STUDY OF DRIERS AND THEIR EFFECT 27 



acetic, and other acids, while the acid radicals are converted by 

 oxygen into the anhydrides, from which they pass by further 

 oxidation into linoxyn. 



Auto-Oxidation of Oil. The theory of auto-oxidation of 

 linseed oil has been very ably treated by Blackler, whose experi- 

 ments indicated that during the drying process the slow absorp- 

 tion of oxygen was, at a critical period, followed by a rapid 

 absorption, which he attributes to the presence of peroxides. 

 The materials produced by this peroxide formation may act 

 as catalyzers and accelerate the formation of more peroxide. 

 Lead and manganese oxides may also be oxidized to peroxides 

 by the action of oxygen, and in this event might act as very 

 active catalyzing agents or carriers of oxygen. Bladder's 

 statement, that the presence of driers do not increase, but 

 have a tendency to decrease the initial velocity of oxygen 

 absorption, has been confirmed by these experiments, but it 

 has been noticed throughout the tests that the driers have an 

 accelerative action at a later period. 



Effect of Metals on Drying of Oils. Some most interesting 

 results were secured by dipping extremely fine copper gauze 

 into linseed oil, and then suspending the gauze in the air. The 

 adhesion of the oil to the copper caused the formation of films 

 between the network, and remarkable drying action was observed. 

 The copper or any superficial coating of copper oxide which 

 may have been present on the metal, undoubtedly affected the 

 result to some extent. It has been found that metallic lead is 

 even more efficient than copper in this respect, but this may be 

 due to the action of free acid in the linseed oil, forming lead 

 linoleates, products that greatly accelerate drying. Another 

 interesting experiment was made by immersing pieces of 

 gauze cloth in linseed oil. After the excess oil had been 

 removed, by pressing, the cloth was again weighed to deter- 

 mine the amount of oil used for the experiment. The increase 

 in oxygen absorption in this case was very rapid, and the result 

 obtained confirmed the results in the other experiments. 



In order -to secure a more evenly distributed state of the oil, 

 tests were conducted by saturating pieces of stiff blotting papers, 

 and, after exposure, weighing as usual. 



Influence of Light. The influence of light on the drying of 

 oils is unquestionably a potent one. The practical painter knows 



