1 1 1 Royal Society : — 



terminal, the negative ball being surrounded with a narrow halo of 

 light similar to that in 6g. 1 A (p. 545), but smaller. In 190 there 

 was a red tinge on the cloud-like discharge near the positive terminal ; 

 on the approach of a magnet, two or three additional clouds were 

 brought out, the negative wire being covered with a luminous glow 

 extending to the sides of the tube parallel to the end of the negative 

 wire. 202 exhibited a remarkably well-defined cloud-like discharge, 

 the several clouds being clearly and distinctly separated. No. 219: 

 the appearance of the discharge in this tube was similar to that in 



Fig. 3 A. 



fig. 3 A, with a particularly brilliant glow around the negative ball, but 

 without any stratifications from the positive. 



Having thus described the appearances of the induced discharge in 

 these tubes, I now proceed to the description of experiments made 

 in the same vacua, — 1st, with the water-battery of 3520 cells ; 2ndly, 

 with the 5 1 2 series of Daniell's constant battery ; and lastly, with 400 

 series of Grove's nitric-acid battery. 



With the water-battery, as I have stated in my previous commu- 

 nication, the stratified discharge, similar in character to that of the 

 inductive coil, was obtained, not only in 146 and the other tubes, 

 but also through 146 and any one of the others at the same time. 



From the risk of fracture, I have not ventured again to heat the 

 potash in 146, but I have invariably found that whenever the potash 

 in any of the other tubes was heated, the discharge from the water- 

 battery, instead of increasing in distinctness and brilliancy, entirely 

 ceased. 



The discharge from the water-battery through each of the tubes 

 had the appearance of being continuous, and the needle of the 

 galvanometer, placed on the circuit, showed a steady deflection. 

 To test whether the discharge was continuous, I attached No. 219 to 

 my rotating apparatus (Philosophical Transactions, 1859, part 1. 

 p. 158); the discharges were then clearly separated, so that even 

 with this apparatus they were shown to be intermittent. 



As the water in the battery, after a lapse of some weeks, had 

 partially evaporated, the action was so reduced that it would no longer 

 pass through any of the vacuum-tubes except 219, in which it 

 assumed the appearance in fig. 3 B. In this state it remained for 

 three orfour weeks; and whenever from change of temperature moisture 

 was deposited on the surface of the glass tubes, the luminous discharge 

 disappeared when the tubes were touched by the hand or by a wire, 

 reappearing as the hand or wire was withdrawn. A portion of the 

 discharge from this battery was evidently lost by insufficient insulation, 

 reduced by accumulated dust and moisture. I have not the requisite 



