IN NITRE BY THE AID OF ELECTRICITV. 
205 
The results may be thus arranged : — 
Exp. 1 lasted 4’’ in saturated solution of nitre, temp. 212° with 10 pairs. Half dissolved. 
Exp. 2 lasted 6’^ 5“, nitre, f water, average 109° with 5 pairs, 11 grs. dissolved. 
Exp. 3 lasted 6** lO*", nitre, f water, average 101° with 10 pairs, 14 grs. dissolved. 
Exp. 4 lasted 6*^ 20'", nitre, f water, average 100° with 10 pairs, 16 grs. dissolved. 
Exp. 5 lasted 6^ 45“, nitre, f water, average 106° with 10 pairs, 12 grs. dissolved. 
Exp. 6 lasted 3*^ 17“, i nitre, f water, average 98° with 20 pairs, 27^ grs. dissolved. 
So that uric acid calculi can be dissolved in a moderately dilute solution of nitrate 
of potassa at the temperature of the human body, by the aid of electricity, at the rate 
of from two to nine grains an hour. 
Section II. On the Solution of Oxalate of Lime Calculi. 
My original conjecture was, that sulphate of soda would prove the best solvent of 
oxalate of lime. Having however obtained so good an action on uric acid by a solu- 
tion of nitre, I determined first to see what the effect of the same solution would be 
on oxalate of lime. 
Experiment 1. — Half a small oxalate of lime calculus, weighing 42‘5 grains, was 
taken. The battery consisted of only five pair of Grove’s plates. 
The solution of nitre was of the specific gravity 1028. 
The action began at 9^ 25™a.m., the temperature of the solution then was 65°. 
The action was stopped at 4*' 35“ p.m., the temperature never rose above 90°. 
Total time 7^ 10“. 
The calculus was then removed and perfectly dried ; it then weighed 42 grains, so 
that in upwards of seven hours only half a grain was dissolved. 
Experiment 2. — The same calculus, weighing 42 grains, was again placed in the 
same solution. The strength of the battery was doubled, being ten pairs. 
The action began at 9** 35“a.m. and was continued to T' 15“ p.m., the temperature 
of the solution being between 70° and 115°. 
The action recommenced at 2^ 30“ p.m. and continued to 5^ 50“ p.m., the tempe- 
rature being between 75° and 104°. 
Total time 7^- 
For the last two hours there was a great diminution in the power of the battery. 
The calculus when dry weighed 40 grains, so that in seven hours only 2 grains had 
been dissolved. It appeared that the divided surface was the one attacked; to this 
the positive electrode had been applied. 
Experiment 3. — As the nitre solution had so little action, I proceeded to try the 
effect of a solution of sulphate of soda. 
A solution of sulphate of soda was made, having the specific gravity 1034. The 
battery was of the same strength as in the previous experiment, and the same calculus 
was used, so that the comparative action of the solution of nitre and the solution 
2 E 2 
