506 
any part of the world, however limited the space the light- 
house is necessarily required to occupy. The final conclusion of 
the C: mmittee on the relative merits of electricity, gas, and oil 
as lighthouse illuminants is given in the following words :— 
‘“‘That, for ordinary necessities of lighthouse illumination, 
mineral oil is the most suitable and economical illuminant, and 
that for salient headlands, important landfalls, and places where 
a very powerful light is required, electricity offers the greatest 
advantages.” ; 
In conclusion it may safely be asserted, now that the relative 
merits of electricity, gas, and oil have been accurately deter- 
mined, that these investigations of the Trinity House Committee 
will, for many years to come, furnish to the lighthouse authori- 
ties of all maritime nations of the world, and their engineers, 
very valuable data which cannot fail to assist very largely in the 
development of lighthouse illumination, and thus tend very 
matetially to present aids to navigation, and to a consequent 
reduction in the loss of life and property at sea. 
REPORTS 
Third Report of the Committee, consisting of Prof. Balfour 
Stewart (Secretary), Mr. $. Knox Laughton, Mr. G, F. 
Symons, Mr. BR. HH. Scott, and Mr. Fohnstone Stoney, 
appointed for the Purpose of co-oferating with Mr. E. F. Lowe 
in his Project of establishing on a Permanent and Scientific Basis 
a M.teo; ological Observatory near Chepstow.—In answer to a 
letter written by Prof. Balfour Stewart, pointing out certain 
conditions indispensable to the success of the project, Mr. 
Lowe writes :—‘‘ The (local) Committee think that they see 
their way to getting two or three thousand pounds if the 
scheme were started. Since you were with me I have pur- 
chased nearly 150 acres of land in front of the observatory, 
and nothing could come between it and the channel as near 
as 14 to 2 miles. A new road is to be made to the Severn 
Tunnel Station, and I hear that the telegraph or telephone is 
likely to be carried up this road. If your Committee think well 
to recommend the observatory scheme, action would be at once 
taken, and we have reason to believe that the Bristol Docks 
would help us with too/, a year. I should much like to see 
such an observatory in working order whilst I live, Lut my time 
is getting short. There is a growing interest round here about 
the observatory, and constant inquiries are made as to the proba- 
bilities of success.” The Committee express their sympathy 
with Mr. Lowe and his friends under the unfortunate circum- 
stances that have tended to retard local action. The Committee 
see such evidence of local interest in the undertaking that they 
desire to have an early opportunity of co-operating with the 
local Committee. They therefore ask for their re-appointment, 
and request that the unexpended sum of 25/. and an additional 
sum of the same amount—in all 50/.—be placed at their disposal 
for the purpo e. 
A Report of the Committee consisting of Frofs. Tilden and 
Ramsay and Dr. Nicol (Secretary), appointed fur the Purpose 
of Investigating the Subjet cf Vatour-Pressures and Refractive 
Indices of Salt Solutions, was read by Dr. Nicol. —The report deals 
with the general conclusions arrived at from recent experiments on 
vapour-pressures, rates of expansion, refractive indices, and 
saturation of salt solutions. The experiments on the vapour- 
pressure of salt solutions completely disprove the statement of 
Willner, that the diminution of vapour-pressure is directly 
proportional to the percentage of salt present ; in some cases 
it has been observed that the restraining effect of each molecule 
increased with the concentration, whilst with other salts it de- 
creased on the addition of salt even in dilute solutions. Such 
results can, however, be readily explained by the theory of solu- 
tion proposed by Nicol in the Philosophical Magazine, 1883. 
