1821.] Atomic Weight of various Metals and Acids. 135 



Thus the equivalent number for oxalic acid in that salt is only 

 4*595 by Berzelius's own analysis. The same remark applies to 

 all the oxalates which he has given in his table. 



Now that we are acquainted with the true atomic weight of 

 lime, and with the true composition of calcareous spar, there is 

 no great difficulty in determining the true atomic weight of 

 oxalic acid with rigid accuracy. The following experiments., 

 which I have often verified, leave no doubts whatever upon the 

 subject. 



It is well known that oxalic acid usually is crystallized in flat 

 four-sided rectangular prisms. These crystals constitute a defi- 

 nite compound of pure oxalic acid and water, and, therefore, 

 are entitled to the name of hydrate of oxalic acid. As these 

 crystals are always rigidly the same in their composition, it will 

 be safest and most satisfactory to employ them in order to settle 

 the equivalent number for oxalic acid. Nine grains of the crys- 

 tals of oxalic acid were dissolved in a little water, and the solu- 

 tion was saturated with ammonia, gently evaporated to dryness, 

 and the residual oxalate of ammonia redissolved in distilled 

 water. 



The reader will please to recollect, that I showed in a former 

 paper that calcareous spar is composed of 



Lime 35 



Carbonic acid 2-75 



625 



And that an atom of lime weighs 3 - 5. 



6 - 25 grains of pure calcareous spar were dissolved in muriatic 

 acid, the solution was gently evaporated to dryness, and the dry 

 Bait redissolved in distilled water. These two solutions were 

 mixed together. Oxalate of lime immediately precipitated. The 

 supernatant liquor, as soon as it became clear, was tested by 

 oxalate of ammonia and muriate of lime ; but it was not the least 

 disturbed by either of these reagents. Hence it is evident that 

 it contained neither oxalic acid nor lime ; consequently the 

 whole of these two substances which had been in solution had 

 precipitated in the state of oxalate of lime. 



It is clear from this experiment, that nine grains of crystallized 

 oxalic acid contain a quantity of acid capable of exactly neutral- 

 izing 3*5 grs. of lime. 



The oxalate of lime formed in this experiment was dried in the 

 temperature of about 100° ; in this state, it weighed 103 grs. 

 It was now placed on the sand-bath, and exposed for two hours 

 to a temperature at first of 450°, but rising gradually to 500°, 

 or, perhaps, a few degrees higher. The weight was now reduced 

 to 8-03 grs. When thus reduced in weight, it still retained all 

 the properties of oxalate of lime. Another hour's exposure to a 

 heat of about 550° reduced the weight to 8-015 grs. Beyond 



