38 Joty—On the Conservation of Mass. 
The thermometer was now inserted into the solution, when it fell to 9°°8. Hence 
the fall in the solution after about ten minutes was 1°1. 
From these experiments, it would appear that the air around the paper cylinder 
experiences a minute increase of density due to the first absorption of heat by the 
solution beginning probably during the fourth minute (or near the end of it) from 
the moment of contact. I may observe that I can detect nothing in the arrange- 
ment of the experiment to lead to the inference that a minute change of density 
of the air in contact with the paper vessel could lead to a horizontal force directed 
in any particular direction. Although we cannot suppose the cylinder to present 
perfectly perpendicular sides, what orientation to the vertical obtains must con- 
tinually vary with each fresh arrangement of the vessels within it and instalment 
of it in position. 
Experiments on the sensibility of the apparatus— Three experiments, using a 
magnet to accelerate the loaded beam. At the instant marked M, the magnet is 
applied (see fig. 1). The scale-readings before and after the force is applied show 
that an approximately steady state was attained at the moment of making the 
experiment, and that an acceleration resulted causing a rapidly increasing move- 
ment of the light-spot. The mean numerical value of the acceleration after the 
force has acted for thirty seconds is already given. It is derived as follows from 
the observations. 
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