Comment is not necessary to show the bad results of using gas tar on heating pipes. So many instances have been recorded in horticultural works, of its injurious effects on plants, that no reader will fall into the error of using it.

But I have experienced the ill effects of it in another way which plainly demonstrates its detrimental properties. Three years ago I had a greenhouse built; and in a novel position. It was on the top of a substantial shed; but circumstances were such that no other place was available. This shed was on the lower level of eighteen feet from where I had to put it; its roof coming to the level of my other houses, with which I wanted to connect it. This roof was what is called a flat one, covered with galvanized iron. On this it was built. Knowing that it would be difficult to heat with the space cold below, I had first a good coating of tar and sand put over the roof of the shed, so as to make it perfectly close, and then six inches of well-packed concrete. Knowing the bad results arising from tar, I was extremely careful that every portion should be close, but as soon as the heating commenced its smell became strong, doing considerable damage. I was in a dilemma, as bad almost as if the pipes had been covered with tar. To tear up the floor at that season of the year, with the house full of plants, and no other place to put them in, the other houses being taxed already to the fullest extent, was out of the the question. The floor seemed so close that one would think no gas could escape.

However, I gave it another cover of cement, made as thin as could be, so that it would run into any cracks that might exist. This gave me partial relief, so that the bad effects were much reduced, and in the end disappeared entirely. I send you this statement as a warning to all that may construct greenhouses, never to use gas tar in any connection whatever with them. Supt. Govt. Grounds, Ottawa, Can.