106 On Oxalic ^cid. 



Bergmann states the composition of oxalate of lime as 

 fallows ; 



Acid - - 48 

 Lime - - 46 

 Water - - 6 



100* 



His method was to dissolve a determinate quantity of cal- 

 careous spar in nitric acid, and then to precipitate the lime 

 by oxalic acid. 100 parts of calcareous spar thus dissolved, 

 require, according to him, 82 parts of crystallized acid to 

 precipitate them. But there must have been some mistake 

 in this experiment ; for, according to my trials, (provided 

 the nitric acid be carefully neutralized by ammonia as it is 

 evolved,) no less than 1 17 grains of oxalic acid would have 

 been required, and at least 145 grains of oxalate of lime 

 would have been obtained instead of the U9, which was 

 the result of Bergmann's experiment. It is obvious thi^t 

 Bergmann did not precipitate all the lime. He added ox- 

 alic acid till it ceased to produce any effect on the solution 

 from the great excess of nitric acid evolved ; and then took 

 it for granted that all the lime was separated. But had he 

 added ammonia, he would have got an additional quantity 

 of oxalate of lime, and the precipitation would have re- 

 commenced upon adding more oxalic acid. This explana- 

 tion accounts in a satisfactory manner for the difference be- 

 tween Berimiann's statement of the composition of oxalate 

 of lime, and mine. 



2. Though the preceding experiment was made with care, 

 vet as some of the most important of the lollowing observa- 

 tions in some measure rest upon the analysis of oxalate of 

 lime, I ihoucht it worth while to verify that analysis in the 

 following manner : 



100 sirains of crystallized oxalic acid were dissolved in 

 1000 strains of water, making a solution which weighed 

 } 100 grains. 



It is obvioiis that everv 100 grains of the above solution 

 contained 9-09 grains of crystal of oxalic acid, equivalent, 



♦ Opusc. i. 26'2. 



according 



