FORMIC ACID. 82? 



wards shown by Malaguti, to be a mixture of formiate of oxide 

 of methyl and a particular substance which he named methylal. 

 To purify the methylal from formiate of oxide of methyl, the 

 latter must be decomposed entirely by hydrate of potash. 



Methylal is an ethereal colourless liquid of a very agreeable 

 aromatic odour ; it is miscible with 3 parts of water, and may 

 be separated from that liquid by chloride of calcium or hydrate 

 of potash. It is very inflammable, and burns with a white 

 flame. The density of methylal is 0.8551 ; its boiling point 

 107.6 (42 centig.) ; its combining measure contains 4 vo- 

 lumes. Methylal may be represented as a compound of 1 atom 

 of hydrate of oxide of formyl with 2 atoms of oxide of methyl 

 =C 2 HO, HO + 2C 2 H 3 O. M. Regnaulthas explained its for- 

 mation by supposing that 3 atoms of oxide of methyl, formed 

 by the action of sulphuric acid upon hydrate of oxide of methyl, 

 group together so as to form a single molecule=C 6 H 9 O 3 ; the 

 last exposed to the oxidating action of peroxide of manganese 

 loses I atom of hydrogen, which is replaced by 1 atom of 

 oxygen, and consequently the compound C 6 H 8 O 4 is produced. 

 The formation of acetal which corresponds with methylal in the 

 acetyl series is explained by Regnault in the same manner. 



FORMIC ACID. 



Formula HO + C 2 HO 3 =HO,FoO 3 . The relation of this 

 acid to wood spirit has already been explained. It was dis- 

 tinguished as a particular acid by Gehlen, who found it in red 

 ants (formica rufa) ; and was first formed artificially by 

 Dcebereiner, by distilling tartaric acid with sulphuric acid and 

 peroxide of manganese. All other vegetable substance when 

 oxidised in the same manner, or by distillation with nitric acid, 

 hyperiodic, iodic and hypermanganic acids, or with a mixture 

 of chromic and sulphuric acids, yield formic acid, carbonic acid 

 and occasionally some acetic acid. 



To obtain the protohyrlrate in a state of purity, formiate of 

 lead well pulverised contained in along glass tube is decomposed 

 by a current of dry sulphuretted hydrogen gas ; and the dis- 

 engaged formic acid afterwards distilled over by the application 

 of a gentle heat. This hydrate is a colourless liquid, slightly 

 fuming and possessing a pungent and peculiar odour. It 



