Pargas Inc. yesterday canceled an agreement to buy the liquefied petroleum (LP, or propane) gas distribution business of Dallas-based Sun Gas Liquids Enc., because the suburban Maryland firm has been unable to obtain satisfactory financing to complete the takeover.

As a result, acquisition-related expenses equal to 10 cents a share have been written off for the second-quarter. Overall net income fell to $459,000 (12 cents a share) in the April-June period from $1.18 million (31 cents) a year ago.

With the planned purchase of Sun Gas retail operations, Waldorf-based Pargas had expected to pick up about $100 million in annual revenues. Pargas President N. L. Langley said also that his firm would withdraw a proposed registration statement for a public offering of up to 1 million shares,which was related to the Sun Gas acquisition.

In the first six months of 1981, Pargas said profits rose to $6 million ($1.65) from $5.95 million ($1.63) after accounting for the acquisition expenses. Revenues rose to $135 million from $121 million. Langley said the volume of propane used for motor fuel rose, but there was reduced use of propane for other used in the recent quarter. Coupled with the Sun Gas costs, the LP business operated with a loss in the quarter. Coal profits continued to rise, he said.

Directors voted a regular quarterly dividend of 31 cents a share on common stock, payable Aug. 28 to owners of record Aug. 14.

Baltimore Gas & Electric Co. reported earnings rose to $74.9 million ($1.89 a share) in the first six months of 1981, compared with $57.2 million ($1.44) a year ago. Revenues increased to $698.6 million from $581 million. Electricity sales increased 4.3 percent in the recent six months from the same period in 1980.

Scope Inc. of Reston said second-quarter profits declined to $454,000 (37 cents a share) from $583,000 (48 cents), as revenues increased to $10.8 million from $18.1 million. Six-month earnings were off to $941,000 (77 cents) from $1.1 million (93 cents), and sales rose to $38.4 million from $35.3 million. Chairman William Schaub attributed the reduced profits to high interest rates that affected debt expenses as well as customer purchasing decisions. Scope manufactures electronic products.

United Services Life nad subsidiaries said second-quater sales rose 38 percent to $433 million as life policies in force totaled $7.92 billion, up $394 million in the last six months. Second-quarter operating earnings were $3.86 million (68 cents a share), compared with $3.65 million (65 cents) a year ago.

Although death benefits were $874,000 higher in the recent quarter than in the 1980 period, net income after securities transactions rose to $4.7 million (93 cents) from $3.7 million (66 cents). Assets were up more than 8 percent to $612.6 million. Directors also voted a quarterly dividend of 25 cents a share, payable Aug. 17 to owners of record Aug. 3.