SPECIFIC GRAVITY AND DISPLACEMENT OF SOME SALINE SOLUTIONS. 5 



PAR. , , PAGE 



35. Discussion of tables of Class B, dealing with the exactness of the results. 103 



36-37. Discussion of tables of Class C, dealing with the specific gravities of the solutions. Dis- 104 



cussion of tables of Class D, dealing with increments of displacement, and the effect on 

 the solutions of salts of the double ennead (MR, MRO3) for which m = 1/16 is shown in 

 a table and a diagram. The tables of Class E exhibit the comparative volumetric effect 

 produced by dissolving different quantities of different salts in 1000 grams of water. 

 Each entry in these tables is derived from the corresponding entry, v, in the corre- 

 sponding table of Class D by increasing it in the proportion m: 1, whence we obtain 

 the value of vjm. 



38. Contains a table giving the specific gravities and the increments of displacement for solu- 105 



tions of all the salts of the double ennead (MR, MRO3) for which «i = l/16. The 

 values of the increments of displacement are also exhibited graphically in a diagram. 



SECTION VII. 



The Displacement of the Solutions. 



39. The changes of displacement produced in a constant quantity of water by the dissolution 107 



of successive quantities of a salt in it are compared with those which would take 

 place under one of two hypotheses. 



40. First Hypothesis. — It is assumed that, when a quantity of salt, insufficient for saturation, 108 



is dissolved in a quantity of water, it takes possession of the quantity of water which 

 it requires in order to produce a saturated solution, and saturates it, after which the 

 saturated solution disseminates itself through the remaining water, forming a simple 

 mixture with it. If this law is followed by the solutions of a particular salt, then equal 

 increments of salt dissolved in a constant quantity of water produce equal increments 

 in the displacement of the solutions. This is expressed by the equation 



■ — = Const. 

 an 



41. Second Hypothesis. — It is assumed that, when a quantity of salt, insufficient to produce 108 



saturation, is dissolved in a quantity of water, it exercises no selection, but salinifies 

 every particle of the water alike, producing a homogeneous solution of uniform concen- 

 tration ; and that, when a second quantity of salt, equal to the first, is dissolved in this 

 solution, it intensifies its salinity uniformly and produces an increased displacement, 

 which bears the same proportion to that of the first solution as the displacement of the 

 first solution bore to that of the original quantity of water ; further, that when a third 

 equal quantity of salt is added to the solution of the second quantity, it intensifies its 

 salinity uniformly and produces an increased displacement, which bears the same relation 

 to that of the second solution as the displacement of the second solution bore to that of 

 the first, and as that of the first bore to that of the original water ; and so on. Con- 

 formity with this law is expressed by the equation 



^i2§^ = Const. 

 an 



42. A table for a hypothetical case is given, which affords the means of comparing the effect 110 



produced by diluting or concentrating a given solution with that which would be pro- 

 duced if it took place in terms of the first or second of these hypotheses. 



43. When the tables in this memoir are studied, it is found that in the solutions of the majority 111 



of the salts the values of di^jdm and vjm reach a minimum for the values of m in the 



