Cash Flow Information (Schedule of supplemental disclosure) (Details) - USD ($)	3 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Cash Flow Information
Interest paid, net of capitalized interest of $7,762 (2021) and $17,132 (2020)	$ 81,527	$ 67,839
Income taxes paid (refunded)
Capitalized interest	$ 7,762	$ 17,132