232 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



calcium carbonate, filtered, and treated with an equal vol- 

 ume of alcohol. After twelve hours the greater part of the 

 calcium salt had completely separated. At first the author 

 supposed this to be calcium glycerate in a pure form; but 

 by solution in warm water it left a residue, which only dis- 

 solved by long boiling. This residue, about a tenth part of 

 the entire salt in amount, was filtered off, washed, and dried. 

 It appeared as a white powder, non-crystalline. Upon anal- 

 ysis this powder gave numbers agreeing very closely with 

 calcium tartronate. Conversion into the acid confirmed this 

 supposition. Under the glass the acid crystallized in tables 

 having the form of the tartronic acid from nitro-tartaric acid. 

 This view was confirmed by the results of its elementary 

 analysis. 35 C, VIII., 1456, Nov., 1875. 



ACTION OF WEAK ACIDS ON SALTS OF STRONGER ONES. 



The importance in chemical dynamics of the question, 

 "What is the condition in which several substances exist when 

 in solution ? has been oftener recognized than experimentally 

 investigated. Bergmann advanced long ago the theory 

 that is now generally maintained, i. e., that universally 

 bodies combined according to the strength of their chemism. 

 Berthollet, on the other hand, asserted that when different 

 salts were dissolved together, as many bodies were formed as 

 by the exchange of acids and bases were possible. Among 

 the experiments made to settle the question, those of Betten- 

 dorff are perhaps the most satisfactory. By studying the 

 action of light on certain solutions, he was led to decide for 

 the view of Bergmann. Hubner and Wiesinger, not regard- 

 ing these experiments of Bettendorff as sufficiently nume- 

 rous or comprehensive, have made use of a different method 

 for solving the problem by making the distinct proposition : 

 Can a dissolved acid expel a stronger one from its salts in 

 solution without any substance separating from the solu- 

 tion ? For these experiments they used benzoic acid for the 

 weaker and nitrobenzoic acid for the stronger acid. They 

 are both monobasic, are easily obtained pure, are easily sep- 

 arated from each other and from their salts, and can be rec- 

 ognized with certainty. They differ only apparently in the 

 strength of their chemism. In the qualitative experiments, 

 barium nitrobenzoate and free benzoic acid were dissolved 



