CHAPTER II. Older Electrochemical Views.
The First Electrochemical Investigations.— The striking effects brought about by electricity formed the subject of much study about the middle of the eighteenth century. At that time friction electrical machines were in use, and in order to intensify the efiects produced, very large machines wei-e constructed. The most famous of these is still to be seen in the Teyler Museum in Haarlem. Pater Beccaria, some one hundred and thirty years ago, by using such machines found that metals could be " revivified " (i.e. reduced) fi-om their calces (oxides) when the electric spark was passed between two pieces. In this way he obtained zinc and mercury. Some time later, Priestley investigated the action of the electric spark on air and observed that an acid was produced ; he mistook this for carbonic acid, until Cavendish recognised it as nitric acid. Van Marum studied the behaviour of several other gases in the path of the electric spark [which led him to notice the formation of ozone], and made experi- ments also by passing the spark through liquids. Before him, Priestley had discovered that in oil and ether the electric spark produces gas, and proved that this gas contained hydrogen.
The first actual electrolysis was made by Deimann and Pacts van Troostwyk in Haarlem in 1789, in which they successfully decomposed water into hydix)gen and oxygen. In their experiments the water was contained in a cylindrical tube closed at the top, and having a metal wire sealed into its upper end. Another metal wire was introduced into the
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