That they are bits of a once larger mass is evident on their face. Their shape shows that they are not wholes but parts, while their constitution bespeaks them anything but elementary. Diagnosis of it yields perhaps their most interesting bit of news. For it shows their origin. Their autopsy proves them to contain thirty known elements, and not one that is new. The list includes all the substances most common on the Earth’s surface, which is suggestive; but, what is still more instructive, these are combined into minerals which largely differ from those with which we are superficially familiar. Professor Newton, whose specialty they were, has said: “In general they show no resemblance in their mechanical or mineralogical structure to the granitic and surface rocks of the Earth. One condition was certainly necessary in their formation, viz. the absence of free oxygen and of enough water to oxidize the iron.” Thus they are not of the Earth earthy; nor yet, poor little waifs, of the upper crust of any other body. [Illustration: SECTION OF METEORITE SHOWING WIDMANNSTÄTTIAN LINES. (Field Columbian Museum, Chicago.)] [Illustration: METEORITE, TOLUCA. (Field Columbian Museum, Chicago.)] In them prove to be occluded gases, which can be got out by heating in the laboratory, and which must have got in when the meteorites were still subjected to great heat and pressure. For only thus could these gases have been absorbed. Both such heat and such pressure accuse some great solid body as origin of this flotsam of the sky. Fragments now, they owe to its disruption their present separate state. This parent mass must have been much larger and more massive than the Earth, as the grate amount of occluded hydrogen, sometimes one-third the volume at 500° C., of the meteorite seems to testify. The two classes of meteorites, the stone and the iron, show this further by the very differences they exhibit between themselves. For both the amount and the proportions of the occluded gases in the two prove to be quite distinct. In the stones the quantity of gas is greater and the composition is diverse. In the stones carbonic acid gas is common, carbon monoxide rare; in the irons the ratio is just the other way. Thus Wright found in nine specimens of the iron meteorites:— CO₂ CO H CH₄ 11.5% 32.4% 54.1% 00% of the total; in ten of stone:— CO₂ CO H CH₄ 60.1% 3.4% 32.0% 2.1% The stones are much lighter than the iron, their specific gravities being as 3 to 7 or 8 for the metallic. The stones, therefore, came from a more superficial layer of the body torn apart than the iron, and the composition of their occluded gases bears this out. Those in the stones are such as we may conceive absorbed nearer the surface, those in the iron from regions deeper down.