TRANSACTIONS OF THE SECTIONS. 47 
disturbance in the parallel or secondary conductor (such disturbance being in the 
nature of a magnetic affection), and that such disturbance correlatively induces the se- 
condary current, both when it is produced and when it ceases. This hypothesis is 
also in accordance with the fact that this induced current is only transient, and also 
appears the best explanation why the induced is not of equal duration with the 
indueing current. 


On the comparative Cost of working various Voltaic Arrangements. 
By W. Syxes Warp. 
The author stated that a series of calculations, founded on tables produced to the 
Chemical Section at Swansea, showed the efficient power of three generally used 
forms of battery, known as Smee’s, Daniell’s and Grove’s, would be equal when 100 
pairs of Smee’s, 55 pairs of Daniell’s, or 34 pairs of Grove’s were used ; and that the 
expense of working such batteries, as regards a standard of 60 grains of zinc in each 
cell per hour, would be about 6d., 7id. and 8d. respectively. 
On the Presence of Nitrogen in Mineral Waters. By W. West, F.R.S. 
In this paper the author corrects the statement of Dr. Granville, in his ‘Spas of 
England,’ that the continental chemists do not find nitrogen gas in their analyses 
of mineral waters ; whence the Doctor infers either some extraordinary difference be- 
tween the spas of England and of the Continent, or some error in the experiments of 
British chemists. Mr. West showed, by quotations from many statements, prin- 
cipally of German chemists, that they at least, in many instances, state the propor- 
tion of nitrogen found by them, and that in those cases where this is omitted, the 
absence of nitrogen is not to beinferred, but only that they made no examination of 
the gaseous contents, beyond ascertaining the quantity of carbonic acid present. 
On the Presence of Fluorine in the Waters of the Firth of Forth, the Firth of 
Clyde, and the German Ocean. By Grorce Wixson, M.D., F.R.S.E. 
In 1846, the author announced to the Royal Society of Edinburgh the discovery 
of fluorine as a new element of sea water. He was led to search for it, after ob- 
serving that fluoride of calcium possesses a certain small but marked solubility in 
water, which explains its occurrence in springs and rivers, and necessitates its occa- 
| Sional, if not constant presence in the sea. The only specimens of sea water he had 
| €xamined before this summer were taken from the Firth of Forth at Joppa, about 
_ three miles from Edinburgh. He obtained the mother-liquor, or bittern, from the 
_ pans of a salt-work there, and precipitated it by nitrate of baryta. The precipitate, 
after being washed and dried, was warmed with oil of vitriol in a lead basin, covered 
with waxed glass having designs on it. The latter were etched in two hours as 
deeply as they could have been by fluor-spar treated in the same way, the lines being 
filled up with the white silica separated from the glass, 
The author has recently examined in the same way bittern from the salt-works at 
Saltcoats in the Firth of Clyde, but the indications of fluorine were much less di- 
stinct than in the waters on the east coast. On procuring, however, from the same 
place, the hard crust which collects at the bottom and sides of the boilers used in 
the evaporation of sea water, lie found no difficulty in detecting fluorine in the deposit. 
_ This crust, or deposit, consists in greater part of sulphate of lime and of carbonate of 
lime and of magnesia ; but it contains also much chloride of sodium, and the other 
soluble salts of sea water entangled in its substance. When sulphuric acid, ac- 
_ cordingly, is poured on it, it gives off much hydrcchloric and carbonic, as well 
as some hydrofluoric acid, and the latter is thus swept away before it has time to 
_ corrode the glass deeply. The author preferred, nevertheless, to use the crust 
_ exactly as he got it, that the proof of the presence of fluorine might not be impaired 
in validity by the possibility of that substance being introduced by the water or re- 
agents which must have been employed, had the chlorides and carbonates been sepa- 
_ vated from the crust by a preliminary process. The crust, accordingly, after being 
_ dried and powdered, was placed along with oil of vitriol in a lead basin covered by 
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