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Marketable Securities (Schedule of investment income) (Details) - USD ($)
3 Months Ended 6 Months Ended
Jan. 31, 2022
Jan. 31, 2021
Jan. 31, 2022
Jan. 31, 2021
Investments, Debt and Equity Securities [Abstract]        
Interest income $ 1 $ 67 $ 1 $ 294
Dividend income 150,321 76,868 157,088 82,691
Gain on sale of marketable securities 48,213 48,213 83,176
Total $ 198,535 $ 76,935 $ 205,302 $ 166,161