52 ON A GENERAL METHOD OF SUBSTITUTING 
upwards, and by slight tapping a passage opened throughout the w and so 
of the tube, while the pieces of lead projecting above the surface meltewethat _ 
application of heat, and by exposing a metallic surface during the time combustion 
was going on, served to retain all the iodine. 
The results of analysis are as follows: The hydrogen of No. 1 was not weighed, 
as, from its combustion being effected in the ordinary way without lead, the small 
end of the chloride of calcium tube was completely covered with small plates of 
iodine. 
No. 1. 4:893 grains substance burned with chromate of lead, gave 
4620 ... carbonic acid. 
No. 2. 7-298 grains substance burned with chromate of lead, litharge, and metallic lead, gave 
6-759 +.» carbonic acid, and 
‘975 ... water. 
No. 3. 6°85 grains substance heated with carbonate of potash, gave 
6-707... iodide of silver. 
No. 1. No. 2. Calculation. 
poe Ee 
Carbon, . . . 20°750 25:25 25:19 C,, 60 
Hydrogen, on 1-48 1:26 6s, 3 
Oxycens ata: oo 20:17 860, 48 
Todine,. . . . 52:909 oe 53:38 I 127-1 
100-000 100-00 100-00 238-1 
These results correspond exactly with the formula, C,, H, 10,+HO. 
Iodopyromeconic 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. 
Todopyromeconate of baryta is readily prepared by mixing together alcoholic 
solutions of acetate of baryta, and of the acid made slightly alkaline with am- 
monia. 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 .-- sulphate of baryta. 
which corresponds to the formula, BaO C,, H, 10,+HO, as shown by the follow- 
ing calculation :-— 
Experiment. Calculation. 
ae 
Carbons42 ree ah 19-068 Co 60 
Hydrogen, . . te 954 H, 3 
Oxvoens, io sais ise 15°255 O, 48 
Todine; «i. 4.982 oa 40°394 I 127-10 
Baryta, . . . 23°84 24329 Ba O 76:55 
100-00 100-000 314:65 
