A6G4 REPORT——-1883, 
MONDAY, SEPTEMBER 24. 
The following Papers were read :— 
1. On Liquid Marsh Gas. By Professor Dewar, F.R.S. 
2. On Oritical Points and Pressures and their relation to Atomic Volumes. 
By Professor Dewar, F.R.S. 
3. On the relation between Chemical Constitution and Crystalline Form. 
By G. Jounsrone Stoney, F.R.S. 
4. Hlectrolysis of dilute Sulphuric Acid in Secondary Batteries. 
By Dr. J. H. Guavsrone, F.R.S., and ALFRED TRIBE. 
The authors in their recent papers had given the results of the chemical 
changes which take place in charging and in discharging secondary batteries of the 
Planté or Faure type. In expressing these changes by means of formule they 
had assumed that the compound decomposed in the cell was H,SO,. The present 
communication was to consider more fully the question as to what the compound 
electrolysed actually is. Is it water, as used to be supposed? Is it the actual 
H,80,? Or is it some chemical combination of the two, such as hexabasic 
sulphuric acid, which Frankland has lately assumed to be the electrolyte on the 
authority of Bourgoin’s experiments? The authors had tested the value of these 
experiments by means of a divided cell, in one limb of which was a solution of 
sulphate of copper, and in the other dilute sulphuric acid. They found that, 
independently of the actual molecular change, which in accordance with Grotthus’ 
hypothesis must ensue during electrolysis, there was also an actual passage of 
sulphuric acid into the limb containing sulphate of copper. The conclusion from 
this and other experiments was that we have no data to determine whether it is 
sulphuric acid or some hydrate that is electrolysed; but analogy would lead to 
the conclusion that it is sulphuric acid itself. Hence they retain the former simple 
method of representing the phenomena. 
5. On the Mobility of Gold and Silver in Molten Lead. 
By Professor W. Cuanpier Roszrts, P.B.S,. 
The author showed that metals interpenetrate when molten at very varying 
rates. Antimony and copper, for instance, alloy with comparative slowness, but 
on the other hand the mobility of silver and gold in lead and in bismuth is so rapid 
as to more nearly resemble the rate of diffusion of gases than that of a crystalline 
salt in a liquid, The methods of manipulation were given at length, and consist 
generally in observing the rate of passage of gold, starting with an alloy contain- 
ing 80 per cent. of the precious metal, through a curved or straight column of 
molten lead or bismuth. Exact numerical determinations have yet to be made, 
6. On Algin, a new substance obtained from Seaweed} 
By Epwarp C. C. Sranrorp, F.C.8. 
The author points out that a large fringe of marine vegetation surrounds the 
shores of Great Britain and Ireland, and that this constitutes an immense amount 
-of yaw material which is almost unutilised. The subject is discussed under three 
applications ; for food, for manure, and for the manufacture of kelp. There ought 
+o be a large application for food, as the plants are highly nitrogenous, resembling 
1 Published in extenso in the Journal of the Glasgow Philosophical Society, 1883 ; 
also in Chemical News, 1883, and Pharmaceutical Journal, 1883. 
