130 Crosse's Expei^knents with the Voltaic Battery. 



domestic purposes, and consisting mostly of silica. Two wires 

 of platina connected either end of the brick with the poles of a 

 Voltaic battery of sixty three pairs of plates, each about two 

 inches square. After many months' action, silica in a gelatinous 

 state formed in some quantity round the bottom of the brick, and 

 as the solution evaporated, I replaced it by fresh additions, so 

 that the outside of the glass basin, being constantly wet by re- 

 peated overflowings, was, of course, constantly electrified. On 

 this outside, as well as on the edge of the fluid within, I one day 

 perceived the well known whitish excrescence, with its project- 

 ing filaments. In the course of time, they increased in number, 

 and as they successively burst into life, the whole table on which 

 the apparatus stood, at last was covered Avith similar insects, 

 which hid themselves wherever they could find a shelter. Some 

 of them were of different sizes, there being a considerable differ- 

 ence in this respect between the larger and the smaller ; and they 

 were plainly perceptible to the naked eye, as they nimbly crawled 

 from one spot to another. I closely examined the table with a 

 lens, but could perceive no such excrescence as that which marks 

 their incipient state, on any part of it. While these effects were 

 taking place in my electrical room, similar formations, were 

 making their appearance in another room, distant from the for- 

 mer. I had here placed on a table three Voltaic batteries, uncon- 

 nected with each other. The first consisted of twenty pairs of 

 two inch plates, between the poles of which I placed a glass cyl- 

 inder, filled with a concentrated solution of silicate of potassa, 

 in which was suspended a piece of clay slate by two platina 

 wires connected with either pole of the battery. A piece of pa- 

 per was placed on the top of the cylinder, to keep out the dust. 

 After many months' action, gelatinous silica in various forms was 

 electrically attracted to the slate, which it coated in rather a sin- 

 gular manner, unnecessary here to describe. In the course of 

 time, I observed similar insects, in their incipient state, forming 

 around the edge of the fluid within the jar, which, when perfect, 

 crawled about the inner surface of the paper with great activity. 

 The second battery consisted of twenty pairs of cylinders, each 

 equal to a four inch plate. Between the poles of this, I interposed 

 a series of seven glass cylinders, filled with the following concen- 

 trated solutions : — 1. Nitrate of copper: 2. Sub-carbonate of po- 

 tassa : 3. Sulphate of copper : 4. Green sulphate of iron : 5. 



