s ▁and ▁it ▁is ▁considered ▁as ▁a ▁prede cess or ▁of ▁the ▁gas ▁comb ust ion ▁ret ort ▁and ▁the ▁Par aho ▁processes . ▁ ▁It ▁was ▁invent ed ▁and ▁pat ented ▁by ▁Roy ▁C . ▁D und as ▁and ▁Raymond ▁T . ▁How es ▁in ▁ 1 9 2 3 . ▁The ▁process ▁was ▁improved ▁by ▁David ▁Davis ▁and ▁George ▁W ight man ▁Wal lace , ▁a ▁consult ing ▁engineer ▁of ▁the ▁N T U ▁Company . ▁ ▁In ▁ 1 9 2 5 , ▁the ▁N T U ▁Company ▁built ▁a ▁test ▁plant ▁at ▁Sh erman ▁C ut ▁near ▁Cas mal ia , ▁California . ▁▁▁ ▁In ▁ 1 9 2 5 – 1 9 2 9 , ▁the ▁process ▁was ▁tested ▁by ▁the ▁United ▁States ▁Bureau ▁of ▁M ines ▁in ▁the ▁O il ▁Sh ale ▁Ex periment ▁Station ▁at ▁An vil ▁Point ▁in ▁R if le , ▁Colorado . ▁ ▁Ret ort ing ▁was ▁carried ▁out ▁from ▁ 1 7 ▁January ▁to ▁ 2 8 ▁June ▁ 1 9 2 7 . ▁The ▁plant ▁was ▁dis m ant led ▁when ▁work ▁was ▁terminated ▁in ▁June ▁ 1 9 2 9 . ▁ ▁One ▁of ▁the ▁leading ▁techn ologist ▁involved ▁in ▁this ▁stage ▁was ▁Lewis ▁Cass ▁K arr ick , ▁an ▁invent or ▁of ▁the ▁K arr ick ▁process . ▁ ▁In ▁ 1 9 4 6 – 1 9 5 1 , ▁two ▁pilot ▁plants ▁with ▁nom inal ▁capac ities ▁of ▁ 4 0   tons ▁of ▁raw ▁oil ▁sh