General Electric Co., one of the country's largest industrial firms and a major producer of consumer goods, reported a substantial increase in profits yesterday for the second quarter.

Although GE's earnings statements had little indication of economic slowdown, the country's largest food chain - Safeway Stores Inc. - reported separately that profit growth eroded sharply while sales increased only modestly in the three months ended June 16. And Safeway profits were down for the first half of 1979.

CBS Inc., a leading communications firm, meanwhile listed record profits for the second quarter, which partly reflected lower federal taxes. Earnings of CBS for the first half of 1979 were off from last year, because of higher expenses at the CBS television network, among other factors.

GE's second-quarter profits rose to $382 million (1.69 a share) from $319 million ($1.40) in the same period a year ago. Sales jumped to $5.14 billion from 4.96 billion.

For the first six months, profits rose to $686 million ($3.02 a share) compared with $567 million ($2.49) and sales were up to 10.72 billion from $9.41 billion.

Chairman Reginald Jones cautioned that the outlook for remaining months this year "is unsettled with GE economists seeing a slowdown in the U.S. economy and continued high rates of inflation."

He said recent strong profit gains by GE, the ninth-largest U.S. industrial firm, resulted from cost controls and the sales increases. About two-thirds of the higher sales were real shipment gains and price increases accounted for the balance, Jones noted.

Safeway Stores, a California firm that is one of the Washington area's two largest food retailers, said second-quarter profits rose just 2.8 percent to $42.5 million ($1.63 a share) compared with $41.2 million ($1.58) a year ago. Sales were up 7 percent to $3.13 billion in a period when consumer prices rose at an annual rate of more than 10 percent.

For the first six months, Safeway earned $65.6 million ($2.51 a share), off 1.3 percent from 6.5 million ($2.55) last year. Sales were up 7 1/2 percent to $6.2 billion.

Also, Safeway noted that six-month results included a loss on translation of foreign currency statements of $386,000 compared with a loss of $2.4 million in the 1978 period - indicating an even greater erosion of real profits in 1979.

News Services also reported the following:

CBS Inc. said second-quarter profits were 11 percent above those of a year earlier despite rising television network costs.Profits were $65.8 million ($2.37 a share) compared with $59.3 million 2.14) a year ago. Revenues rose from $751.4 million to $913.8 million.

For the first half of 1979. CBS profits fell to $83.6 million ($3.01 a share) from last year's first-half earnings of $93.1 ($3.36). Revenues rose to $1.7 billion from $1.5 billion.

While second-quarter radio and TV revenues were 14 percent above last year's level, "costs increased at a rate greater than revenues in the television network," primarily due to rising expenses for news and prime-time entertainment programming, CBS said.

CBS said profits fell in its division which manufactures phonograph records for other companies, and in its domestic record distribution division.

International Paper Co., the world's largest producer of paperboard, paper, and pulp products, reported a 20.9 percent increase in earnings for the second quarter.

Earnings from continuing operations were $80.9 million ($1.69 a share) compared with $66.9 million ($1.41) in the year-ago quarter.

The film, which is North America's largest private owner of forest lands, said orders were strong for most pulp and packaging products, with production of lumber and plywood higher than the second quarter last year. Earnings for the first half of 1979 were $258.5 million ($5.41 a share) vs. $121.7 million ($2.57).

Raytheon Co., like GE one of the nation's largest diversified makers of electrical equipment, reported higher second-quarter and first-half sales and earnings. Second-quarter profits were $51.1 million ($1.63 a share) compared with $39 million ($1.26) last year. Sales for the Lexington, Mass.-based firm rose to $960.6 million in the quarter from $834.4 million a year ago.

In the first half, profits were $94 million ($3.01 a share) compared with $71.6 million ($2.31) and sales were $1.86 billion, up from $1.6 billion a year ago.

International computer firms Control Data Corp. and NCR Corp. reported second quarter earnings from continuing operations considerably improved from year-ago levels.

Control Data, engaged in computer services, systems, related products businesses and financial and insurance services, reported net earnings of $37.6 million ($2.18 a share) in the quarter, an increase of 68 percent from the 1978 quarter. In last year's quarter, earnings totaled $25.5 million ($1.48). Revenues for the latest period were $772 million, compared with $666 million a year ago.

NCR Corp., which produces business and computed equipment, reported second quarter net income from continuing operations of $58.9 million, up 48 percent from $39.9 million a year ago. Earnings per share in the latest quarter were $2.23, up 58 percent from $1.41 a year earlier.

Two large bank firms in New York - J. P. Morgan and Marine Midland Banks - also posted sharp earnings gains, reflecting higher interest rates.

Morgan, holding company for Morgan Guaranty Trust and the nation's fifth-largest bank company, earned $70 million ($1.72 a share) in the recent quarter compared with $61 million ($1.51) last year, not counting securities transactions.

Marine Midland, based in Buffalo, posted a 90 percent gain in second-quarter operating profits to $10.5 million (84 cents a share) from $5.5 million (44 cents).