1815.] Elements of Orga7iic Nature are comUncd. Of 



3. Oxalic acid. — My former analytical experiments on the oxa- 

 late of lead, indicate 25'2 of oxalic acid in 100 of oxalate of lead. 

 The analysis was made by combustion, but without attending to 

 the lead which was reduced and concealed in the oxide of lead ob- 

 tained. Later experiments on four parts of oxalate of lead gave 

 me a loss amounting to 0-9835 ; the oxide being dissolved in 

 vinegar, 0-095 of metallic lead remained. This indicates 0-009 of 

 oxygen, which must be subtrjcted from the loss in order to obtaia 

 the true quantity of acid; of course it amounted to 0-9816 or 

 24-54 per cent, of the weight of the oxalate. This result was 

 constant in various experiments. The oxalate of lead then is com-- 

 posed of 



Oxalic acid 24*54 100 



Oxide of lead 75-46 307*5 



100-00 



But 307-5 of oxalate of lead contain 22*062 of oxygen. And 

 •ince according to my old experiments on oxalic acid, it contains 

 three times as much oxygen as the base, it follows that it ought to 

 contain 66 186 per cent. 



I mentioned before that the analyses which I made by means o£ 

 the brown oxide of lead gave me too little oxygen and too much 

 hydrogen and carbon. The result of one of these experiments on 

 oxalic acid was 0*66 per cent of hydrogen, 34-34 of carbon, and 

 64-99 of oxygen. 



In my repetitions by my new method, I burnt four parts of 

 oxalate of lead with two parts of hyperoxymuriate of potash. The 

 quantity of water produced weighed only 019; hence I suspected 

 that this oxalate, which had been strongly heated, might have been 

 partly decomposed. I therefore repeated the experiment with an 

 oxalate that had been dried in a temperature below 212°. I ob- 

 tained exactly the same result. I next suspected that I had taken 

 too little hyperoxymuriate of potash, in consequence of which 

 some empyreuniatic oil might have been formed, though no trace 

 of it appeared in the water. I therefore burnt two parts of oxalate 

 of lead with two parts of of hyperoxymuriate. I obtained 0*004 

 of water in the receiver, and 0-001 in the tube witii the muriate of 

 lime. So that the result was almost exactly the same, giving 0-02 

 instead of 0-019 of water from four of oxalate. These four parts 

 contain 9816 of oxalic acid; hence it follows, that this acid con- 

 tains only O-2'l, or 0-24 per cent, of hydrogen. 



The carbonic acid produced weighed from 1138 to 1'140, which 

 makes 32-16 [)er cent, of carbon. A little of the carbonic acid 

 remained, combined witii the soda as in other experiments; but 

 this quantity could not be determined, because a portion of the 

 oxide of lead was converted into minium, and gave a red colour to 

 the burnt mass. The colour was the same when 1 endeavoured to 



Vol. V. N° 11. G 



