.360 
DR, MEYER WILDERMAN ON CHEMICAL DYNAMICS 
ebonite in the middle of the air space of the inner cylinder, so that the larger cone 
should be fully exposed to the light (except a little of the four corners, the whole 
cone was exposed) and the thermopile everywhere equally removed from the cylinder. 
To protect the thermopile from moisture, which is especially fatal to its iron wires, 
a cylinder with calcium chloride was put into the inner cylinder. By means of the 
tubes in front and behind, the copper cylinder was fixed in another larger copper 
cylinder, and the space between was filled with 6 or 7 litres of water. Except the 
small space of the larger tube in the front side, the narrow tube behind and 
two narrow tubes on the top, filled with Faraday wax, through which the insulated 
leads from the thermopile were drawn, the inner cylinder was thus enveloped on all 
sides by a thick layer of water. The outer copper cylinder was entirely covered by 
very thick sheets of asbestos. In this way any variation of temperature in the inner 
cylinder was counteracted by the conductivity of the copper sides, surrounded 
by water, while the thick sheets of asbestos and the large quantity of water between 
the cylinders made any rapid change of the temperature of the water due to 
alteration in the temperature of the room impossible. 
It was found that if a continuous water current from the main was passed between 
the two cylinders (even if the current was passed simultaneously in different places 
between the cylinders as well as between the front and back sides of the cylinder, 
and the water from the main was used only after half an hour or an hour, when the 
temperature of the water from the main ought to be constant), very large deflections 
of the g alvanometer, as much as several centimetres, were observed, and these varied 
continuously though the thermopile was closed to light and should have given no 
deflection at all. Obviously the temperature of the water from the main is never 
quite constant, continually varying by several thousandths or even hundredths of a 
degree Besides this, layers of different temperature may exist in the bulk of the 
surrounding water owing to the fact that the temperature of water from the main 
is lower than that- of the room, and that it must take a long time before the 
6 or 7 litres of water in the cylinders are replaced by fresh water from the main, 
i.e., the bulk of the water is exposed to the influence of the warmer temperature of 
the room for a longer time, and this warmer water is being continually mixed with 
the cold water from the main. This difliculty was finally overcome by leaving the 6 or 
7 litres in the cylinders to assume the temperature of the room, giving up the stirring 
altogether and replacing the same by the water current from the main. Through 
this the difference between the temperature of the water and that of the room was 
made very small, i.e., the warming of the water between the cylinders by the 
surrounding temperature of the room was made exceedingly slow. It should be 
observed that it is not the constancy of the temperature of the air space of the 
inner cylinder which we require, but that the variation of its temperature should be 
the same everywhere, and so slow that it should be in comparison with the velocity 
of cooling or warming of the thermopile by the surrounding air in the inner cylinder. 
