if you do not get that, you have a poor paint. Further, the quality of paint depends quite as much upon its physical as it does upon its chemical properties.

Mechanical Tests.—By this is meant tests made by a skilful painter. No one can determine the working qualities of paint as well as the man whose eye and hand and arm are trained through practice. The importance of the proper application of paint receives less attention than it deserves; e.g., air bubbles may be worked out of paint by means of thorough brushing with good tools, and then again a poor painter may use 25 per cent. more material upon a given surface than a good painter will use, and get poorer results with it. Engineers and architects should demand the employment of competent artisans to do their painting, for results  are  often   more  dependent  upon