298 Mr. Griffin on the Constitution of 



mined by the following process. The numbers in column 7 

 show the volume in septems of every solution equivalent to 1 

 test atom of anhydrous acid. Deducting from that number the 

 volume occupied by 1 test atom of anhydrous acid, as quoted 

 in the same horizontal line in column 5, the residue is the 

 quantity of associated water expressed in septems. Dividing 

 this residue by the atomic volume of water, 16*075 the P ro " 

 duct shows the number of atoms of water that occur in 

 combination with 1 atom of the anhydrous acid. 



The range of the experiments recorded in this and the 

 following tables, is from a solution saturated at 62° F. to a 

 solution containing 1° of acid or other substance per deci- 

 gallon, or 1 test atom in 10 imperial gallons of solution. I 

 do not stop at that stage of dilution because the condensing 

 power of the chemical substances is exhausted, for I find no 

 limit to that power. I stop because experiments performed 

 on liquors further diluted do not give results of sufficient ac- 

 curacy for this inquiry. It is impossible to determine the 

 exact specific gravity of solutions running between sp. gr. 

 1-001 and sp. gr. 1-000. 



Observations on some of the prominent features of the Table 

 of Sulphuric Acid. 



Messrs. Playfair and Joule (Philosophical Magazine, vol. 

 xxvii. p. 480) consider the atomic volume of sulphate of water 

 to be equal to twice the atomic volume of water. Deducting 

 the water, this leaves 16-07 as the volume in solution of the 

 anhydrous sulphuric acid. This agrees with a solution of 

 about 160° of chemical strength, but disaccords with every 

 other solution, weaker or stronger. In fact, anhydrous sul- 

 phuric acid has no fixed volume in solution. Its measure 

 extends from + 33*96 septems to —68*41 septems, changing 

 with every change in the composition of its hydrates, so that 

 a single drop of water cannot be added to any solution with- 

 out diminishing the bulk, by increasing the condensing 

 power, of the anhydrous acid. 



The amount of the condensation effected by anhydrous 

 sulphuric acid in its various stages of hydration is remarkable. 

 The atomic volume of the test atom of acid is very nearly 36 

 septems, or 1 cubic inch. With half an atom, or 8 septems 

 of water, it condenses 2f septems. With 1 atom, or 16 

 septems of water, it condenses 5 septems. With 2 atoms, or 

 32 septems of water, it condenses 10 septems. In all these 

 cases the condensation is equal to nearly one-third part of 

 the entire bulk of the water. With 6227 atoms, or 100105 

 septems of water, it condenses 105 septems. In this case 



