346 DR. BENCE JONES ON THE VARIATIONS IN 



precipitate fell (fig. 2). This remained granular or changed into the crystalline form 

 (fig. 3), according as the phosphate of soda was or was not in excess. If the chloride 

 of calcium was added in excess, the fluid became acid to test-paper ; the precipitate 

 was at first gelatinous, but changed after some hours into crystalline, the fluid be- 

 coming less acid after some time. If phosphate of soda was in excess, the precipitate 

 remained of a mixed granular and crystalline appearance, containing some crystals 

 but more granular phosphate of lime (fig. 4). 



If common phosphate of soda was poured drop by drop into chloride of calcium, 

 a precipitate fell, which was at first gelatinous (fig. 2), the fluid becoming strongly 

 acid to test-paper ; if left to stand, the precipitate became crystalline (fig. 3), and at 

 length lost some or all its acid reaction, which it reacquired again on boiling. 



If common phosphate of soda was dropped into solution of nitrate of lime in excess, 

 the result was the same gelatinous granular precipitate first forming, the same acid 

 reaction, and the same change into the crystalline form on standing. 



If any of these precipitates were separated by filtration, and the clear liquid boiled, 

 a further slight precipitation occurred, which was granular (fig. 2). If the phos- 

 phate of soda was not in excess, the boiling caused an increase in the acid reaction 

 of the liquid. The precipitate which falls when chloride of calcium is added to 

 phosphate of soda, completely dissolves in solution of biphosphate of soda. Such a 

 solution, if heated, gave a plentiful precipitate when boiled ; this was granular, and 

 partly dissolved on cooling ; but if a great excess of biphosphate of soda was added, 

 the precipitate was much less, and crystalline ; and if filtered, but little precipitate 

 again fell on boiling. 



If sulphate of magnesia was added to a solution of biphosphate of soda, no preci- 

 pitate fell ; nor on boiling did any change occur. If but little alkali was added, no 

 precipitation occurred on boiling ; if rather more, a small, highly crystalline preci- 

 pitate fell (fig. 5) ; if still more, heat threw down a plentiful gelatinous granular mass 

 (fig. 2), which most rapidly dissolved on cooling. 



If sulphate of magnesia was added to common phosphate of soda, little or no pre- 

 cipitate occurred, but if boiled a gelatinous precipitate fell; this dissolved as the 

 fluid cooled. Under the microscope it was seen to be amorphous (fig. 2). If it was. 

 in such excess as not entirely to redissolve on cooling, a few drops of biphosphate 

 immediately made the liquid clear. This, if boiled, gave a plentiful precipitate, and 

 more quickly dissolved on cooling than before. If the liquid was very acid from 

 biphosphate of soda, a slight crystalline precipitate fell, consisting of minute rhombic 

 crystals, similar to those which were seen in the experiment with biphosphate of soda 

 (fig. 5). 



If a solution of phosphate of soda was dropped into an excess of sulphate of mag- 

 nesia, after long standing a crystallization of small needles took place (fig. 6), but 

 the fluid did not become acid to test-paper : nor if dropped into an excess of solution 

 of chloride of magnesium was an acid reaction perceptible. 



