424 
MESSRS. T. B. THORPE AND J. W. RODGER ON THE RELATIONS 
actually observed is about 70 centims. In the case of ether, one of the most mobile 
of liquids, the critical velocity at 32°, as given by the above formula, is 360 centims., 
the actual value in the apparatus employed, even under the greatest head, is 
93 centims. It is evident, therefore, that our apparatus fails well within the 
requirements necessary for a stream without eddies. 
(2) On account of the high value for the velocity of efflux the kinetic energy 
correction (see p. 435) becomes in some cases comparatively large. Thus, in the 
extreme case of ether at 32°, under the highest pressure it is about 4 per cent. ; 
this is also the value of the correction in the case of water at 100°, although 
at 5° it is only T6 per cent. On the other hand, the recent investigations by 
Finkener, Couette, and Wilberforce have shown that the theoretical basis upon 
wdiich the evaluation of the correction depends is valid, and that the actual deter¬ 
mination of the numerical value can be made wdth a high degree of accuracy. In 
any case, the stoichiometric relations deduced from coefflcients of viscosity thus 
obtained will in all probability be unaffected by any modification of the theory 
relating to the correction. For this modification can at most lead to a correction on 
a correction, because it is obvious that the liquid does carry away kinetic energy, 
which must be allowed for. 
Moreover the legitimate use of the correction will give a means of testing its 
validity, as the final results thus obtained can be compared with those observations 
in which this correction is less important. Dearth of experimental data has been the 
main obstacle in deciding the worth of the correction, and if, as has been the custom, 
its effect 'were in all cases to be evaded instead of ascertained, the problem would 
never be brought nearer to solution. 
Determination of the Constants of the Glischrometer. 
Volumes of Liquid Passing through the Capillary Tuhe .—The volumes of liquid 
contained between the marks nd and nd on the left limb, and the marks nr" and iiV 
on the right limli, were obtained by gauging with water. Three w^eights were ascer¬ 
tained—(1) The weight of water filling the glischrometer up to the lower marks m~ 
and rV; (2) the weight of water filling the right limb up to the lower mark iiV, and 
tlie left limb up to the upper mark nd ; and (3) the weight of water filling the 
glischrometer up to the upper marks iid and nd. In determining any of these 
weights a quantity of freshly distilled water was introduced by means of the filling 
apparatus into the clean and dry glischrometer, which had been carefully weighed. 
The quantity of water introduced was adjusted until the levels of liquid in 
either limb nearly coincided with the desired marks, pains being taken not to wet 
the glischrometer above these marks. To obtain perfect coincidence between the 
liquid levels and the marks, the glischrometer was transferred to the water-bath, and 
by slightly altering the temperature and adjusting the quantity of liquid in either 
