106 
Proceedings of the Royal Irish Academy. 
1. On the Production of Acetic Acid from the Destructive Distillation of 
Pesin. 
On submitting resin to destructive distillation, amongst other pro- 
ducts is an aqueous solution possessing strongly acid properties and a 
very powerful empyreumatic odour. A specimen of this fluid was 
neutralized with carbonate of sodium, evaporated to dryness, and 
fused to get rid of colouring matter and volatile impurities. The 
residue was then dissolved and crystallized twice, by which means 
beautifully clear and apparently pure crystals were obtained. This 
sodium salt gave, in solution, a red coloration with ferric chloride, 
and a white crystalline precipitate with nitrate of silver ; when 
decomposed in the presence of alcohol by sulphuric acid it gave the 
well known odour of acetate of ethyl. 
The precipitate got on adding nitrate of silver, when purified by 
washing and re-solution, gave on ignition -913 gramme of silver from 
1*413 gramme of the silver salt used. This acid is therefore acetic* 
Ag. 1-413 
Theory c H Ag 0 ""'^^^^ Practice -913 
It is rather surprising to see acetic acid produced in appreciable 
quantities from a substance so comparatively poor in oxygen — parti- 
cularly as oxygenated oils also constitute a comparatively large per- 
centage of the products of destructive distillation. The relative amounts 
of oxygen in colophony and in an acid-yielding substance differ consi- 
derably — e. g. 
Colophony C20 II30 O2 Cellulose Ce Hio O5 
Oxygen per cent. 10-6 49*4 
The amount of water which comes over in the destructive distil- 
lation of resin is not large, but what there is, is very rich in acetic 
acid ; 85 parts of resin give about 74 of liquid products — about two 
parts of which constitute the aqueous portion. This latter has a spe- 
cific gravity of 1-018 at 15° C, and estimated with a volumetric solution 
of soda it was found to contain 11-8 per cent, of the hydrated acid. 
Perfectly clear and transparent resin, when powdered and dried over 
sulphuric acid, lost '43 per cent. — 1*389 gramme, after drying, 
weighing 1*383, whilst opaque pieces lost much more. It is therefore 
probable that a portion of the aqueous fluid was due to moisture pre- 
existing in the resin. 
2. On the Production of Ozotie by Pesin Oils. 
When the light oils of resin are submitted to the combined action of 
atmospheric oxygen and light, all the phenomena indicative of the 
* Dr. Thomas Anderson observed that the most volatile fraction of the resin oils 
contained a trace of what appeared to be acetic acid. The above note will account for 
its presence there. 
