580 CURRENT TOPICS. [J. I’. I.

growth and development, which may often prevail in the open field, such as a serious lack of soil moisture or plant food, it is conceivable that the tolerance of the plant for sulfur dioxide would be altered and this substance become a possible contributing agent to an un- flourishing condition.

R. H. 0.

Cleaning Gasoline Pipe Line.-(Oil and Gas Journal, Vol. 34, No. 34.) According to “Our Sun,” the house organ of the Sun Oil Co., trouble was not anticipated in 1930 by the Susquehanna Pipe Line Co. when their gasoline pipe line was laid, but by the middle of 1935 the capacity of the line was reduced from 15,000 to 12,000 bbls. per day. There are two branches of the line from Marcus Hook, Pa., one to Syracuse, N. Y., and the other to Cleveland, Ohio. The work of cleaning it began with taking up portions con- taining sharp bends and check valves and removing obstructions. Gasoline was removed from the section of the line to be cleaned by pumping through a water “plug.” The last phase of the cleaning operation employed two types of scrapers, a knife and brush type of scraper. Both were propelled or pushed through the line by the water pressure exerted by the pumps. The scrapers scrape the walls of the pipe free of scale. They travel through the pipe at a speed of 2 to 3 miles per hour. When a scraper becomes stuck in the pipe, a “bumper” scraper is sent through to aid the stuck scraper to move forward. The material removed by the scrapers was pushed ahead and finally discharged. Many foreign objects were removed including rocks, pieces of wood, tool parts, scraper parts, welding icicles, a IO ft. length of 2 X 4 lumber and a shorter piece of 2 X 4 entangled in a mass of burlap. The scale formed upon the inside of gasoline pipe lines is usually in the form of small pieces of iron oxide.

R. H. 0.

Bridge Railings Removable in Case of Floods.-J. \y. BERETTS. (Engineering News Record, Vol. I 16, No. 4.) Repair of flood dam- age to the international highway bridge over the Rio Grande be- tween Laredo, Texas, and Nuevo Laredo, Tamaulipas, Mexico has resulted in the installation of a railing that is easily detachable and thus may be removed on flood warnings, to eliminate an important obstruction to drift and current. Two past floods have overtopped this bridge and observations augmented by hydraulic calculations indicated that the old railing, of heavy concrete construction, offered as much as 50 per cent. of the total resistance of the structure con-