TRANSACTIONS OF THE SECTIONS. 45 



nearly perfect hexagons are formed, and as the ch-cumference of each hexagonal 

 system is cooler than its centre, the floating particles are first arrested at the 

 circumferences, and gi-adiially accumulate there, giving an hexagonal appearance to 

 the sui-faee as the mass cools. In a crystalline material the tendency to assume its 

 peculiar crystal would prohably overcome these currents before the mass became 

 cool. 



The second part of the paper referred to the passage of an electric spark through 

 melted wax, &c. The early electricians remarked that a non-conductor, when melted, 

 became a conductor. Faraday foimd that when such substances were fused and 

 tested by their power to transmit a voltaic cun-eut, in no case did the cmTent pass, 

 unless accompanied by polarization of particles and decomposition. The same seems 

 to be true for fiictioual electricity. The substance to be tried was contained in a 

 glass bulb about 2 inches across in the widest part, and about 3^ inches hio-h, 

 fitted with corks through which pointed brass wires were passed, or one pointed 

 and one knobbed. On hanging such a bulb by its vnre to the prime conductor of 

 an electrical machine, connecting the lower wii-e with the earth, and setting the 

 machine in action, a most vivid spark plays between the -^-ires, strikino- out,°as it 

 were, from an anvil a midtitude of smaller sparks, and lighting up the whole of 

 the bulb and liquid in a remarkable manner. The smaller sparks, which apparently 

 fill the bulb, are globules of gas, ai-ising from the decomposition of a portion of the 

 liquid, and illuminated by the principal discharge. "When the point and bulb are 

 far apart, the dischai-ge is in the form of a brilliant rippled line of lioht, also accom- 

 panied by decomposirion"of the dielectric. The effects varv with diflerent sub- 

 stances, and also cliange with the cooling of each substance. Spermaceti, cocoa-nut 

 oil, lard, and solid paraffin are well adapted to these experiments, and also such 

 fluids as castor-oil, balsam of copaibs, paraffin oil, tui-pentine, and benzole. It was 

 not found possible to pass a spark through melted camphor. By holdiuo- a bulb 

 containing the solid over a spirit-lamp, the solid may be melted 'in a few minutes. 

 The phenomena form good class experiments. 



On a Phosphatic Deposit in the Lower Green Sand of BedfordsJiire. 



By J. F. Walkee. 



On a Projaoml Use of Fluorine in the Ilanufacture of Soda. 

 By "Walter "WELDOsr. 

 men sulphate of sodium is treated with hydrofluoric acid, one half of the 

 .sulphate IS converted into bisulphate and the other half is transformed into fluoride. 

 Upon this fact of the reaction between sulphate of sodium and hydrofluoric acid 

 yielding without any destruction of sulphuric acid, a compound almost as readily 

 caustifaable as carbonate of sodium itself, the author believed that it would prove 

 practicable to base a manufacturing process by means of which soda shoidd be pro- 

 duced, not only, if not exactly without the use, at any rate without any consump- 

 tion of sulphui-ic acid, but actually without the consumption of any materials 

 whatever excepting salt and coal, all the reagents employed beino- recovered for 

 use over and over agam continually. One method by which this obiect could be 

 accomplished was descnbed as foUows. It comprises four operation! the first of 

 which consists in the production of sulphate of socUum by double decomposition 

 between chloiide of sodium and sulphate of magnesium, havino- associated with it 

 at least one atom of water, the products of this reaction being, besides sulphate of 

 sodium, hych'ochloric acid and magnesia. The second operation consists in treating 

 two equivalents of sulphate of sodium with one equivalent of hydi-ofluoric acid" 

 whereby one equivalent of fluoride of sodium, which for the mhsi part precipi- 

 tates, and one equivalent of bisulphate of sodium, which remains in solution, are 

 tormed. Ihe thu-d operation consists in the decomposition of the fluoride of sodium 

 obtained in the second operation by means of the magnesia obtained as one of the 

 results of the first operation, the products being caustic soda and fluoride of mao-- 

 nesium; and the fourth operation consists in the decomposition of this fluoride of 

 magnesium by means either of the bisidphate of sodium obtained in the second 

 operation, or of its second equivalent of sulphuric acid, separated in any conve- 



