lOl Mr. E. D. Thomson's Mode of heating Water for a Bath. 



In cases where acids or acid sohitions alone are used, the 

 destruction of one or both surfaces, with the transfer of hydro- 

 gen or oxygen, seems to produce the same effect ; and the 

 inactivity of single circles or voltaic piles, in which pure water 

 is used, or saline solutions freed from air, seems to show that 

 the destruction of the surface of the oxidable metal is one of 

 the conditions of continued electrical action ; and the cessa- 

 tion of the power of De Luc's or Zamboni's piles, is always 

 connected with the tarnish of the imperfect metal employed in 

 them. 



Havino- published many years ago tables of the electro-che- 

 mical relations of metals, which have been copied into many 

 elementary books, I think it proper to give them here in a cor- 

 rected form with some additions, and the differences depen- 

 dent upon the nature of the menstruum. The metal men- 

 tioned first is positive to all those below it in the scale. 



With common acids. 

 Potassium and its amalgams; barium and its amalgams; 

 amalgam of zinc; zinc; amalgam of ammonium (?); cadmium, 

 tin, iron, bismuth, antimony (?), lead, copper, silver, palla- 

 dium, tellurium, gold, charcoal, platinum, iridium, rhodium. 



With alkaline soliitioiis. 

 The alkaline metals and their amalgams: zinc, tin, lead, 

 copper, iron, silver, palladium, gold, platinum, &c. 



With solutions of hydro-sulphurets. 

 Zinc, tin, copper, iron, bismuth, silver, platinum, palladium, 

 gold, charcoal. 



[To be continued.] 



XXIII. A Mode of Heating Water for a Bath. Bi/ Edward 

 Deas Thomson, Esq.* 



CONVINCED of the great utility of the warm bath to 

 health, as well as the comfort of it, I have for some time 

 turned my attention to the best and most oeconomical mode of 

 heating a bath ; and have endeavoured, as tar as possible, to 

 obviate the inconvenience, delay and expense, which are inse- 

 parable from the greater number of the methods hitherto in use. 

 The result has been to exceed my sanguine hopes ; having ob- 

 tained a bath containing 40 gallops of water at a temperature 

 of 98° Fahrenheit, in the space of half an hour from the time 

 of lighting the fire. The quantity of coals consumed was under 

 7 pounds, and the whole expense in London, including the 



* Communicated by the Author. 



faggot. 



