160 C. W. DAELEY. 



desirable to allow a wide margin in such structures as this for 

 " life '' as attention in the way of cleaning and painting may at 

 some period be neglected, and then the strength will be de- 

 teriorated. 



A great deal of consideration has been given to this subject 

 before determining the best method of painting or coating the 

 interior of these steel tanks to prevent them from corrosion. 



In the first instance the system of coating them with hot 

 Stockholm tar and cement was specified, this has been found to 

 answer admirably in iron ships to protect the skin from the 

 action of bilge water. Many large ship-builders on the Clyde 

 and Tyne use almost nothing else. However, before applying the 

 coating to the tanks, it was laid on plates and exposed in the 

 S.W. S. Canal and found an absolute failure, the tar becoming 

 quite soft and washing off. Numerous other paints and patent 

 compositions were similarly tested, and the result was to shew 

 that not one of the substances tried approached red lead as a 

 protective coating. The inside of the tanks were therefore well 

 cleaned and given two coats of red lead and oil paint, the first 

 coat being laid on thin, and over the red lead were laid two coats 

 of zinc white paint, the second coat being mixed with a little 

 varnish to harden it. The outside of the tanks were given two 

 coats of oxide of iron paint, and finished with two coats of white 

 lead and oil paint suitably tinted. 



When conducting the tests of various coating substances 

 already referred to numerous mixtures of asphalt paint, and 

 asphalt dissolved in spirit, were tried with only partial success, 

 indeed any substance which is mixed with spirits or other volatile 

 liquid is questionable, as the liquid when evaporating leaves 

 minute passages or cells through the pigment, through which the 

 moisture gains access to the plate, and corrosion commences. 



A plan of rolling out sheets of pure asphalt aboufc one-sixteenth 

 of an inch thick, and about sixteen inches square, was invented 

 and patented by Mr. T. Pridham, these sheets are applied to the 



