310 Dr Wilson on the Electrical Magnetic Bell. 



temperature 35°, the volume of air obtained was 2-6 cubic 

 inches. The air so collected containing 31 per cent, of oxygen, 

 and in both cases freed from carbonic acid previous to 

 measurement. The proportion of oxygen increases slightly 

 as the temperature lowers. 



From the results given, it will be apparent, that a mass of 

 sea-water, cooling during a clear night of autumn or winter, 

 must be absorbing oxygen and nitrogen from the atmosphere, 

 and the more so when it is agitated. This action has often 

 appeared to me to be connected with the luminous-crested 

 waves, whichform so beautiful a phenomenon in rough weather. 



The temperatures are stated in the degrees of Fahrenheit's 

 scale. 



On the Applicability of the Electro-Magnetic Bell to the Trial 

 of Experiments on the Conduction of Sound, especially by 

 Gases. By George Wilson, M.D., F.R.S.E., F.R.S.S.A. 

 Communicated by the Royal Scottish Society of Arts.* 



The object of the following communication is to explain 

 to the Society an application of the Electro-Magnetic Bell to 

 the performance of experiments on the conduction of sound. 

 It is specially intended for ascertaining the conductivity for 

 sound of gases, and as a substitute for the present somewhat 

 inconvenient apparatus employed for that purpose. 



In experimenting on the transmission of sound by elastic 

 fluids, a bell-jar, emptied at the air-pump, and standing on 

 its plate, is filled with the gas about to be tested. A bell 

 contained within the jar is thereafter struck by a hammer, 

 set in motion by clockwork, which in its turn is made to 

 move by pushing a curved wire, passed air-tight through a 

 stuffing-box in the top, against a holdfast or ratchet, so as to 

 unlock the spring-barrel, and permit it to set the machinery 

 in motion. This clockwork is little within control of the 

 experimenter, and cannot be made to vary in its rate of 

 motion ; so that although it is quite sufficient for class illus- 

 tration, it is not convenient for the trial of varied experi- 

 ments, and it is expensive. The electro -magnetic bell has 

 all the advantages of the clockwork arrangement, is quite 

 under control, and is not costly. 



* Read before the Society, 2.3d February 1846. 



