1820.] Physical Science during the Year 1819. 37 



of which he was capable, and giving results as near precision as 

 the present state of our apparatus will admit. I have reason to 

 be satisfied with these experiments, as, in every case, the new 

 numbers obtained by Berzelius approach nearer to those which 

 I have fixed upon from theoretical considerations as the true 

 numbers denoting the atomic weights of the respective bodies. 

 To expect an accurate coincidence between my numbers and 

 those obtained by actual experiment wo.ild be unrea.sonable. 1 

 consider it as a sutticient indication of at least a very near 

 approach to precision, that in proportion as greater precautions 

 are taken, and greater accuracy attained, in chemical analyses, 

 the numbers obtained approach nearer and nearer to those indi- 

 cated by theory. 



3. Carbonates of Ammonia. — When muriate of ammonia and 

 carbonate of lime are exposed to heat, a salt is obtained usually 

 distino-uished by. the name of subcarbonate of ammonia. This 

 salt has been lately analyzed by Mr. Richard Phillips, and 

 found composed of 



3 atoms carbonic acid. . . = 8*25 or 55*933 



2 atoms ammonia = 4'25 28'813 



2 atoms water = 2-25 15-254 



14-75 100-000 



It would appear from this, that during the distillation of the 

 mixture of sal ammoniac and carbonate of lime, one atom of 

 water and one atom of ammonia are dissipated ; for if nothing 

 were lost, it is obvious that the carbonate obtained would be a 

 compound of 



3 atoms carbonic acid, 



3 atoms ammonia, 



3 atoms water, 



which is evidently the same thing as if it were composed of 



1 atom carbonic acid = 2*750 



1 atom ammonia = 2-125 



1 atom water = 1-125 



6-000 



When this subcarbonate is exposed to the air in a state of 

 powder, it is well known that it loses its odour, and that it is 

 converted into a bicarbonate of ammonia. Mr. Philhps has 

 confirmed this by a new analysis of his own, from which it 

 appears that this bicarbonate is composed of 



2 atoms carbonic acid = 5-500 



1 atom ammonia = 2-125 



2 atoms water = 2-250 



9-875 



