Federal Home Loan Mortgage Corp. yesterday said its third-quarter earnings climbed to $52 million ($3.14 per share).

Freddie Mac is a congressionally chartered corporation whose stock is owned by member savings institutions through common stock held for them by the 12 Federal Home Loan Banks

Its third-quarter earnings before taxes rose 35 percent to $97 million, compared with $72 milllion during the same period the previous year.

Freddie Mac became subject to taxation on Jan. 1, 1985.

Freddie Mac also said that its board of directors declared a third-quarter dividend on its preferred stock of 72 cents per share.

A dividend of $12 per share was declared on the corporation's common stock. Both dividends will be paid on Dec. 10 to stockholders of record on Nov. 26.

*Primark Corp., a McLean-based diversified energy and financial services holding company, reported a third-quarter loss of $5 million (26 cents per share), compared with a loss of $6.7 million (36 cents) for the same period in 1984.

The company said the loss was not unusual in the third quarter because of the seasonal nature of the company's gas utility business.

Earnings for the year ended Sept. 30 were $48.9 million ($2.55), compared with $55.7 million ($2.98) for the same period last year. The company attribued the decrease in earnings primarily to a 9.4 percent decline in utility retail sales largely because of weather.

*Flow General Inc., the McLean-based diversified scientific firm, reported a net loss of $507,000 (6 cents per share) on sales of $34.9 million for the first quarter of fiscal year 1986 ended Sept. 30. The company had a loss of $1.9 million (22 cents) on sales of $33 million for the same period last year. Robert J. Pasquale, vice president and chief financial officer, said the results for the first quarter were anticipated.

"They are consistent with our expectations of losses early in the fiscal year followed by profitable operation later in the year," he said. The full fiscal year 1986 is expected to be profitable, he said.

Flow General had reported a loss of $1.4 million for the fiscal year ended June 30, 1985, as well as a loss of $14.4 million for the fiscal year ended June 30, 1984.

Flow General, plagued in the past by criminal charges against a subsidiary, shareholder litigation and other difficulties, had experienced legal and financial problems in 1984, that had carried over into 1985. The company is still feeling the effects of having to rebuild a customer base in the first quarter of fiscal 1986, Pasquale said.

In August, 1984, the U.S. Attorney's Office for the Eastern District of Virginia, acting on behalf of the Food and Drug Administration, seized millions of dollars' worth of tissue cultures and other medical items at the company and shut down its manufacturing facilities following complaints of adultered products and other problems. The firm later reached an agreement with the FDA allowing the facility to resume production.

"There is no hold-over from that in 1986, except that we are trying to rebuild our customer base from the lost customers as a result of that [FDA] action," said Pasquale. The losses in the first quarter of the year are primarily attributable to international operations that traditionally break even in the first quarter because of extended summer vacation periods, he said.