PHYSICAL LABORATORY PAINT TESTS 79 



mined. The cubic contents of the pressure tube and side-arm 

 become increased, owing to the cup-like shape the paint film 

 takes on. By subtracting the amount of mercury indicated by 

 the piston in the pressure tube from the amount of mercury 

 delivered from the burette, the amount contained in the dis- 

 tended paint film is obtained, which serves as a measure of elas- 



Gardner-de Horvath film testing appa- 

 ratus 



ticity. The temperature is a most important point to consider 

 in running daily tests upon the filmometer. The tests made by 

 the writer were conducted at 70 degrees Fahrenheit throughout. 

 Gardner-de Horvath Filmometer. Another type of filmom- 

 eter which gives very concordant results was recently devised 

 by the writer and de Horvath. This apparatus is shown above. 



