Researches of inert gases in some mineral spring gases in Japan have been carried out with the conclusion that the primordial inert gases were contained in the ancient air which was enclosed in the internal parts of the earth, and in the long course of time the oxygen and nitrogen were gradually lost owing to their chemical activity leaving behind inert gases such as helium, neon, and argon. When the spring gases are produced largely underground and gush out of the earth they are accompanied generally by the primordial gases, that is to say, they come out upwards together with the inert gases.
The eicosatetraenoic acid separated from sardine oil was converted into the amyl ester, and the latter was subjected to ozonolysis. Among the products of ozonolysis were found: butyric acid, butyric aldehyde, succinic acid and amyl hydrogen succinate. The presence of succinic semi-aldehyde, succinic aldehyde and amyl ester of succinic semi-aldehyde was also indicated. Accordingly the constitution of the eicosatetraenoic acid is shown to be Δ4:5, 8:9, 12:13, 16:17-eicosatetraenoic acid as expressed by the following formula: CH_3·(CH_2)_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·COOH.
A concentrated fraction of eicosapentenoic acid containing an appreciable amount of eicosatetraenoic acid was converted into amyl ester and the latter was subjected to ozonolysis. Among the products of ozonolysis were found: succinic acid, amyl hydrogen succinate, amyl ester of succinic semi-aldehyde, carbon dioxide, acetic acid, acetaldehyde and a higher aldehyde (probably butyric aldehyde). The yield of these compounds and also the constitution of eicosatetraenoic acid (Δ4:5, 8:9, 12:13, 16:17) being taken into consideration, it was concluded that the eicosapentenoic acid had the following groups: =CH·CH2·CH=, =CH·(CH2)2·CH= and =CH·(CH2)2·COOH, of which it contained more than one of the group =CH·CH2·CH=. As the group at the CH3-side was left undetermined in these experiments, the constitution of the eicosapentenoic acid was not established with certainty. If, however, it is assumed that there are ethylenic linkings in 4:5-, 8:9- and 12:13-positions like in the eicosatetraenoic acid, the constitution must be Δ4:5, 8:9, 12:13, 15:6, 18:19-eicosapentenoic acid as expressed by the following formula: CH_3·CH=CH·CH_2·CH=CH·CH_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·COOH.