598 REPOET — 1886. 



apparatus for this operation is extremely simple, while the operation itself is rapid, 

 and avoids transference of the carbonaceous residue. Filtration is effected in a short 

 piece of combustion tubing, narrow at one end, and fitted with a filter of ignited 

 sand and asbestos. After drying, combustion is performed in the same tube by 



Filter and Combustion Tube. 



means of a very simple combiistion furnace, the cost of which is trifling, and which 

 stands on an ordinary working bench. The furnace has also been found useful for 

 a variety of other uses in the laboratory. 

 Sketches of the apparatus are annexed. 



WEDNESDAY, SEPTEMBER 8. 

 The following Reports and Papers were read : — 



1. Report of the Committee on Isomeric Naphthalene Derivatives, — 



See Reports, p. 216. 



Report of the Committee for preparing a netv series of Wave-length 

 Tables of the Spectra of the Elements. — See Reports, p. 167. 



3. On the Chemistry of Estuary Water. 

 By Hugh Robert Mill, D.Sc, F.B.8.E., F.C.S. 



Although chemical problems connected with ocean water and oceanic deposits 

 have been attacked by Forchhammer, Dittmar, and others, while recently Norwegian 

 and German investigators have done much to elucidate the conditions obtaining in 

 enclosed and partially enclosed seas, the chemistry of estuaiy water has been com- 

 paratively neglected. 



In investigating an estuary the first essential is to ascertain the salinity (ratio 

 of total dissolved matter to water), from point to point, and to trace its variations; 

 the second to perform accurate analyses of the saline and gaseous contents at various 

 positions suggested by the previous salinity observations. The first of these has 

 been done completely for the Firth of Forth, and partially for the Firth of Clyde 

 and some other river entrances in Scotland ; the second is in progress. By means 

 of the hydrometer (form used by Mr. Buchanan on the Challenger Expedition) the 

 distribution of salinity in the Firth of Forth has been proved to be nearly constant 

 aU the year round, while that of the Firth of Clyde is subject to periodical variations 

 through the whole mass of water. The conclusion drawn from the form of the 

 density (salinity) curve for the Forth river-entrance is that mixture of river and 

 sea water takes place by a true process of diffusion which produces and maintains 

 a constant (though not uniform) gradient of density from river to sea. Possibly 

 the difierent diffusive powers of the various potential compounds, the constituents 

 of which exist in solution, may determine the formation of certain salts, and lead to 

 the preponderance of these in certain places. The truth of this hypothesis will be 

 tested by the second part of the inquiry, which is now being commenced. 



Observations of alkalinity by the method of Tornoe showed a marked increase 

 of the (potential) calcium carbonate in solution with decrease of salinity, i.e., the 

 dissolved matter of fresher water was richer in calcium carbonate than that of sea- 

 water. 



