Loss of Energy due to Chemical Union 8fc. 31 



of rubidium were converted into caustic by means of sul- 

 phuric acid followed by baryta. The solution of caustic soda 

 was prepared by adding small fragments of sodium to water 

 in a covered nickel crucible. Chlorate of rubidium could not 

 be used, because it was not sufficiently soluble; carbonic acid, 

 chlorine, and iodine were too insoluble to form solutions of 

 the usual degree of strength, and weaker solutions had to be 

 employed. 



The results are given in series of tables. The quantities of 

 substances used in each single table were chemically equiva- 

 lent to one another, and those of one table were usually so to 

 those of other tables, except in certain cases which the reader 

 will have to observe. " Strong solutions " contained 1 equi- 

 valent weight in grains dissolved in 1800 grains of water ; 

 in consequence of the sparing solubility of carbonic acid, the 

 " weak solutions " were arranged to contain only one tenth 

 that quantity or 1 equivalent weight in 18,000 grains of 

 water. In Tables XVI., XVIII,, XIX., XX., XXII., XXIII., 

 XXIV., XXV., XXVIII., and XXIX. still weaker liquids 

 were used. In all the tables, as the amounts of variation of 

 electromotive force due to difference of atmospheric tempera- 

 ture were usually small (see page 42), and the insertion of 

 the temperatures would enlarge the tables, the temperatures 

 are omitted. 



In most of the tables of Sections A, B, C, and D, the sub- 

 stances are arranged in the usual chemical groups in order to 

 enable the results to be more conveniently compared with the 

 atomic weights, specific gravities, amounts of chemical heat, 

 &c. of the elementary constituents of the compounds. 



The tables of Section A relate to the Formation of Salts 

 from Acids and Alkalies, and give with each pair of substances 

 the separate amounts of electromotive force excited by the 

 acid, the base, and the saline product of their union ; then the 

 mean electromotive force as calculated from those of the two 

 separate substances and corrected for difference of equivalent 

 weight ; the amounts of loss of energy due to the chemical 

 union of the acid and base, and the percentages of such loss 

 upon the calculated mean amounts. In some of these tables, 

 the numbers of Centigrade-gramme units of heat evolved by 

 the chemical union of some of the same ingredients, as deter- 

 mined by J. Thomsen, are given for the purpose of comparison 

 with the amounts of loss of electromotive force. 



The influence of the positive metal was examined by em- 

 ploying several different positive metals with the same solu- 

 tions in different sections of the research. The effects of 

 difference of acid, base, salt, halogen, strength of solution, 



