Aqueous Solutions of Acids and Alkalies. 



463 



The fraction which + 1 indicates the mean specific gravity 

 of 100° of sal-ammoniac is (•53257-r-16'07l=) '033150. 



It follows from what has been stated, that the real specific 

 gravity of solutions of sal-ammoniac must be less than the 

 mean specific gravity when the chemical strength is above 

 12°, and greater than the mean specific gravity when the 

 chemical strength is below 12°. 



Examples : — 



Mean sp. gr. 

 Deduct . . 



Real sp. gr. . 1-028660 



100° 

 1-033150 

 0-004490 



Mean sp. gr. 

 Add . . . 



Real sp. gr. . 1-003515 



10° 



1-003315 



0-000200 



The following experiments were made to determine the 

 correctness of the number assumed for the atomic weight of 

 sal-ammoniac. 



1. A solution of 66- 763 grs. of sal-ammoniac mixed with a 

 solution of 212*864 grs. of crystallized nitrate of silver, re- 

 quired half a septem of solution of nitrate of silver of 10° to 

 complete the precipitation. 



2. A solution of 66*96 grs. of sal-ammoniac (Berzelius's 

 number) mixed with a solution of 212*864 grs. of nitrate of 

 silver, required 3 septems of solution of nitrate of silver of 10° 

 to complete the precipitation. 



These experiments tend to prove that, taking for granted 

 the accuracy of Berzelius's number for nitrate of silver, his 

 number for sal-ammoniac is too high. But if, as the above 

 experiments seem to show, 667*63 is the correct number for 

 sal-ammoniac, then 212-5 is the correct number for ammonia, 

 as I have assumed it to be in Table XVI. 



