Iodine for Hydrogen in Organic Compounds. 205 



calcium tube was completely covered with small plates of 

 iodine. 



I. 4-893 grains substance, burned with chromate of lead, gave 

 4*620 grains carbonic acid. 



II. 7*298 grains substance, burned with chromate of lead> 

 litharge, and metallic lead, gave 6*759 grains carbonic acid and 

 •975 grains water. 



III. 6*85 grains substance, heated with carbonate of potash^ 

 gave 6-707 grains iodide of silver. 



Calculation. 



100-000 100-00 



100-00 



2381 



( 



These results correspond exactly with the formula C^^H^IO^ 

 + H0. 



lodopyromeconic acid is monobasic, and forms salts, of which 

 I have minutely examined only those of baryta and lead. It 

 does not appear to form an ammonia salt. 



lodopyromeconate of baryta is readily prepared by mixing 

 together alcoholic solutions of acetate of baryta, and of the acid 

 made slightly alkaline with ammonia. After a short time it 

 deposits a fine network of delicate crystals, of little solubility 

 either in cold or hot water or alcohol. It is alkaline to litmus 

 paper, and at 212° it suffers no loss of weight. 



The following result was obtained on igniting the salt with 

 sulphuric acid: — 4-49 grains substance gave 1*63 grains of 

 sulphate of baryta, which corresponds to the formula BaO^ 

 (jiog2jQ5_j.jjQ^ as shown by the following calculation : — 



Carbon . , 

 Hydrogen 

 Oxygen . 

 Iodine . 

 Baryta . 



Experiment. 



23-84 

 100-00 



100-000 



314-65 



lodopyromeconate of lead is readily obtained as a fine colour- 

 less amorphous precipitate, on mixing alcoholic solutions of the 

 acid and acetate of lead, with the addition of a small quantity of 



