SOLUBLE IN NITRATE OF AMMONIA. 297 



ammonia should be weighed out, sufficient to precipi- 

 tate more than the quantity of lime present. It suf- 

 fices for this purpose to multiply the weight of the 

 lime by 2J and to place this weight of pure pulverized 

 oxalate in the liquid which is stirred and left to settle. 

 When the liquid is clear, there should be added two 

 or three drops of oxalate of ammonia, and if there is 

 a precipitate, it is certain there was lime in the mate- 

 rial to be analyzed. There is added, successively and 

 in quantities estimated approximately, solid oxalate 

 of ammonia and a few drops of the dissolved oxalate, 

 in such a manner as to be sure to have an excess of 

 oxalate of ammonia and to add the least possible quan- 

 tity of the solution of the oxalate so as not to increase 

 the quantity of the liquid. It is left to settle for eight 

 or ten hours and then decanted upon a filter. All the 

 oxalate of lime is placed on the filter, by washing it 

 little by little with warm water. The precipitate is 

 then dried, ignited a sufficient number of times, and 

 weighed. This determines the weight of the lime. 

 From this weight increased by that which has already 

 been found, the weight of the lime added to decompose 

 the mineral is subtracted. This gives the weight of 

 the lime existing in the original substance. 



The liquid which remains is evaporated in a platinum 

 capsule, until the fluid is concentrated and syrupy. It 

 contains considerable nitrate of ammonia, a little oxa- 

 late of ammonia, and nitrates of magnesia, manganese, 

 potassa, and soda. It is covered with a glass in such 

 a way as to transform the capsule into a closed vessel, 

 and the saline mixture is heated. The nitrate of am- 

 monia is converted into nitrous oxide, the oxalate is 

 decomposed and volatilized, and there remains in the 

 capsule and on the glass those substances which it is 

 necessary to heat to 300 with the gas or alcohol lamp. 

 1st, nitrates and subnitrates of magnesia and manga- 

 nese; 2d, nitrate of potassa; 3d, nitrate of soda. 



