456 Mr. Griffin on the Constitution of 



of solution of 100°, or 1 test atom of ammonia per decigallon, 

 is calculated thus : — 



42-857143 septems=bulk of 1 test-atom of N 2 H 6 . 



957*142857 ... = water required to complete 1000 sept. 

 6700* grs. = weight of that measure of water. 



212-5 ... = weight of 1 test atom of N 2 H 6 . 



6912-5 ... = weight of 1000 septems of solution. 



6912*5 

 Corresponding specific gravity = -987500. 



The ratio of N 2 H 6 by weight is 212 ' 5 = -030741. 



oy i — *«> 



We have thus the weight and the volume of the water, the 

 weight and the volume of the ammonia, and the weight and vo- 

 lume of the resulting solution : in short, all the details neces- 

 sary to give a complete knowledge of the physical constitu- 

 tion of the compound. 



The other solutions were all calculated in the same way. 



The weight of 1°, the hundredth part of a test atom, of 

 ammonia, is 2-125 grs. ; its volume at 62° F. is precisely 

 equal to that of 3 grs. of water. Every degree of ammonia, 

 added to an aqueous solution, displaces 3 grs. of water, re- 

 duces the weight of a decigallon of solution to the extent of 

 3 —2*125 m *875 grs., and lessens the specific gravity by 

 •000125. From this principle proceed two important prac- 

 tical rules : — 



I. Given, the specific gravity of a solution of ammonia, to 

 find its chemical strength. 



Deduct the specific gravity from 1*000000, and divide the 

 remainder by -000125. The product is the chemical strength 

 expressed in degrees. 



II. Given, the chemical strength of a solution of ammonia, 

 to find its specific gravity. 



Express the chemical strength in degrees ; multiply it by 

 •000125, and deduct the product from 1*000000. The re- 

 mainder is the required specific gravity. 



The four solutions at the head of the list, separated from the 

 others by a horizontal line, are such as do not exist at the 

 temperature of 62° F. The first line is anhydrous ammonia, 

 assumed to retain its usual volume at 62° F. though free 

 from water. The second line is the supposititious oxide of 

 ammonium = N 2 H 8 0. The third line is the hydrate of that 

 assumed oxide = N 2 H 8 4- H 2 0, corresponding to caustic 

 potash. The fourth line represents the last compound with 

 an additional atom of water =N 2 H s O + 2H 2 0. The chemical 

 strength of this third hydrate is 1098°. Now I have procured 



