TESTS AT ATLANTIC CITY AND PITTSBURG 177 



straight white leads, the original white leads used in the previous 

 tests were included, and other brands were added. Each formula 

 was painted out in white, yellow, and gray, upon panels of white 

 pine wood arranged in sequence upon the fence, and properly 

 identified. The customary opacity test, in the form of a small 

 black square, was stencilled over the priming coat of each panel, 

 as in the former tests. The composition of the vehicle in all 

 the new tests was standard, using pure linseed oil with a small 

 percentage of turpentine drier. The tints used in each formula 

 were secured at the time of application by the use of standard 

 colors, lampblack, and medium chrome yellow, using an approxi- 

 mate amount for each formula. 



An inspection of these new tests was made during June, 1910, 

 and the results of the inspection are shown on pages 174 to 177. 

 The results of the inspection prove that it is unsafe to use litho- 

 pone in a paint containing white lead of any type, early darkening 

 and failure being shown in every case where such a combination 

 existed. The formulas in the new test, which were properly 

 balanced and which had a low percentage of lithopone combined 

 with zinc oxide and whiting, presented in some cases very good 

 surfaces. A rough, sandy surface, however, was shown where 

 lithopone was used in any great quantity. 



