476 



On the Nature of Solution. 



strength in terms of the number of grammes of sugar in 100 

 cub. centim. of solution, then there are indications of regu- 

 larity. By a very obvious method of calculation this trans- 

 formation may be effected. The ordinary tables when so 

 treated exhibit some departure from regularity. 



We have undertaken a revision of the table and our result 

 is that these departures from regularity are experimental 

 errors. 



Our results are as follows : — 





jSTumber of grms. 









of Cane-iSugar in 



Specific Gravity. 



i. 





litre of solution. 







° Fahr. 









f65-5 



1-341 



1000-52 



•3878 



54 



1-341 



1000-52 



•3878 



[537 



1-341 



1000-52 



•3878 



53-7 



9-878 



1003-84 



•3887 



560 



104-580 



104060 



•3882 



59-0 



749-50 



1282-00 



•3762 



In these experiments we have compared the weight of the 

 sugar-solutions w r ith the weight of an equal volume of dis- 

 tilled water at the same temperature as the sugar-solution, 

 and in each instance have used a half-litre specific-gravity 

 bottle*, except in the last experiment. 



The last measurement was made with a 100 cub. centim. 

 bottle, and has not the same 'claim to be considered highly 

 accurate as the other five measurements ; and we attribute 

 the slight difference in that case to experimental error, and to 

 another cause which may be considered hereafter. 



The value of i for sugar we find therefore to be '388, and 

 it is constant over a very wide range, viz., from 1 grm. of 

 sugar per litre of solution up to 750 grm. of sugar per litre 

 of solution. 



The specific gravity of solid sugar required in order to 

 make « 1 = , 388 is 1*634. The specific gravity of sugar is 

 given in the text-books as l*606f , which would make i 1 = *3773. 



Sugar, therefore, presents an example of equality between 

 i and i ± ; that is to say, its solutions in water occupy exactly 

 the same volume as the separate water and sugar which form 

 them. 



At the beginning of this paper we called attention to Dal- 

 ton's discovery of the contraction which takes place when 



* Vide Wanklyn's • Water Analysis ' (Kegan Paul, Trench, and Triibnerj, 

 eighth edition, p. 78. 

 t Vide Watts's < Dictionary of Chemistry,' vol. v. p. 470. 



