They are both probably diminished in immense quantities by uniting with the inflammable air, which arises from the mud of rivers and lakes at some seasons, when the atmosphere is light: the oxygene of the air producing water, and the azote producing volatile alcali by their combinations with this inflammable air. At other seasons of the year these principles may again change their combinations, and the atmospheric air be reproduced. Mr. Lavoisier found that one pound of charcoal in burning consumed two pounds nine ounces of vital air, or oxygene. The consumption of vital air in the process of making red lead may readily be reduced to calculation; a small barrel contains about twelve hundred weight of this commodity, 1200 pounds of lead by calcination absorb about 144 pounds of vital air; now as a cubic foot of water weighs 1000 averdupois ounces, and as vital air is above 800 times lighter than water, it follows that every barrel of red lead contains nearly 2000 cubic feet of vital air. If this can be performed in miniature in a small oven, what may not be done in the immense elaboratories of nature! These great elaboratories of nature include almost all her fossil as well as her animal and vegetable productions. Dr. Priestley obtained air of greater or less purity, both vital and azotic, from almost all the fossil substances he subjected to experiment. Four ounce-weight of lava from Iceland heated in an earthen retort yielded twenty ounce-measures of air. 4 ounce-weight of lava gave 20 ounce measures of air. 7 ............... basaltes .... 104 ...................... 2 ............... toadstone .... 40 ...................... 11/2 ............... granite .... 20 ...................... 1 ............... elvain .... 30 ...................... 7 ............... gypsum .... 230 ...................... 4 ............... blue slate .... 230 ...................... 4 ............... clay .... 20 ...................... 4 ............... limestone-spar .... 830 ...................... 5 ............... limestone .... 1160 ...................... 3 ............... chalk .... 630 ...................... 31/2 ............... white iron-ore .... 560 ...................... 4 ............... dark iron-ore .... 410 ...................... 1/2 ............... molybdena .... 25 ...................... 1/2 ............... stream tin .... 20 ...................... 2 ............... steatites .... 40 ...................... 2 ............... barytes .... 26 ...................... 2 ............... black wad .... 80 ...................... 4 ............... sand stone .... 75 ...................... 3 ............... coal .... 700 ......................