TRANSACTIONS OF THE SECTIONS. 15 



Out of a great number of specimens of different kinds of insulators, he found that 

 gutta percha, with the exception of Chatterton's compound, absorbed less water 

 under a pressure of 20,000 lbs. on the square inch than any of the others, and that 

 it closed much tighter upon the conducting wires than any of the other materials 

 experimented upon. 



As regards the ' Great Eastern' ship and the paying-out machinery, he went in her 

 from the Nore to Yalentia for the purpose of witnessing the behaviour of that vessel, 

 and nothing could be more satisfactory than the ' Great Eastern ' as a submerger. 

 Her smooth and easy motion at sea, and the efficiency of the paying-out machinery, 

 were in every respect calculated to ensure success; and it was much to be resetted 

 that this important enterprise had failed from causes over which the parties engaged 

 had probably no control. 



On the Change of Form and Colour which the Stratified Discharge assumes 

 when a Varied Resistance is introduced in the Circuit of an Extended Series 

 of the Voltaic Battery. By J. P. Gassiot, V.P.R.S. 



Some months since the author commenced the construction of a voltaic battery, 

 consisting of 4000 insidated glass cells, into each of which, in lieu of sulphate of 

 copper, as used by the late Prof. Daniell, about a tablespoouful of sulphate of 

 mercury is introduced ; the elements carbon and amalgamated zinc plates are then 

 inserted, and the cells filled with rain-water. In this form of battery the zinc 

 plates apparently remain free from local action, and are consequently not oxidized 

 or acted upon, except when the circuit is completed. When the, battery is in action, 

 sulphate of zinc is obtained in solution, and the mercury that is set free assists in 

 the amalgamation of the zinc plates : the water being so slightly acidulated, and 

 the resistance in the carbon plates being so much greater than if this element of 

 the battery had been a metal, the amount of chemical action, and that of the elec- 

 trical force, is proportionally less than that in the nitric-acid battery ; but the dis- 

 charge is constant and regular in a most remarkable degTee. For his researches 

 upon electric stratified discharges the author has now more than, four hundred 

 vacuum-tubes, some exhausted by himself, and others by Geissler, of Bonn. In 

 one of the latter he obtained certain phenomena which it was the more immediate 

 object of this communication to describe. The appearances in the tube, with 

 discharges from 1200 and 4000 series of the battery taking place, and when the 

 resistance of various lengths of a column of distilled water is introduced into the 

 circuit, were illustrated by diagrams. The water is contained in a tube half an 

 inch in diameter, and three feet long ; two wires are introduced into it, one being 

 connected with one terminal of the battery, and the other with the vacuum-tube ; 

 while by raising or lowering either of the wires the length of the column of water 

 remaining in the current is increased or diminished, and in this way the amount of 

 resistance can be altered with great facility. When one wire is inserted in the 

 water, and the other touches the moistened surface of the glass, but is not in actual 

 contact with the water, a luminous discharge will be observed, filling the entire 

 tube, without any sign or appearance of stratification. On depressing the wire, and 

 thus bringing it into contact with the surface of the water, small crescent-shaped 

 disks of red light are observed to be rapidly produced in quick succession from the 

 positive pole. On shortening the resistance by farther depression of the wire, the 

 disks commence receding, one by one disappearing at the positive terminal, until 

 nineteen remain, much increased in brilliancy and definition. From this condition 

 of the discharge a remarkable change takes place on further depressing the wire and 

 reducing the resistance ; the two disks nearest the negative terminal join together, 

 assuming the form of a double-convex lens, the side facing the negative being of a 

 slightly blue tinge, that towards the positive of a reddish fawn, and the centre a bril- 

 liant red colour. At the instant this change of form and colour takes place in the two 

 disk's, another crescent-shaped disk sinmlfaneously appears at the positive terminal ; 

 and as the depression of the wire in the water is continued, each of the two disks 

 nearest the negative terminal will successively join, and assume the double-convex 

 form described, at every such change another crescent-shaped disk simultaneously 

 appearing. When the circuit is completed without any resistance of water being 



