Kindly allow me a few lines in reply to your correspondents, A.M.A. and Adam Kenton, with respect to the building of their frames, the former with gas-tar, the latter with gas-lime. For my own part, I do not see any analogy between the two cases, owing to the very great difference in the composition of the materials used. Gas-tar contains a large quantity of naphtha, and it is doubtless this ingredient which makes it dangerous to the life of plants, especially when the frame is warmed by artificial heat, and kept closed. We have all experienced the disagreable smell rising from walks made of ashes and gas-tar when the heat of the summer affects them, while in cold weather no such smell is emitted. Gas-lime is composed principally of lime, in which is absorbed sulphuretted hydrogen and carbonic acid gases; and this compound being in a moist state, a certain quantity of ammonia is mechanically held by it. This latter compound is a great fertiliser, and the agreeable softness of rain-water is due to the presence of this alkali.

The " pungency " of gas-lime is doubtless owing to the presence of this gas; for when newly prepared and carefully applied it is found very destructive to wire-worms, slugs, earth-worms, etc., its caustic properties dissolving, so to speak, their tender skin.

On the application of a gentle heat, the ammonia is drawn away from the gas-lime, so that there is left the sulphuret and carbonate of lime, neither of which, when used in the composition of mortar, could do any harm. Gas-lime, when laid up with loam for a few months, makes a first-rate dressing for lawns, etc, imparting to them a rich green appearance. A few years ago this mixture was applied to a cricket-ground in my neighbourhood, and throughout the season there was a grand herbage on it, the sheep being particularly fond of the feed so produced. An Amateur Chemist and Gardener.