4i 6 Sir Humphry Davy on the relations of 
Some solution of nitrate of potassa was introduced into a 
glass basin of six inches in diameter, and large slips of paper, 
tinged with litmus and turmeric, were placed below the 
fluid, and connected with two pieces of foil of platinum ; so 
that the indications of the formation of acid and alkali, in 
any part of the basin, by electricity, would be instant and 
distinct. The two pieces of foil were now connected with 
the poles of a Voltaic battery : it was found that the alkali 
was developed only at the point or immediate surface of the 
negative platinum, and the acid in the same manner at the 
surface of the positive platinum ; and they then gradually 
diffused themselves through the fluid in a circle round the 
conductors, and there was no appearance of any repulsions 
or attractions of the menstrua in the line of the circuit. 
In various repetitions of this experiment the same result 
was obtained ; the alkaline and acid matters were influenced 
in their direction only by currents produced by the disen- 
gaged oxygen or hydrogen, or the inclination of the vessel ; 
in short, by mechanical causes only : and the same effects 
were produced on the test papers, as if a spherical piece of 
acid and an amalgam of potassium had been introduced in 
the places of the two poles. 
Mr. Herschel has shown, by some elaborate and ingeni- 
ous experiments in the last Bakerian Lecture, that an amal- 
gam of potassium, containing so minute a portion as some 
hundred thousand parts of its weight is strongly attracted so 
as to occasion violent mechanical motion, by the negative 
pole in a Voltaic arrangement : and if it be supposed that the 
fluid is divided into two zones, directly opposite in their 
