus was then removed, dried in a water-bath, after which it weighed 99 grs., 
so that in six hours about 14 grains of uric acid were dissolved. The external surface 
of the calculus which had been in contact with the negative electrode was corroded, 
whilst the internal surface, which consisted of oxalate of lime and which had been 
in contact with the positive electrode, was apparently very slightly acted on. The 
solution of nitre was much discoloured, and on evaporating, even a few drops, uric 
acid was immediately detectable. 
Experiment 4. — A whole uric acid calculus, weighing 111 grains, was put in a 
solution of nitre of specific gravity 1024-5. Ten pairs of plates were employed. 
The action began at 9^ 35“a.m. and was continued to 1^ 5“ p.m., the temperature 
of the solution being between 67° and 100°. 
The action recommenced at 2^ 10“ p.m. and was continued until 5 p.m., the tempe- 
rature being from 70° to 102°. 
Total time 6'’ 20“. 
The calculus when dried weighed 95 grains, so that in little more than six hours 
16 grains of uric acid were dissolved. The solution took place almost entirely at the 
negative or alkaline electrode. The solution of nitre became slightly alkaline. 
I was now desirous of trying whether the form of the electrodes at that part which 
was in contact with the calculus made any perceptible difference. Instead of a piece 
of thick platinum wire flattened, of the exact size and form of fig, 2, the wire was 
not flattened but only bent back. The breadth and length of the electrodes was 
nearly the same as in the previous experiments, but the surface in the former case 
was continuous, in the latter interrupted by a small space between the bent portions 
of the wire. 
Experiment 5. — A whole calculus, consisting chiefly of uric acid, with a thin 
external coating of oxalate of lime with a little phosphate of lime, was employed. It 
weighed 57 grains. At first the lower electrode was made positive, and the upper 
electrode negative. The power of the battery and the strength of the solution were 
the same as in the last experiment. 
The action began at 9^ 30“a.m. and was continued to 1 p.m., the temperature of 
the solution being between 64° and 1 10°. 
The action recommenced at 2 p.m., the electrodes were then reversed, the negative 
being below, and the action was continued to 5 p.m, ; the temperature was from 70° 
to 120°. 
Total time 6^ 45“, 
When dry the stone weighed 45 grains, so that the loss was 12 grains. Very little 
MDCCCLIII. 2 E 
