502 M. Regnault on the Specific Heat of Simple Bodies, 



It will be seen from this Table that the rapidity diminished 

 regularly up to the third minute, as it ought to do according to 

 the law of Newton, for the quantity of heat lost is proportional 

 to the excess of the temperature of the body above the surround- 

 ing medium. From the third minute, the heat disengaged by 

 solidification commenced to disturb the law of cooling ; a remark- 

 able point is observed on the curve, which is disturbed in its 

 former course up to the thirteenth minute at which the observa- 

 tion is discontinued. Hence when the potassium had attained 

 the temperature of 35 degrees in its cooling after liquefaction, it 

 had even then not entirely disengaged its latent heat of fusion*. 



Lithium. 



It would be most interesting to know the specific heat of 

 lithium, for it could be decided thence whether lithium was to 

 be ranged among the alkaline metals with sodium and potassium, 

 or among the metals of the alkaline earths with barium and cal- 

 cium ; in other words, whether the formula of lithia ought to be 

 written Li^O or LiO. Bunsen has lately given a very convenient 

 method of preparing lithium by electrolysis. I tried this pro- 

 cess, and it succeeded admirably ; but it would have been difficult 

 to prepare with the chloride of lithium which I was able to pro- 

 cure, a quantity of metal necessary for an exact determination of 

 its calorific capacity. I preferred to operate at first on chloride 

 of lithium, with the intention of using afterwards the metal itself 

 if I could succeed in procuring it in sufficient quantity. 



The chloride of lithium was prepared from carbonate of lithia, 

 from the Exposition of M. Batka of Prague. The carbonate was 

 first washed with cold water, then dissolved in hydrochloric acid, 

 the solution evaporated to dryness, and then treated when cold 

 with strong alcohol. The substance dissolved almost entirely. 

 The filtered liquid was again evaporated, and the chloride of 

 lithium melted in a silver crucible. The liquid matter was 

 poured into a small brass mould, from which it was extracted on 

 cooling in the form of a cylinder pierced in the direction of its 

 axis. As chloride of lithium is at least as deliquescent as chlo- 

 ride of calcium, I folded it immediately in tinfoil and suspended 

 it in the oven for specific heats. The calorimetric experiment 



* I determined, by the same method, the stationary temperatures which 

 occur during the crystallization of sulphur and of iodine after their fusion. 

 In these two bodies the thermometer rests suddenly, and remains stationary 

 for several minutes. 



I found — 



For the temperature of the crystallization of sulphur... 1 13°"60 

 For the temperature of the crystalFization of iodine ... IIS^^'SS 



These two temperatures are obviously identical. 



