Dr. Holzmann on some Cerium Compounds. 217 



agonal plates, frequently of one or two centimetres in diameter, 

 were recrystallized three or four times, and the formation of large 

 crystals prevented by stirring. For analysis, the salt was dried 

 over caustic lime and chloride of calcium. 



(1) 06942 grm., treated with recently precipitated oxide of 

 silver, gave, after precipitating the filtered liquid with hydrochlo- 

 ric acid, 0*4156 Ag CI. The liquid filtered off from the chloride 

 of silver gave with ammonia and phosphate of sodium, O1690 

 (MgO) 2 P0 5 . After treating the oxide of silver on the filter 

 with hydrochloric acid, the liquid gave, on precipitation with 

 oxalate of ammonium and ignition of the oxalate of cerium, 

 0-1647 Ce 3 4 *. 



(2) 0-52 grm., dissolved in water and precipitated by oxalate 

 of ammonium, gave 0-1235 Ce 3 4 : the filtrate gave with am- 

 monia and phosphate of sodium 0-1237 (MgO) 2 P0 5 . 



(3) 0-4527 grm. gave, after Dumas^s method (the substance 

 in a platinum tray), 43 - 09 cubic centims. nitrogen of 0° C, and 

 760 millims. pressure. The residue, treated with concentrated 

 nitric acid and precipitated by oxalate of ammonium, gave 

 0*1078 Ce 3 4 ; and the filtrate with ammonia and phosphate of 

 sodium 0-1093 (MgO) 2 P0 5 . 



(4) 0*9543 grm., dissolved in water and precipitated with 

 oxalate of ammonium, gave 0'2307 Ce 3 4 , and the filtrate on 

 evaporation and ignition 0*0778 MgO. 



(5) 0'5343 grm., treated in the same manner, gave 0-1285 

 Ce 3 4 and 0*045 MgO. 



These numbers lead to the formula 



CeO, N0 5 + Mg 0, N0 5 + 6HO. 



Theory. 



Experiment. 



CeO . 



. 54 



22-88 



MgO . 



. 20 



8-48 



N05 . 



. 54 



22-88 



NO* . 



. 54 



22-88 



6 HO . 



. 54 



22-88 





236 



10000 



(1) (2) (3) (4) (5) 



22 61 22 63 2269 2304 2292 



8-77 8-58 8-70 8-15 8-42 



22-53 



4613 



The double nitrate of cerium and ammonium has not been prepared 

 by Lange. It is obtained by mixing equal parts of rather con- 

 centrated solutions of the two salts, concentrating the liquid 

 on the water-bath, and allowing it to cool over chloride of 

 calcium and caustic lime. If the liquid cools gradually, it soli- 

 difies to a radiated crystalline mass ; but if cooled quickly by 



* It appears from this that only the nitrate of cerium gives up its acid 

 to the oxide of silver ; the quantity of chloride of silver found corresponds 

 therefore only to half the quantity of nitric acid contained in the salt. 



Phil. Mag. S. 4. Vol. 22. No. 146. Sept. 1861. Q 



