146 Messrs. A. Smithells, H. M. Dawson, and H. A. Wilson. 



9. Relation of Conductivity to Concentration of Solution sprayed and to the 

 Nature of the Salt. 



Results are given for solutions of the following substances : 



a. Potassium salts : Chloride, bromide, iodide, chlorate, nitrate, 



sulphate, carbonate, hydrate. 



b. Sodium salts : Fluoride, chloride, bromide, iodide, nitrate, sulph- 



ate, carbonate, hydrate. 



c. Lithium salts : Chloride, nitrate. 



d. Rubidium salts : Chloride, nitrate. 



e. Caesium salts : Chloride, nitrate. 



/. Hydrogen salts : Chloride, sulphate. 



The concentration of the solution varied from j-J-^th to J normal. 

 As an example of the range of work, it may be stated that potassium 

 iodide was investigated with i, -^5-, ^-, yj-^, ^^ normal solutions, in 

 each case measurements being made for E.M.F.'s of 5'6, 0'795, and 

 O2 27 volts. The set of measurements was repeated more than once r 

 as a rule, in order to avoid errors. 



The results show that at small concentrations equivalent solutions 

 of all salts of the same metal impart the same conducting power to the 

 flame. At higher concentrations this equality no longer holds good ; 

 the oxy-salts show a greater conducting power than the haloid salts , 

 the difference increasing with increasing E.M.F. 



Numbers proportional to the molecular conductivity are calculated 

 for the various salts, and it is shown (a) that in general the molecular 

 conductivity of a salt increases with increasing dilution ; (b) that the 

 oxy-salts of all alkali metals behave differently from the haloid salts ; 

 and (c) that at all concentrations investigated, the conducting power of 

 the oxy-salts of any one metal is the same. It also appears that with 

 increasing concentration the molecular conductivity of the oxy-salts 

 passes through a minimum value. 



In the case of the haloid salts the equation C = k ,Jq (where C is 

 the conducting power, q the concentration, and k a constant) holds 

 good to a certain extent, but this is not at all the case with the oxy- 

 salts. 



The conductivity increases with increasing atomic weight of the 

 metal, the increase being more rapid in the case of the oxy-salts than 

 in that of the haloids. 



10. Conductivity of Flames containing Acid*. 



The conductivity of acids in the flame is very small in comparison 

 with that of alkali salts. Ammonium salts being decomposed in the 

 flame, behave like their acid component. Sulphuric acid is doubtless 

 also decomposed in the flame. The conductivity of hydrochloric acid 



