﻿148 M. C. Marignac on the Specific Heats, Densities, 



p denoting the weight of the salt dissolved in 100 parts of water, 

 and 0*214 the specific heat of chloride of sodium in the solid state. 

 This formula is evidently inaccurate for very dilute solutions, 

 since the conclusion from it would be that the specific heat of 

 those solutions could not exceed 0*9624, however minute might 

 be the proportion of the salt. Prom this formula, the following 

 would be the specific heats of the solutions examined by me : — 

 n. p. Calculated. Observed. 



12-5 26 0-8063 0-8100 



25 13 0-8754 08761 



50 6-5 0-9162 0-9282 



100 3-25 0-9386 0-9592 



200 1-62 0-9503 0*9785 



With respect to solutions containing more than 25 molecules 

 of water the disagreement is absolute. 



Sugar: C^H^'+Aq*. 



p. C. C-18«. 



792 598-6 148*6 



1242 1046 146 



2142 1947 147 



3942 3745 145 



7542 7347 147 



Within the limits of errors of experiment, the numbers in the 

 last column may be regarded as equal. The conclusion hence 

 is, that the specific heat of a mixture of water and a solution of 

 sugar is always sensibly equal to the sum of those of the two 

 liquids mixed. 



It may therefore be admitted that the specific heat of any so- 

 lution of sugar is the sum of those of the water and the sugar, 

 that the mean number 147 expresses the molecular heat of sugar 

 in the liquid state, and that its specific heat per unit of weight 

 is consequently 0*430. 



According to M. H. Kopp, the specific heat of sugar in the 

 solid state is 0*301, its molecular heat 103. The ratio of these 

 numbers to those belonging to the liquid state offers nothing 

 abnormal. 



Solutions in Sulphide of Carbon. 



As mentioned at the commencement of this memoir, all the 

 experiments on these solutions were compared with those made 



* Theoretical considerations, to which I shall return at the close of this 

 memoir, made me desirous of studying solutions not belonging to the group 

 of salts, acids, and bases. In consequence of the difficulty of finding such 

 bodies presenting in addition the conditions of great solubility, perfectly 

 definite composition, and not combining with water, the aqueous solution 

 of sugar is the only one I am aware of suitable for these experiments. I 

 used very pure sugar candy. 



n. 

 25 



0-7558 



50 



0-8425 



100 



0-9091 



200 



0-9500 



400 



0-9742 



