Q. Please inform me of the best mixture of paint to use on lead-lining of tanks. The lining is full of pin-holes, and has only been in use a year. It is lined with 6-pound sheet-lead. The tank is used for supplying water-closets.

A. We know of nothing better than what is sold as " black varnish." There are two different articles sold under this name. One has a basis of coal-tar, and when used may be diluted with naphtha; the other has a basis of natural asphalt, and may be diluted with spirits of turpentine. We do not know that one is more durable than the other. The tank should be perfectly dry when the paint is applied. We do not know how long, at the longest, such a coating will last, but it can be renewed at a trifling expense whenever the tank is cleaned.