. u. Pickering. Determination* to test [Dec. 11, 



for which the data are sufficient to calculate the values for C and c at 

 the fusing point are given there also ; these are, water, naphthalene, 

 using Alluard's values, and bromine. Regnault's determinations 

 of the heat capacity of ice at. low temperatures ('Ann. Chim. 

 Phys.' [3], vol. 26, p. 286) have been combined with Person's, 

 and give 0'4757 for ita value at ; this brings the temperature of 

 no crystallisation to 167, a value differing but little from Person's, 

 160. Regnault's determinations with bromine ('Ann. China. 

 Phys.' (3), vol 9, p. 344) give a result of doubtful value. He gives 

 the fusing point as 7'32, the heat of fusion as 16*185, and sufficient 

 data to calculate the heat capacity of the liquid as 0'1(05 + 0'00028f, 

 but for that of the solid his data are insufficient ; they may be taken as 

 indicating, though very doubtfully, 0-1038 + 0'00047/, a value which 

 gives C c negative ; or, if we take the mean of them, we get 0'0843 

 as the heat capacity at 48'96 C., a value which gives 992 for 

 the temperature of no crystallisation : as the heat capacity at the 

 temperature of fusion must be greater than at 48 '96, we may 

 safely say that a temperature lower than 992 is indicated as that 

 of no crystallisation. Some determinations with pentahydrated 

 sodium thiosnlphate were made by Trentimaglia (' Wien. Akad. Ber.,' 

 vol. 72, Abth. II, p. 669), with the express object of testing the 

 validity of Person's conclusion, but as the values for the heat capa- 

 cities were determined at one temperature only, and that not very 

 close to the melting point, I do not think that any conclusions can be 

 drawn from them. The probable error of my own results was calcu- 

 lated by taking half that which would be caused by taking such of the 

 extreme values for C, c, and I given in Tables I to X as would affect 

 the result in the same direction. 



Table C. 



Substance. t~ 



C-c 



Water -160 C. (Person, <tc. 



Monohydrate of sulphuric acid .... 177 + 2 (Pickering) 



Naphthalene -21450 



-333* (Alluard) 



Tetrahydrate of calcium nitrate 234 +9 (Pickering) 



Sulphuric acid 3694'/ 



Bromine > 992 (Regnault) 



These being the only results available for testing Person's view, that 

 the temperature of no crystallisation is 160 for all substances, we 

 must certainly conclude that this view has not yet been established. 



Taking the other ralue for c deducible from Alluard's results (0 3642), we get 

 -583. 



