2 6 
Mr. Davy’s Lecture on some 
When solution of sulphate of potash was in the negative 
part of the circuit, distilled water in the positive; part, and 
saturated solution of barytes in the middle, no sensible quan- 
tity of sulphuric acid existed in the distilled water after 30 
hours, the power of 150 being used ; after four days, sul- 
phuric acid appeared, but the quantity was extremely minute ; 
much sulphate of barytes had formed in the intermediate 
vessel ; the solution of barytes was so weak as barely to tinge 
litmus ; and a thick film of carbonate of barytes had formed 
on the surface of the fluid. With solution of strontites the 
result was very analogous, but the sulphuric acid was sensible 
•in three days. 
When solution of muriate of barytes was made positive by 
the power of 150, concentrated sulphuric acid intermediate, 
and distilled water negative. No barytes appeared in the dis- 
tilled water, when the experiment had been carried on for 
four days ; but much oxymuriatic acid had formed in the 
positive vessel, and much sulphate of barytes had been de- 
posited in the sulphuric acid. 
Such of the metallic oxides as were made subjects of expe- 
riment passed through acid solutions from the positive to the 
negative side, but the effect was much longer in taking place 
than in the instances of the transition of alkaline matter. 
When solution of green sulphate of iron was made positive, 
solution of muriatic acid intermediate, and water negative, in 
the usual arrangement, green oxide of iron began to appear in 
about ten hours upon the negative connecting amianthus, and 
in three days a considerable portion had been deposited in the 
tube. Analogous results were obtained with sulphate of 
copper, nitrate of lead, and nitromuriate of tin. 
