Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Net income	$ 2,301,504	$ 2,452,524
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	84,210	95,956
Net (gain) loss on marketable securities	(344,043)	153,406
Deferred income taxes	(45,072)	(32,215)
Increase (decrease) in operating assets:
Accounts receivable	139,312	(246,534)
Inventories	181,360	(159,846)
Prepaid expenses and other current assets	(70,452)	(24,695)
Prepaid income taxes	169,207	0
(Decrease) increase in operating liabilities:
Accounts payable	(96,345)	119,052
Accrued expenses	323,131	386,717
Income taxes payable	0	(40,849)
Net cash provided by operating activities	2,642,812	2,716,353
Cash flows from investing activities:
Acquisition of property, plant and equipment	(31,655)	(40,552)
Proceeds from sale of marketable securities	9,359,971	4,097,370
Purchase of marketable securities	(9,085,612)	(1,350,509)
Net cash provided by investing activities	242,704	2,706,309
Cash flows from financing activities:
Dividends paid	(2,524,946)	(2,291,294)
Net cash used in financing activities	(2,524,946)	(2,291,294)
Net increase in cash and cash equivalents	360,570	3,131,368
Cash and cash equivalents at beginning of period	550,135	724,721
Cash and cash equivalents at end of period	910,705	3,856,089
Non-cash investing activities: cost of equipment traded in (net)		39,837
Supplemental disclosure of cash flow information
Taxes paid	475,000	725,000
Supplemental disclosure of non-cash dividends payable	$ 1,930	$ 5,867