1915] on Science and Industrial Problems 813 



and the liquid g-lyceride, triolein, is converted into the solid glyceride 

 tristearin : — 



CgH-OOC.Ci^Hgg + SH. = C3H.-OOC.C 'h',' 



■^OOC.Ci,H33 " ' '^OOCCilHg;; 



Chemical saturation as such is not, however, of particular interest 

 to the manufacturer, who looks rather to the point at which the 

 addition of hydrogen will convert an oil into a workable solid fat. 



Though by weight the amount of hydrogen required for this pro- 

 cess is not great, by volume it assumes enormous proportions. One 

 ton of oleic acid requires roughly 79,000 litres or 2800 cub. ft., and 

 one ton of triolein requires 75,900 litres or 2680 cub. ft. of hydrogen. 



The question of producing hydrogen in sufficient quantity for 

 carrying out this process is an interesting one in itself, but it must 

 suffice to say that the question has tested the combined skill of 

 chemists, physicists, physical chemists, and engineers, with the result 

 that not only is the fat-hardening industry established, but such 

 things as airships filled with hydrogen are known, and the latest of 

 all chemical industries, namely, the synthetic production of ammonia 

 gas from nitrogen and hydrogen, has sprung into existence. 



It is not easy to obtain any accurate idea of the amount of oils 

 which are thus treated annually, but it may be mentioned that 

 hydrogen is being produced by the Linde Company's method (Zeit. 

 angew. Chem., 1913, xxvi. (3) 814) in sufficient amount to harden 

 100,000 tons of fat annually. There is, further, a factory in Norway 

 capable of producing 4500 cub. metres of hydrogen by an electrolytic 

 method, and of hardening 150 tons of whale oil every 24 hours 

 (Offerdahl, see later). 



The question naturally arises, Why has the hardening of fats 

 assumed such large proportions ? The answer being that so much 

 of the natural supply of hard fats is now employed in the making of 

 margarine and other foodstuffs, that the amount of such fats avail- 

 able for soap-boiling has been considerably encroached upon, and 

 hence it has become necessary to find other sources of hard fats for 

 the latter purpose. 



One of the principal oils now submitted to the process of 

 hardening is whale oil, of which the world's supply in 1912 amounted 

 to 1,200,000 barrels, more than half of w^hich was obtained from 

 Norway (Offerdahl, Ber. deutsch. Pharm. Ces., 1913, xxiii. 558). 

 Ten or fifteen ;years ago only small amounts of whale oil were used 

 in the tanning industry or for lubricating, its taste and smell pro- 

 hibiting its employment for other purposes. More recently larger 

 quantities have been worked up for the isolation of glycerol, but the 

 oil is now almost entirely hardened to a substance melting between 

 40° and 50°, which possesses neither taste nor smell. 



The idea of hardening fats is not a new one, and many attempts 



