Q. Please explain the best method of making rust-joints. Are they as good as lead joints?

A. They are sometimes used for joints in iron pipe, but are not so certain to be tight as well-calked lead. The best method of making such joints is to mix iron filings and a little sal-ammoniac, wet, and ram them into a joint over a gasket before it has been mixed long enough to rust the filings. The process of rusting expands the iron, and may, perhaps, make the joint tight if carefully mixed and filled - not otherwise.