AMMONIACAL SALTS. 335 



izes, and the volatile salt is progressively evolved until the mass ia 

 quite dry. In maintaining a similar mixture in a fit and constant 

 state of moisture we may in two or three days, under the influence 

 of a temperature of from 68" to 80° F., dissipate the greater portion 

 of the ammonia of the sulphate, and obtain a quantity of sulphate of 

 lime indicating the progress of the reaction. 



It is almost needless to remark that sulphate of lime, placed in a 

 condition of moisture analogous to that of the chalk, undergoes no 

 alteration from the carbonate of ammonia. Thus, in the ordinary 

 circumstances of humidity of cultivated land, it is at least doubtful 

 whether the plaster diffused through it definitively retains the am- 

 monia of the rain-water in the state of sulphate. 



To estimate the sulphate of lime produced by the reaction between 

 the sulphate of ammonia and carbonate of lime, the mixture after 

 having been entirely dried in the air is to be treated with cold water. 

 The lime of the sulphate dissolved is next thrown down by oxalate 

 of ammonia, and computed in the state of carbonate. 



In order to ascertain the presence of sulphate of ammonia the 

 mixture is to be digested in dilute alcohol, which dissolves this salt 

 without taking up sulphate of lime. 



Muriate, phosphate, and oxalate of ammonia comport themselves 

 •IS the sulphate. Carbonate of lime decomposes them under the 

 same circumstances, giving rise to equivalent products.* 



The preceding facts may perhaps tend to reconcile the contra- 

 dictory results obtained in the application of ammoniacal salts as 

 manure. When muriate, phosphate, or sulphate of ammonia is pre- 

 sented to plants, these salts produce no useful effect ; they are ab- 



* 1. 15.4 grains of crystallized sulphate of ammonia incorporated with five or six 

 times its weight of chalk, gave after two days' exposure of the moist mixture in the 

 open air, 12.3 grs. of sulphate of lime. In another experiment 16.0 grs. of sulphate of 

 ammonia were obtained from 13.1 grs. of calcareous sulphate. Now according to the 

 proportions of ammoniacal salt there ought to have been obtained 13 grs. and 14 grs. 

 of sulphate of lime. Thus about 9-lOths of the ammonia contained in the sulphate sub- 

 mitted to experiment had been converted into carbonate. 



2. 16.9 grs. of sulphate of ammonia were mixed with 123.2 grs. of chalk, and frorr 

 924 to 1071 grs. of silicious sand. The mixture was kept moist and exposed to the aii 

 during four days, the temperature ranging from 68* to 80' F. The substance, afte' 

 being dried by the action of the air, was set to digest in weak alcohol ; the alcohol; 

 liquor yielded only an insignificant trace of sulphate of ammonia. There was aboi 

 18.5 grs. of sulphate of lime. 



3. A very simple means of determining the reaction in question consists in plunging 

 a fragment of chalk into a solution of sulphate of ammonia ; the fragment so imbued 

 on being expor=ed to the air emits during several days fumes of carbonate of ammonia. 

 Several bits of chalk moistened in the solution, and exposed by the aid of an asuiratoi 

 to a continuous current of air, afterwards washed in muriatic acid, disengaged enough 

 of ammoniacal vapur to form in the acid nearly 15 grs. of sal-ammoniac. 



4. With a slightly moistened silicious sand were incorporated 30.8 grs. of gypsum 

 the niixture then watered with a solution containing 30.8 grs. of carbonate of ammo 

 nia, was allowed to remain in the air during eight days, having always the consistence 

 and humidity of arable land. At the end of this time it was dried, then treated with 

 weak alcohol ; the alcoholic fluid evaporated left no sulphate of ammonia. 



5. Phosphate of anmionia, mixed with chalk, and kept in a moist state for som» 

 days, comported itself exactly as the sulphate in the same circumstances; 9-lOthsof 

 the ammoniacal phosphate were converted into phosphate of lime. 



6. The reaction of oxalate of ammonia upon chalk is visible even when the mixtun 

 is well watered ; this is explained indeed by the powerful afllnity of oxalic acid fq 

 lime. The totality of the alkaline oxalate is promptly changed into oxalate of liin< 

 ftD-* carbonate of ammonia. 



