Scientific Intelligence. 



strictness the sec- 



-.. ^-. a slight ^omVi^ of 



the heat, generally an absorption of lieat, but this amounts to only 

 a couple of thousandths of the heat of neutralization. In the case 

 of fluohydric acid we find an exception, since the second molecule 

 of acid produces an absorption of two per cent of the heat of 

 neutralization. This fact and the existence of the acid fluoride of 

 sodium make it doubtful whether fluohydric acid belongs to the 

 mono-basic acids. The numbers for meta-phosphoric and hypo- 

 phosphorous acid also exhibit a slight toning of the heat (about 

 1 pr. ct.) for the second molecule of acid. But since the numbers 

 for the first acid cannot be sharply determined in consequence of 

 its great liability to change, and since the number for two mole- 

 cules of the second were accidentally determined by only one 

 experiment, I lay no stress on this deviation from the rule. In 

 the case of fluohydric acid, however, the deviation is fully i'^- 

 tablished. 



(6.) The bibasic acids which contain two atoms of hydrogen re- 

 placeable by sodium may be divided into g ' ' '■ 



"" the ^'-^ " ' ■ ' • ' - " 



hyd 



The first group embraces the bibasic hydrogen acids— fluosilico- 

 hydric acid, SiFgHg, and chlorplatinhydrie acid, PtClfiHg; in 

 these there is no noteworthy difference in the quantity of heat 

 which the first and the second molecule of sodic hydrate produ- 

 ces ; they behave therefore like the monobasic hydrogen acids, 

 only the evolution of heat for one molecule of acid increases pro- 

 portionably to the quantity of soda, up to the second molecule of 

 sodic hydrate. 



The second group includes sulphuric, seleriic, oxalic and tartaric 

 ^^T- V"^ tbe neutralization of these acids the first molecule of 

 ^^1, iSj*^^^^^ P^«<^«ces a less degree of heat than the seconi 

 Ine difterence amounts to 5 to 1800 units.* 



The third group embraces sulphurous, selenious, carbonic and 

 bone acids. In the neutralization of these »cids the first molecule 

 ot sodic hydrate produces a greater degree of heat than the sec- 

 ond: the difference amounts to from 18 .. to 28 



Sodic hyd Sulphurous acid. Selenious acid. Carbonic acid. Boric acid. 



; acid, phosphorous acid and proba- 



cnU^ r.^, "- - - reaction of the normal salts of the 



acids, ot the second group upon the corre8|)oiiding acids an absorp- 

 " """ 8 is easily seen, while the normal salts of the 



