The APPENDIX.

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tained in the bladders of our seaweed, ? of a measureworse than common air.

That the comparative difference of these three may moreeasily and immediately be feen, I will set them down inthe manner I generally do in my experiments.—On mygraduated tube, the interval between dephlogisticated airand perfectly noxious air, is divided into forty-two equalparts, and thus forms a scale of forty-two degrees.—Onthis scale, o is fixed at the division which marks goodcommon air.—From o up to dephlogisticated air, takestwenty two of these degrees ; and from o down to per-fectly noxious air, twenty degrees.

On adding one measure of nitrous air to two measuresof marine air, the mixture was so much reduced inbulk, as to stand at i\ degrees above 0Liverpool air, stood at 1 degree below oPod air, 4 degrees below o

Marine air therefore is 2^ degrees better than good com-mon air.—The air of Liverpool, 1 degree worse; and podair, or the air from the bladders of our sca-weed, 4 degreesworse. How it is, that the air contained in the bladdersof our sea weed, (which were fresh gathered) shoulddiffer from that examined by Dr. Priestley, I cannot tell.

The following was the method of procuring the airfrom sea water.—A quantity of clear rain water was first:boiled near four hours, so as to be freed from its air.—Intothis water, when the heat was sufficiently abated, wasput a bottle containing three gallons of sea water; andover the mouth of this bottle was inverted a cylindricalglass receiver, the mouth of which rested on the shoulderof the bottle.—After four hours, the heat of the boilingwater had raised about six ounce measures of air, or some-thing more than 55 of the bulk of the sea water em-

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