=Panel Sections for Laboratory Test.= In order to make a laboratory study of the painted panels on the Atlantic City and Pittsburg fences, it was thought advisable to remove small sections from representative areas and transfer them to the laboratory for such work. The fences were visited by the official inspection committees soon after the first annual inspection, and the panels were carefully looked over. Upon each was marked out a representative portion, care being exercised to select areas where previous inspections had not disturbed the surface of the film in any manner. The inspectors then placed the number of the panel upon the areas which had been marked off, as well as their initials. The marked sections were sawed out, wrapped in tissue paper, and then transferred to the laboratory where they were placed upon models of the respective fences from which they had been removed. The illustration shows the model test fences set up together. It is very apparent that the Pittsburg panels are much the darker in color, due to the soot, and in some cases lead sulphide formed upon their surfaces. This difference was undoubtedly due to the atmospheric conditions prevailing where the tests were made. One would be led to suppose that a paint film exposed to an atmosphere such as is found in Pittsburg would show deterioration more rapidly than one exposed in Atlantic City. In all the tests and experiments, however, the Atlantic City panels appeared broken down to a much greater extent; though it is true that the Pittsburg panels had darkened considerably and presented a rather mottled appearance. The deposit of soot on the Pittsburg panel seemed to act as a preservative coating for the film beneath, and prevented marked disintegration. [Illustration: Sections of Atlantic City and Pittsburg Fences Arranged for Laboratory Examination] [Illustration: Sections of Atlantic City and Pittsburg Fences] [Illustration: Upper set of tests made on Panels from Atlantic City Fence Lower set of tests made on Panels from Pittsburg Fence Figures at left indicate Formula Number Figures at right indicate Degree of Chalking] [Illustration: Color Standard used in Comparison of Panel Section] =Chalking Test.= Small strips of black felt, about one inch square, were firmly attached to a block of wood, and by a clamp having the same pressure in each case, the wood with its surface of black felt was fixed to the panel. This apparatus, which resembles a blackboard eraser, is firmly drawn across the panel in one direction for a certain definite distance, during which time it gathers all the chalked surface presented by the painted wood. Upon detaching the apparatus from the panel it is observed that the black cloth becomes whitened to an extent proportionate to the chalking that has taken place on the given area.