952 
Proceedings of Royal Society of Edinburgh. [sess. 
Note on the Boiling Points of Aqueous Solutions. By 
the Rev. S. M. Johnston, B.A. Communicated by 
Professor J. G. MacGregor, F.R.S. 
(MS. received July 17, 1905. Read same date.) 
In the course of a research on the boiling points of aqueous 
solutions, certain points came under my notice which have been 
introduced into this note. 
After considerable experience with various forms of Beckmann’s 
boiling point apparatus, and due consideration of the Jones type, 
a boiling point apparatus was designed which embraced what were 
considered the best points of each, in view of the research anti- 
cipated. The body of the tube was of the Jones type, and had 
a side tube fitted with a rubber stopper for the introduction of the 
salt at a short distance from the top of the tube. On the opposite 
side of the boiling tube, about the same height up, went off a 
condensing tube of the Beckmann pattern. The thermometer — one 
of Beckmann’s — read to hundredths of a degree, and, with the aid 
of a Beckmann reading glass, could be estimated to thousandths 
of a degree. It passed through a close-fitting rubber stopper at 
the top of the tube. 
In carrying out an experiment, garnets and platinum tetrahedra 
were used for filling material. The thermometer, when in position, 
was surrounded to a point above the surface of the solvent or 
solutions by a cylinder of platinum foil. Beneath the thermometer 
a few pieces of platinum foil were placed. The boiling tube was 
surrounded externally by a cylinder of glass of considerably 
larger diameter, and the space between was packed with asbestos 
wool. The heat was supplied by a gas jet, which was prevented 
from coming into contact with the boiling tube by wire gauze 
and asbestos paper. The whole apparatus was surrounded by a 
zinc cylinder in two portions, one of which could be removed at 
pleasure. 
With these precautions, a steady boiling temperature could be 