The Report of the Committe conststing of Profs. Ramsay, 
Tilden, W. L. Goodwin (Secretary) and D. H. Marshall, ap- 
pointed for the Purpose of Investigating Certain Physical Constants 
of Solutions, was read by Prv f. Ramsay.— his report contained 
an account of an investigation conducted by Profs, Goodwin 
and Marshall of the Queen’s Univerity, Kingston, Ontario, the 
object of which was the determination of the condition of equili- 
brium assumed by molecular weights of two salts placed in 
separate small vessels and inclosed with a weighed quantity of 
water. The process by which the water is so attracted to the 
alts was styled ‘‘ invaporation” by Graham, The salts experi- 
NATURE 
i 
ey) 
mented with were the chlorides of potassium, lithium, and 
sodium. When sodium and potassium chlorides were used, and 
different quantities of watei, it was found that sodium chloride 
invaporates the water more rapidly than potassium chloride, and 
that, with small relative quantities of water, the sodium chloride 
invaporates nearly all and leaves the potassium chloride almost 
dry. When this is compared with the state of equilibriun: 
assumed by equivalents of caustic soda, caustic potash, and 
sulphuric acid in solution together, it seems that the force in the 
first case is different in character from that acting in the second, 
Similar experiments made with sodium and lithium chlorides, 
and varying the relative quantities of water, showed that with 
small relative quantities of water the lithium chloride attracted 
the whole, but with larger quantities the sodium chloride attracts 
part, showing that in this case there is a limit to the quantity of 
water which the lithium chloride can hold against the attraction 
of sodium chloride. When the relative quantity of water is 
small, it is not divided between the two salts in the ratio of their 
attraction for water ; but this may be the case with large relative 
quantities of water. The process of invaporation is in all cases 
very slow, in some cases requiring several months for its com- 
pletion. A further investigation of these phenomena with 
other salts, and a study of the influence of temperature is 
promised. 
A Preliminary Report of the Committee consisting of Profs. 
McLeod and Ramsay, with Mr. W. A. Shenstone as Sccretary, 
appointed for the Further Investigation of the Influence of the 
Silent Discharge of Electricity on Oxygen and other Gases, was 
read by Mr. Shenstone.—A description was given of the appa- 
ratus devised for the storage and convenient manipulation of 
oxygen, so as to insure its perfect purity. The use of a mixture 
in molecular proportions of potassium and sodium chlorates is 
recommended in the preparation of oxygen, inasmuch as the 
breakage of apparatus, when potassium chlorate alone is used, 
is to a great extent done away with. 
The Report of the Committee consisting of Profs. W. A- 
Tilden and H, E. Armstrong, appointed for the Purpose of In- 
vestigating Isomeric Naphthalene Derivatives, of which Prof. 
H. E. Armstrong is the Secretary, was read by the latter, who 
pointed out that, owing to its constitution, naphthalene lends it- 
self very easily to the production of isomeric compounds. The 
constitution of the disulphonic acids of naphthalene has been 
specially investigated, and four isomeric compounds were 
described, as were also several isomeric bromo-derivatives. 
The Committee consisting of Prof. Sir H. E. Roscoe, Mr. 
Lockyer, Profs. Dewar, Liveing, Schuster, W. N. Hartley, ant 
Wolcott Gibbs, Capt. Abney, and Dr. Marshall Watts, appointe 
for the Purpose of Preparing a New Series of Wave-Lengt? 
“Tables of the Spectra of the Elements, of which Dr. Marshall 
Watts is the Secretary, reported that satisfactory progress had 
been made during the past year with the work allotted to it, and 
that the forthcoming volume of the Proceedings of the Associa- 
tion will contain additions to the tables of wave-lengths of the 
emission spectra of the elements and compounds. 
Report of a Committee, consisting of General F. T. Walker, 
General Sir F. H. Lefroy, Prof. Sir William Thomson, Mr. 
Francis Galton, Mr. Alex. Buchan, Mr. F. Y. Buchanan, 
Dr. Foln Murray, Mr. H. W. Bates, and Mr. E. G. 
Ravenstein (Secretary), appointed for the Purpose of taking 
into Consideration the Combination of the Ordnance and Ad- 
miralty Surveys, and the Production of a Bathy-hypsographicel 
Map of the British Isles.—(1) The Committee consider that 
the production of a plain outline map of the British Isles and 
surrounding seas, on a scale of 1: 200,000 (about three miles 
to the inch) would be desirable. Rivers, and such other physical 
features as can be shown in outline, to be marked distinctly. 
No hill-shading to be introduced. Roads, railways, towns, &e., 
to be indicated faintly, and merely for the purpose of identifying 
localities. Principal heights and depths above and below the 
datum level of the Ordnance Survey of Great Britain to be 
inserted. Contours to be drawn at intervals of 200 feet, with 
subsidiary contours where they are necessary, to give expression 
to the features of the ground. Incidental features, such as cliffs, 
&c., to be marked. ‘The map to be tinted according to height. 
(2) A grant of 25/. to be applied for in order that a specimen 
sheet of the map may be prepared. (3) The Clyde Trustees to 
be approached, with a view to their undertaking the prepara- 
tion of a similar map of the Clyde estuary on a suitably larger 
scale. Other harbour Boards to be similarly approached, 
[Sepz. 23, 1886 
~~ 
ot 
a 
