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VIII. On a simple Electro-chemical Method of Ascertaining the Presence of 
different Metals ; applied to detect minute quantities of Metallic Poisons. By 
Edmund Davy, F.R.S. M.R.I.A. 8$c. Professor to the Royal Dublin Society. 
Read November 25, 1830. 
1. Introduction. 
It is now nearly a quarter of a century since the late Sir Humphry Davy, by 
a train of masterly researches, developed the general principles of electro- 
chemical action, which subsequently led him to many fine discoveries and 
important practical applications. Some years since, I repeated most of the 
interesting experiments noticed in his excellent Bakerian Lecture “ On the 
chemical agencies of Electricity*.” On the decomposition of metallic salts by 
the Voltaic battery, Sir Humphry is very brief. He clearly ascertained, how- 
ever, that “ when metallic solutions were placed in the circuit, metallic crystals 
or depositions were formed on the negative surface ^ and that “ the metals 
passed towards the negative surface, like the alkalies, and collected round it -j~.” 
In the course of my experiments on this subject, phenomena occurred which 
led me to think that some novel results might be obtained by instituting a 
series of experiments on metallic salts, using as a Voltaic arrangement the 
feeble power produced by the contact of small slips of different metals, with 
solutions of the common metallic salts. Operating in this manner, I could 
readily detect very minute quantities of different metals, coat platina with 
gold, silver, copper, &c., or cover gold with a surface of these metals, and tin, 
copper, brass, iron, &c. Several of those facts I have been in the habit of 
bringing forward and illustrating in my annual courses of lectures delivered 
both in the Royal Cork Institution, and in the Royal Dublin Society. Circum- 
stances which it is unnecessary to mention, have hitherto prevented me from 
* * Philosophical Transactions of the Royal Society, 1807. 
u 2 
T Ibid. 
