TRANSACTIONS OF SECTION A. 557 



On forme toutes les valeurs de et , p^ p^ et ju'\ etant successivement les 



■divers diviseurs de n ranges par ordre de grandeur, jusqu'ii ce que deux de ces 

 valeurs comprenneut entre elles le rapport =f de la resistance d'un element a la 

 resistance du circuit exterieur: le uombre p' sera celui qu'il conviendra de prendre. 



13. On an Easy Method of makinq Carbon Cells for Galvanic Batteries. 



By W. Symons, F.G.S. 



At tlie Belfast meeting of the Association the author described a method of 

 making carbon cells by repeatedly dipping paper moulds in a mixture of syrup and 

 line carbon. This is a practicable but tedious process. A much easier and more 

 expeditious method is the following : — Mix together 15 parts of powdered gas 

 cai-bon, 3 parts of v^ood charcoal, and 10 parts of lump sugar. Well shake down 

 this powder, dry into paper moulds of the size and shape required, cylindrical 

 being the most manageable. Bury the iilled moulds in sand in a suitable iron or 

 copper vessel, and gradually expose to a red heat. When cold remove the burnt 

 paper from the now solid cells, and soak them in a syrup made of equal parts of 

 lump sugar and water. Well dry the cells, wrap them up in paper, again bury in 

 sand, and gi'adually expose them for some time to as strong a heat as practicable, 

 but not less than a bright red heat. For this purpose the author has used an 

 extempore furnace made of Fletcher's solid-flame burner, surmounted with a com- 

 mon unglazed earthenware drain-pipe, partially closed with an iron dome. This 

 furnace is easily constructed, and is useful for a variety of purposes. The draught may 

 -of course be increased hj adding a pipe to the iron dome. In the author's expe- 

 rience a carbon mixture of the above proportions is the best. Cells made with 

 other kinds of carbon crack more or less, but the above mixture, with due care, does 

 not crack. 



I 



14. On an Antimonized Cellular Garhon Galvanic Battery. 

 By W. Symons, F.G.S. 



Faraday, in his ' Experimental Researches,' p. 2012, 'On the Order of the Metallic 

 Elements of Voltaic Circles,' places antimony highest of the metals tested by him 

 -with hydrochloric acid. This fact suggested to the author the construction of a bat- 

 tery made with carbon cells as described in the previous paper, with antimony 

 precipitated on the carbon, using zinc rods unamalgamated and a solution of 

 ammonium chloride, but, with very limited leisure, he has not been able to complete 

 an efficient battery in time for this meeting. He, however, ventures to suggest 

 such a battery as a useful one for general laboratory purposes, being somewhat 

 .similar to Smee's in action, but with much cheaper negative elements, and a more 

 economical utilization of the zinc. By boring holes also in the carbons, he believes 

 that polarisation will be diminished, by thus increasing the amount of efficient 

 •carbon surface and promoting the circulation of the liqidd, but at present he has 

 not had time to test this point. The carbon cells can be made small enough to be 

 nearly close to the zinc, while, by having the containing vessels of an ample size, 

 the constancy of the current will be enhanced. Another form of the battery 

 which he proposes to make is with larger carbons and porous diaphragms, using 

 for the outer liquid a mixture of antimonious chloride and ammonium cliloride. 



Perhaps it may not be amiss to add that plaster of Paris diaphragms can also 

 be easily made with dry plaster. Provide an inner core or mould of turned wood, 

 a little taper and with a shoulder the required thickness of the diaphragm ; round 

 this tie two thicknesses of stout blotting-paper, well shake down the dry plaster 

 •between the wooden core and the paper. Then immerse the whole in water. In a 

 few minutes the diaphragm will be solid and can be removed from the mould. 



