2 
Proceedings of the Royal Society of Edinburgh. [Sess. 
It is essential for the success of the method to employ a suitable form 
of manometer. The author has devised two forms of manometer, either 
of which may be employed with advantage, although the second is 
generally to be preferred. 
The first form, a sketch of which is shown in fig. 1, has been employed 
in a slightly modified form by C. G. Jackson * in the investigation of the 
cuprous-cupric bromide equilibrium. The manometer and the method of 
using it are fully described in Mr Jackson’s paper. 
Fig. 2 is a drawing of the second form of manometer.*|* A bulb a 
about 1 c.c. in capacity is blown on the end of a quartz tube b, 3 mm. in 
diameter, and flattened at one end so as to form a flexible quartz membrane 
c about T V mm. thick. This membrane is deformed by differences in 
pressure in the same manner as is the flexible metallic membrane of an 
ordinary aneroid barometer. 
The quartz plate d is in intimate contact with the membrane, and is 
so adjusted that a deformation of the membrane, caused by a difference 
in pressure between the outside and the inside of the bulb, causes d to 
* “ Owing to an unfortunate misunderstanding, this method was not clearly referred 
to in my paper {Trans. Chem. Soc., 1911, vol. xcix. p. 1066) as having been devised by 
Dr G. E. Gibson. — C. G. Jackson/’ 
t This is an improved form of a manometer which was described in the thesis presented 
by the author for the degree of Ph.D. at Breslau in July 1911. 
