In a general way, enough of air is admitted by the cracks round the doors and windows; but if this be not the case, the chimney will smoke; and other plans, such as the placing of a plate of finely-perforated zinc in the upper part of the window, must be used.

" Take another modern instance: substitute for the tiled roofs of Rome, now so gray, tumbled, and picturesque with their myriad lichens, the cold, clean slate of New York, or the glittering zinc of Paris,should we gain or lose?

The dominant silver gleams in it barely sparkled, crawling with lack-lustre tones of dead zinc against the edges of the hard, tarnished shell.

The copper accumulates in their blood; the gold and silver are discovered in the texture of the animal-plants; the phosphorus is absorbed by the sponges; the lead and the zinc by species of algae.

Chemicals for producing acids are found in abundance; so also are copper and zinc for the plate.

A.The ordinary range of good yellow brass that files and turns well, is about 4-1/2 to 9 ounces of zinc to the pound of copper.