Most coal contains sulphur, and when burning the sulphurous flames injure plants. In like manner there is some sulphur in illuminating gas, and it is given off during burning. Much of what is supposed to be the injury from dry air in rooms and greenhouses comes from sulphurous fumes. We have only to note how plants grow in the dry summer air when they get food and moisture enough at the roots, to understand that a dry atmosphere is not unfavorable to good plant growth. Many persons are disgusted with plant growing from a prevalent belief that the atmosphere has to be as damp as a Brazilian swamp. In dry air, however, red spider, the most destructive of plant enemies, is apt to flourish. It is so small that one is not apt to see it until great damage is done. They are no larger than needle points, and are generally found on the under surface of the leaf. They are called "spiders" because they make webs like a true "arachnoid," as the learned call those insects which belong to the spider tribe. If one has but a few plants this troublesome insect may be easily kept down by continual examination, and crushing with finger and thumb. There are, however, some plants which have leaves that will not admit of this sort of handling.

It is, therefore, a good plan to place the plants on their sides occasionally and syringe them with water warmed to about 130°. Soapy and other washes often recommended are also great aids in this washing process.

In watering plants much judgment is required, as plants suffer much more from over-watering than from any other cause. No one can teach exactly how to water plants. The knowledge must come from experience. The practiced eye detects by the color of the earth whether it needs water or not. Whatever may be the color of the earth employed in potting plants it is always paler when dry than when wet. Again, the practiced plant-grower learns to tell by the weight alone. By lifting the pot the weight tells if too dry. If too wet it will be much heavier than it ought to be.

Basket plants often suffer from too much or too little water. If from too little, the leaves curl or fall, and the plants have a dried-up appearance. If too much, they get yellow and drop off. As a rule, a basket in a warm room, should be taken down once a week, and soaked in a bucket of water, then drained and hung up again. Every day during the rest of the week a little water may be given the plants, and something put under to catch the drip. Some baskets have no provision for the escape of moisture. These are dangerous. Still some people manage to watch closely, and do well with them. Fern cases do best when given a little sun; for, though ferns are supposed to grow naturally in shady spots, it is because there is generally a more humid atmosphere there. If they can get this moisture, they rather like light.