346 



MR. W. S. TUCKER ON HEATS OF 



Values of Q derived from these two equations are shown in the table (columns 3 

 and 4). THOMSEN'S results derived from the relation 



THOMSKN quotes results for concentration below HNO :i . 10H 2 0, but for them 

 neither of the above formulae holds. Referring to the simpler equation here adopted 

 good agreement is obtained except for N = 1 where an error of about 3 '5 per cent 

 is shown. 



The heat of dilution at any given concentration is now given by 



dQ 2020 



dN '" N 



i.e., with slight error the heat of dilution is proportional to the concentration. 

 (Diagram II.) 



Developing a similar argument to that employed for sulphuric acid, there will be 

 no limiting hydrate formed. 



(3) Hydroibromic Acid. 



THOMSEN gives six values for total heat of dilution for various concentrations 

 of hydrobromic acid. The last of the series is for a weak solution, and is ignored. 

 The equation is derived from the concentrations N = 3 and N = 6, is 



Q = 3356 log e N + 12,222. 



