448 Mr. Griffin on the Constitution of 



Observations on the Table of Anhydrous Soda. 



The strongest solution of anhydrous soda, prepared at 62° 

 F., has a chemical strength of 700° and a density of 1*4. Its 

 formula is NaO + 9H 2 0. The greatest condensation occurs 

 in this solution, where the test atom of soda effects at once 

 a condensation exceeding its own volume. The atomic mea- 

 sure of the uncombined soda is 19*91 septems, and that of 

 the soda in the strongest solution is — 1*30 septem. Hence 

 a decigallon of this solution contains seven times 391 grs. of 

 anhydrous soda, in addition to more water than would fill the 

 vessel if no soda was present. It is impossible to obtain 

 any solution of soda at 62° F., a decigallon of which does not 

 contain more than a decigallon of water. I have already 

 noticed the fact, that 1000 septems of water, when saturated 

 with anhydrous sulphuric acid, produce 5227 septems of so- 

 lution. By way of contrast, I may state that 1000 septems 

 of water, when saturated with 140 septems of anhydrous 

 soda, produce only 991 septems of solution ; and yet the con- 

 densation effected by 1 test atom of soda in a solution of this 

 kind, is only one-third part of that which it effects in a solu- 

 tion of 1°. At that stage of dilution the condensation effected 

 by 140 septems of anhydrous soda amounts to about 400 

 septems. 



The fraction which + 1 indicates the mean specific gravity 

 of 100° of soda is (1*805-^-50*231 = ) '035934. 



The specific gravity of the saturated solution of 700° or 

 specific gravity 1*4 may be explained thus: — 



1*000000 = specific gravity of water. 

 •251538 = '035934 x 7 atoms, for mean specific gravity. 

 •148470 = 21'21 x 7 atoms, for effects of condensation. 



1*400008 = real specific gravity of solution of 700°. 



In a solution of 300° the density caused by condensation 

 equals that which is produced by the replacement of water 

 by the anhydrous alkali, and in weaker solutions the density 

 induced by condensation is much greater than that occasioned 

 by the replacement of water by alkali, although the uncom- 

 bined alkali possesses nearly three times the density of water. 



When a test atom of caustic soda dissolves in a minimum 

 of water (say 9 test atoms), the condensation it effects is 21 

 septems ; but when it dissolves in a maximum of water (say 

 6226 test atoms), the condensation effected is three times as 

 much. Those chemists who consider that hydrate of soda 

 dissolves in water without combining with it chemically, will, 

 it appears to me, not easily account for this condensation. 



