406 
PROFESSOR 0. REYNOLDS AND MR. W. H. MOORBY 
Corrections to the Mean Value of K given hy the Experiments. 
I.—Length of Brake Lever. 
57. In dealing with the calibration of the measurements of the brake (par. 28), I 
have already mentioned that the value of K given by tbe experiments would require 
a correction factor of (1 -j- 0‘00042). 
IL—Salts Dissolved in the Manchester Water. 
58. Professor Dixon kindly furnished Professor Peynolds with the results of a 
number of analyses of the town’s water made during the College session, 1894-95. 
The dissolved salts were 
Common Salt, 14‘4 
Calcium Carbonate, 27‘7 
milligrammes per litre, 
therefore the proportion of salts by weight is 0*0000421, Taking their specific heat 
at 0‘2, we get for the correction factor required, due to the lowering of the specific 
heat of the water, 
1 + (1 ~ 0-2) X 0-0000421 = (1 + 0-00003). 
IIr.—Air Dissolved in the Water Used. —(Part I, par. 43.) 
59. Being rain water, it probably contained about 2|- per cent, by volume of dissolved 
air. As affecting the specific heat of the water, this air would not have of itself any 
sensible influence. 
It did, however, influence the resulting final temperature, as it was most probably 
all boiled out of the water, and the bubbles of expelled air would all be saturated 
with water vapour at a temperature of 212°, which vapour could not be formed 
without extracting its latent heat from the surrounding wmter. 
I made some experiments in December, 1896, with the object of determining the 
actual volume occupied by tbe bubbles of mixed air and water vapour under the 
conditions obtaining in the trials. The pressure on the water in the discharge-pipe 
was 10 inches of mercury veiy' nearly. 
The method adopted was as follows :— 
I put a depth of about two inches of mercury into the bottom of a strong bolt-head 
flask, and above the mercury I poured in 1^ lbs. of water. This filled the flask 
nearly to the brim. A rubber stopper, through which passed a glass tube, was then 
pressed into the neck of the flask, the glass tube being of such a length .that the 
insertion of the stopper displaced mercury only up the tube, care being taken that no 
bubbles of air ^vere included under the stopper. The stopper was then firmly tied 
into the neck, and the flask wats hung inside a large glass beaker, which was then 
filled with water to a depth which covered the top of the rubber stopper. 
