SCIENCE IN THE INDUSTRIAL WORLD 



which can be produced in great quantities and at a cost 

 that is a mere fraction of that of any of the others. 



Linseed oil is the product of the seed of the flax 

 plant, Linum usitatissimum, which is grown abundantly 

 in every grain-raising region of the world outside the 

 tropics. It is a little seed, flat oval in shape, lustrous, 

 and of a pale-brown color. The oil is obtained from 

 the seed by a process of pressing, after the seed has 

 been subjected to a series of preparatory processes. 



As a vehicle for pigments it is marketed in two forms, 

 known respectively as "raw" and "boiled" oil. The 

 raw linseed oil is the product obtained from the seed 

 by pressure, without further treatment or at most a 

 process of clarifying and refining and represents 

 the oil practically in a state of nature as it exists in the 

 seed. The boiled oil, as the name suggests, is the natural 

 oil which has been heated above the boiling point (about 

 500 F.) and to which is added a small quantity of some 

 substance known as a "drier." The boiling and the 

 addition of the drier change the chemical composition of 

 the oil slightly, and give it somewhat different proper- 

 ties from the raw oil mostly in the matter of increas- 

 ing its rapidity in drying. For this reason it is a favorite 

 vehicle for many kinds of painting where a hard, tough, 

 lustrous coat that dries quickly, is desired. This coat 

 is somewhat more prone to crack than the one formed 

 by raw linseed oil, but this tendency may be corrected 

 by adding a little raw oil to the mixture, the compound 

 forming the ideal vehicle for most commercial painting. 



The quantity of drier added to the boiling oil is very 

 small, usually four or five pounds to the ton of oil. 



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