646 Professor T. E. Thorpe [March 4, 



The rubber tube E connects the right limb of the glischrometer 

 with the glass tube 0, in which is inserted the three-way cock Z. In 

 the same way E' connects the left limb of the glischrometer with the 

 tube 0' fitted with the three-way cock Z'. At P, O and 0' are united 

 by a T piece which leads to the bottle M containing a quantity of 

 sulphuric acid, which can be abstracted or replaced by means of the 

 syphon W. The acid serves to dry air in its passage from the reser- 

 voir L to the glischrometer. When hygroscopic liquids are being 

 experimented upon, the exit tubes of the three-way cocks are provided 

 with small tubes filled with calcium chloride to prevent access of atmo- 

 spheric moisture to the glischrometer. In this way it is insured that 

 dry air only is in contact with the liquid under examination. 



By means of the tube N, which extends from within a few milli- 

 metres of the surface of the acid in M to a centimetre or so below 

 the cork L', and which is fitted with the cock Q, the air in M may be 

 put into communication with the large air reservoir L. This con- 

 sists of a glass bottle of about 30 lities capacity, encased in a wooden 

 box, and surrounded with sawdust to prevent excessive fluctuation 

 of temperature. A glass tube A', which reaches to within 5 milli- 

 metres, of the bottom of L, is connected, as shown, by india-rubber 

 tubing with the water reservoir E. The air in L is compressed by 

 raising the water reservoir, the height of which can be regulated by 

 a cord leading by a system of pulleys to the stud X, in close proximity 

 to the observer, and to the water manometer D D which indicates the 

 pressure set up in the confined air space. The manometer is con- 

 nected with the air reservoir by the tube I I, which has a common 

 termination with the tube N. 



After describing the method of making a viscosity observation, the 

 lecturer proceeded to indicate how the coefficients of viscosity for the 

 particular temperatures were deduced from the time and pressure of 

 iiow, and the constants of the glischrometer. 



The coefficient of viscosity rj may be found from the expression — • 



in which K is the radius of the capillary tube and I its length, and V 

 the volume of the liquid of density p passing through in time t and 

 under pressure p. The negative term of the formula gives the mea- 

 sure of the correction for the kinetic energy imparted to the liquid, 

 as deduced by Gouette and Finkener. 



With a view of tracing the influence of homology, substitution, 

 isomerism, molecular complexity, and, generally speaking, of changes 

 in the composition and constitution of chemical compounds upon 

 viscosity, a scheme of work was drawn up which involved the deter- 

 mination in absolute measure of the viscosity of between 80 and 90 

 liquids at all temperatures between 0° (except in cases where the 

 liquid solidified at that temperature) and their respective boiling 

 points. 



