Products of the Distillation of Meconic Acid. 129 



In this, as well as in some other respects, it very closely 

 resembles pyrogallic acid, except that pyromeconic acid is not 

 so easily oxidable as pyrogallic acid. 



A considerable quantity of an alcoholic solution of potash 

 was added to a portion of pyromeconic acid, also dissolved in 

 hot spirits of wine. The liquid became slightly yellow, and 

 on cooling deposited crystals of the acid containing only a 

 very little potash. The crystals were pressed between folds 

 of blotting-paper and re-dissolved, and on crystallizing them 

 a second time they contained merely a trace of potash, and 

 that obviously owing to the extreme solubility of both the 

 acid and the potash, which rendered their complete separation 

 a matter of some difficulty. A great excess of ammonia was 

 next added to an alcoholic solution of pyromeconic acid, which 

 also soon rendered it slightly yellow. It was dried under the. 

 air-pump. The pyromeconic acid crystallized out, with its 

 properties apparently unaltered. It gave no indication of 

 containing ammonia when boiled with either hydrate of lime 

 or potash. When subjected to analysis — 



0*3498 gramme of substance gave 0*6745 of carbonic acid 

 and 0*11 of water. 



Pyromeconic acid. — Calculated numbers. 



Carbon . . 53-31 54*046 



Hydrogen . 3*49 3*530 



Oxygen . . 43*20 42-424 



100*00 100*000 



It is obvious, from a comparison of the result of this ana- 

 lysis with the calculated numbers of pyromeconic acid, that 

 the ammonia had not combined with the acid, which, if al- 

 tered at all, had only been slightly oxidated. 



The only salt of pyromeconic acid of which any account 

 has hitherto been published, is the lead salt. It was formed 

 by Robiquet by adding hydrated oxide of lead to a hot solu- 

 tion of pyromeconic acid. When the acid was nearly satu- 

 rated, the lead compound precipitated ; Robiquet found the 

 salt to be anhydrous, and to consist of C 10 H 3 5 -f PbO. 



Pyromeconate of Copper. 



When an excess of hydrated oxide of copper is boiled for 

 a short time with pyromeconic acid, the solution becomes of 

 a bright green colour, and when filtered an emerald-green 

 coloured salt is deposited on cooling. It crystallizes in long 

 slender delicate needles, which are very brittle. The crystals 

 require a good deal of hot water to dissolve them, and are very 

 slightly soluble in cold water, or alcohol in either hot or cold. 

 When dried under the air-pump, and then kept for some time 



Phil. Mag. S. 3. Vol. 24. No. 157. Feb. 1844. K 



