M. Chizinski on the Influence of Masses in Chemical Affinity. 389 



quantities of chloride of calcium be added, with an increasing 

 percentage of lime in the solution the proportion of lime in the 

 precipitates also increases. And conversely, when the lime and 

 the phosphoric acids are kept constant and the magnesia is in- 

 creased, the percentage of magnesia in the precipitate increases. 



As regards changes in the composition of the precipitate, 

 Chizinski arrived at results differing from those which Debus 

 obtained from his experiments on the affinity of carbonic acid 

 for lime and baryta. Debus concluded that these changes took 

 place by starts ; Chizinski that they took place gradually and 

 steadily. The quantity of any of the bases present in the pre- 

 cipitates increases if this is increased in the solution, but not, 

 as Berthollet taught, proportionally to this increase. The com- 

 position of the precipitate varies in a rather complex manner with 

 the composition of the solution. 



If in the solution there are equivalent quantities of calcium 

 and magnesium, more lime than magnesia is precipitated. Hence 

 it may be assumed that, cceteris paribus, lime has a greater affi- 

 nity for phosphoric acid than magnesia. But with equivalent 

 quantities of both bases in solution, according as the mass of 

 both as compared with the phosphoric acid is greater or smaller, 

 the composition of the precipitate varies. If the solution for one 

 molecule of phosphoric acid (H 3 P0 4 = 98) only contains one mo- 

 lecule of each base (that is, CaCl 2 = 110*9.2 and Mg Cl 2 = 94'92), 

 the lime in the precipitate only slightly exceeds the magnesia ; 

 the sum of both is not quite equal to 3 equivalents (1 equiva- 

 lent = half an atom of biatomic elements). Hence the preci- 

 pitate must contain some ammoniacal phosphate of magnesium. 

 If the quantity of bases in the solution is increased, the mag- 

 nesia in the precipitate first decreases and then increases ; the 

 lime, however, continually and materially increases until, using 

 lOCaCPand lOMgCl 2 for 1H 3 P9 4 , the precipitates contain 

 3 equivalents of lime and 1*1 equivalent of magnesia — that is, 

 together more than 4 equivalents of base. These precipitates 

 are basic phosphates, analogous to Wagnerite and Apatite, ex- 

 cepting that they contain no chlorine or fluorine, but oxygen 

 instead. 



If in the solution there is always one molecule of MgCl 2 for 

 one molecule of H 3 PO 4 , and the quantity of calcium salt in the 

 various precipitates increases from one to ten molecules, not only 

 does the proportion of lime in the precipitates increase while the 

 magnesia decreases, but the sum of both bases increases from 

 less than 3 to more than 4 equivalents for one molecule of phos- 

 phoric acid. 



If, on the other hand, the proportion of lime in the solutions 

 is constant (1*5 molecule =3 equivalents), and if the quantity of 

 magnesia is increased from one molecule for one molecule H 3 PO 4 



