The Senate devoted 38 days to the Panama Canal treaties and has about 120 working days left this year to settle the other problems of the nation and the world. That assumes adjournment soon after Oct. 1 to allow time for campaigning.

House and Senate Democratic leaders are working up their agenda for the rest of the session and will meet next week to synchronize their operations. "They can't sit around twiddling their thumbs, but there is time enough to address issues that need to be addressed," said a Senate leadership aide.

It already is obvious that some of the time-consuming issues will be left for the next Congress. They include welfare revision, national health insurance and results of the strategic arms limitation talks (SALT).

The bill that could tie the Senate up for the longest time is the labor revision legislation the Housae has passed. Opponents are geared up for a long postcloture filibuster that could go on for weeks. Labor hasn't got much from this Congress and Senate leaders want to pass the bill but it could be yanked if the fight appears endless.

The business Congress must take up includes the long list of annual bills authorizing department budgets (such as Energy, Justice and military procurement), extension of programs that expire (such as aid to elementary and secondary education and public service jobs) plus more than a dozen appropriation bills providing the money for them.

Then there is the special legislation the president or Congress wants. First, is President Carter's tax cut-tax revision bill, which probably will serve as a vehicle for all kinds of fights. There will be efforts to roll back Social Security taxes and give tax credit to help pay college tuition.

The energy bill, one year old today, is still bogged down in a House-Senate conference. Members insist they finally will resolve their differences on natural gas pricing and take a bill back to the House and Senate, where more long fights could ensue. If the conferees do settle natural gas pricing, they face another long fight over the tax provisions.

Congress faces at least three foreign policy fights in the proposed sale of military aircraft to Egypt, Saudi Arabia and Israel (which the president will send to Congress next week), resumption of aid to Turkey and truning over military materiel to South Korea.

Other bills awaiting congressional action would update rules for drilling for oil and gas on the outer continental shelf, specify use of the land mass of Alaska, try to hold down hospital costs, reorganize the Civil Service, provide a more modest increase in farm price support levels than the bill killed in the House last week and revise the criminal code.