THE ANALYST. 171 ON THE PROPORTION OF FREE TATTY ACID IN CERTAIN OILS OF COMMERCE. BY L. ARUHBUTT, 3.C.S. 1. Oliva Oil.-During the past few years I have frequently examined samples taken from large brillrs of olive oil intended for lubricating. The proportion of free fatty acid (calculated as oleic acid) in 89 samples which proved to be genuine, ia given in the fol- lowing table :- Tree O b i ~ Acid per c a d . Origin of oil. No. of Barnplea. Highest. Lowest. Average. hlalaga .. 12 .. 25'1 .. 2.3 .. 8.1 deville .. 7 .. 10.0 .. 2'5 .. 5.3 Gallipoli ,. 3 ,. 15.0 .. 8.2 .. 129 Gioja ,. 2 .. l"0.4 .. 10.0 .. 109 Measina .. 5 .. 11.3 .. 8.2 ., 9.0 Unknown ., 60 .. 24*5 .. 2.2 .. 8.0 These results show that olive oil is liable to contain very considerable proportions of free fatty acid, which very much detracts from its value as a lubricant.1 have also found it;, on'thia account, very unsuitable for burning in lamps, tho free acid (if exceed- ing about 3 to 5 per cent,) having a very serious charring action upon tbe wick. 2. . R q o OF Colm OiZ.--Tfiis oil always contains a certain proportion of free fatty acid, but a far smaller and less variable proportion than olive oil. 44 sampleB of genuine refined rape oil for lubricating and burning, contained the following proportions of free acid, calculated as oleh :- Nighest; .. .b .. .. 5-5 percent, Lowest ,, .. .. *. 1.7 Averago ., .. .. 3.0 ,,172 THE ANALYST. 3. Palm OiL-This oil is liable to contain very large proportions of free fatty acid, as the following nine samples show :- Brand. Free Fatty Acid, caloulated as Palmitic. 1. Salt-pond . . . . . . . . . . 78-9 per cent. 2. Unknown . . . . . . . . . . 72.0 ,, 3. Brass . . . . . . . . . . 53-2 ), 6. Unknown . . . . . . . . . . 35*3 ,, 6. Half Jack . . . . . . . . . . 24-4 ,, 7. Bonny . . . . . . . . . . . . 21.5 .. S. 'uiilmown . . . . . . . . . . 13.3 ,, 9. Lagos .. . . . . . . . . . . 11.9 ,, 4. ~ e w CalaiAr . . . . . . . . . . 52*2 ,, Free palmitic acid has a very corrosive action upon steel. A strip of bright steel immersed in palm oil containing free acid, will soon become discoloured, and will he- quently be .found to be deeply pitted in places, if left some time in the oil. The action is very irregular, and I have not always found the most acid oil @ve the womt results.