This section is from the book "The Gardener's Monthly And Horticulturist V18", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
You will be doing many a poor fellow a great kindness if you will again warn, and keep warning, against the common and fatal mistake of painting hot-water pipes in greenhouses with gas tar.
I have done so several times in the Monthly, but as you know that we are getting scores of new and inexperienced men every year into the business who keep falling into this error, it is well to keep on. Already two of my customers report this season that they have so blundered, and the effect has been ruinous in each case. As you are aware, if the mischief has been done, there is no other remedy but taking the pipes out and burning them thoroughly until the gas is entirely expelled from the iron.