46 REPORT— 1855. 



earth, might be carried up into the interior of the revolving mass to an extent suffi- 

 cient to account for all the appearances which have in any case been actually 

 observed. Formulae were shown giving the necessary velocity in any supposed case. 

 An experimental apparatus was next exhibited, whereby the appearances of the 

 waterspout can be easily and completely produced on a small scale. A rectangular 

 box, about 18 inches square, formed of plates of glass, placed merely edge to edge 

 at the corners, but not cemented, is covered by a plate of glass with a hole about 

 If inch in diameter in the centre of it. This box is suspended to the roof by 

 means of a twisted string, and the interior filled with the smoke rising from burning 

 nitrated paper. A film of loose cotton wool is placed on the opening in the lid, 

 and the box set into rotation. In a short time the air enters at the opening as the 

 smoke is pressed out by the centrifugal action at the edges of the plates, and a tube 

 exactly resembling the waterspout descends in the interior. It frequently divides 

 into two, three, or more tubes which coil round each other ; and as their shreds, 

 often of a flat or spiral form, turn themselves in different positions to the eye, the 

 appearance formerly referred to, of a drinking action, is exhibited. Small holes 

 pierced in the bottom, allowing air also there to enter, give rise to the formation of 

 an ascending column which meets and joins with the descending one, precisely as 

 on the great scale in nature. 



CHEMISTRY. 



On the Polar Decomposition of Water by Common and Atmosjjheric 

 Electricity/. By Thomas Andrews, M.D., F.R.S., M.R.I.A. 



In the fine experiment first made by two Dutch chemists, and afterwards modified 

 and extended by Wollaston, water was decomposed by a succession of disruptive dis- 

 charges produced by the common electrical machine. But in this experiment, as 

 Wollaston himself has correctly remarked, we have only an imitation of the galvanic 

 phsenomena, and the essential differences between its results and true electro-chemical 

 decomposition have been pointed out by Faraday with his usual clearness and ability. 

 " The law which regulates the transference and final place of the evolved bodies," the 

 latter remarks, " has no influence here. The water is evolved at both poles, and the 

 oxygen evolved at the wires are the elements of the water existing before in those 

 places." 



The same distinguished experimentalist obtained only uncertain results when he 

 attempted to procure the true polar decomposition of water by common electricity, 

 that is, to decompose it so that the oxygen might be evolved at one pole and the 

 hydrogen at the other. " When what I consider the true effect only was obtained," 

 he says, " the quantity of gas given off was so small that I could not ascertain whe- 

 ther it was, as it oughl to be, oxygen at one wire and hydrogen at the other. Of the 

 two streams, one seemed more copious than the other ; and on turning the apparatus 

 round, still the same side in relation to the machine gave the largest stream. But 

 the quantities were so small, that on working the machine for half an hour, I could 

 not obtain at either pole a bubble of gas larger than a grain of sand." 



On repeating this experiment with wires of different lengths and thicknesses, I 

 obtained the same uncertain results, although I had at my command a stream of 

 electricity of great power, and which could be maintained without intermission for 

 many hours. But while engaged in some experiments on the conversion of oxygen, 

 contained in fine thermometer tubes, into ozone, the tubes being inverted in water, I 

 found to my surprise that the gas in certain cases steadily augmented in volume, and 

 on further inquiry I found that the augmentation of volume arose from the water 

 Laving imdergone polar decomposition. The conditions under which the gases arising 

 from the polar decomposition of water might be obtained were now quite manifest, as 

 •was also the cause of no appreciable amount of gas having been obtained in former 

 investigations. The quantity of gas produced in fact in a given time from the elec- 

 trolysis of water, by means even of a powerful electrical machine, is so small, that the 



