132 Mr. J. J. Griffin's Arithmetical Analysis of 



perfect combustion. This relation, according to weight and 

 volume, is given in the second and third columns. 



For example, 100 volumes being taken, the Lancashire 

 coal gives out more heat than the same volume of Edinburgh 

 coal by a quantity expressed by 17'91 : and 100 parts by 

 weight being taken, the former coal surpasses the latter in 

 the heat evolved by the quantity expressed by 17'83. 



XVIII. Arithmetical Analysis of mixed Salts of Potassium and 

 Sodium. By John Joseph Griffin, Author qf^^ Chemical 

 Recreations."* 



Analysis of Chlorides. 



METHOD. 



a. 'liyEIGH the chlorides. 



1). ^^ Dissolve the chlorides, precipitate with nitrate of 

 silver, and weigh the chloride of silver. 



c. Multiply the weight of the mixed alkaline chlorides a, 



by 1-92404.. 



d. Subtract the product of the multiplication c, from the 



weight of the chloride of silver h. 

 c. Divide the residue of the subtraction rf, by 0*52201. 



f. The product of the division ^, is the weight of the chloride 



of sodium contained in the mixture a. 



g. The dilFerence between the weight of the mixed chlorides 



a, and that of the chloride of sodium^ is the weight of 

 the chloride of potassium. 

 Explanation. — The quantity of chloride of silver producible 

 by chloride of sodium above the quantity producible by chlo- 

 ride of potassium, is 0*52201 for every unit of the given chlo- 

 ride of sodium. For, 



1 of chloride of sodium produces of chloride \ 2-44605 



of silver J 



1 of chloride of potassium produces of chlo-\ 1.92404 

 ride of silver J 



The excess being = 0*52201 



Consequently, in any quantity of chloride of silver pro- 

 duced by a mixture of chloride of sodium and chloride of 

 potassium, we have 



First, as much chloride of silver as is producible by a quan- 

 tity of chloride of potassium of equal weight to the given 

 mixture of chlorides ; and 



Secondly, as much more chloride of silver as is equal to 



* Communicated by the Author : a paper on indirect chemical analysis, 

 by Dr. G. Bird, will be found in vol. xii. p. 229. 



