terrestrial hydrocarbons need not always be referred to an organic origin, but may have been formed in a purely inorganic way.

The occurrence of hydrocarbons in meteorites further shows that such meteorites could not have been subjected to any high degree of heat subsequent at least to the formation of these compounds, and that the heating of meteorites during their fall to the earth has in many cases been only superficial.

The trails of light, sometimes enduring several minutes, observed following in the wake of some meteors may perhaps indicate the presence of carbonaceous matter in those bodies. The stone shower which took place at Hessle was accompanied by luminous effects and with the stones fell a brownish-black powder which contained 71 per cent. carbonaceous matter. Other carbonaceous meteorites have fallen, however, without exhibiting any marked luminous phenomena.

Other compounds. Besides the above well-determined compounds a number of others have been reported at different times which are (1) present in insignificant amount or (2) their occurrence has not been confirmed, or (3) they may be of terrestrial origin. Among these a few may be mentioned: Quartz. This mineral, as is well known, is remarkable for its absence from meteorites. Yet it doubtless does occur in minute grains in a number of iron meteorites, since on dissolving them a residue is left, the grains of which possess the properties of quartz. Its occurrence in any stone or ironstone meteorite has never yet been established. Pyrite. This mineral has been reported a number of times, but sufficient proof to establish its identity has not been given. Von Siemaschko reported from the meteorite of Ochansk a brass-yellow pentagonal dodecahedron of which, however, he gave no measurements. Daubrée found in the meteorite of Senhadja, bronze-yellow grains insoluble in hydrochloric acid, soluble in aquaregia and altering easily to iron sulphate. While these and other observations suggest pyrite they are not conclusive. Salts soluble in water. Several of the carbonaceous meteorites as well as one or two others give

on evaporation of the water extract a residue of soluble salts reaching in quantity in one case as high as 10 per cent. of the These salts include nickel, calcium, magnesium, potas

mass.

sium, sodium and ammonium sulphates and chlorides.

Since the meteorites in which they occur are very porous in character and show other signs of alteration these compounds are usually considered to be formed by terrestrial modification of the meteorite and not to exist as original constituents. Daubrée, however, gives good reasons for regarding the sodium chloride which he found in the Lancé meteorite an original constituent. These reasons are that the meteorite had lain only three days in a clayey bed before it was picked up and no salt is known to have come near it. Breunnerite. This mineral was found in the meteorite of Orgueil occurring in the form of little transparent crystals. The identity of the mineral was established both by qualitative tests and by goniometric measurements. It has been suggested that it was of secondary origin. As it was found well within the interior of some masses, this, however, hardly seems likely. This is the only carbonate known from meteorites.

A number of other minerals have been reported from meteorites without sufficient grounds, according to the writer's view, to support the conclusion. Cohen considers them doubtful while Meunier accepts most of them. These are: Apatite, iolite, wollastonite, titanite, garnet, vesuvianite, mica, aragonite, leucite, cassiterite, hornblende, anthophyllite and orthoclase.

Mineral aggregates.-The different aggregates which the compounds above described form in different meteorites are too various to be recorded here in detail. For an account of

these, reference should be made to the elaborate classifications of Meunier,' Brezina2 or Wülfing.3

A few general observations may be made here, however, following the lines of the classification given by Wülfing. The Revision des Pierres Météoriques. Paris, 1897.

2 Annalen des k. k. Naturhistorischen Hofmuseums. Bd. X, Heft 3 u. 4. Vienna, 1896.

3 Die Meteoriten in Sammlungen. Tübingen, 1897, pp. 447-460.

iron-meteorites, as already indicated, are made up chiefly of nickel-iron, with schreibersite, troilite, daubréelite and a few other minerals occurring as accessories.

Of the ironstone meteorites the largest quantity are of the so-called pallasites, formed chiefly of chrysolite and nickel iron. Nine falls of this group are known, having a weight of 1742 kilograms. In the group known as siderophyrs, represented by one fall (82 kilos), of meteoritic matter, bronzite and tridymite are associated with the nickel-iron. In the group of mesosiderites (grahamites) represented by ten falls (483 kilos), of meteoritic matter, the nickel-iron is accompanied by chrysolite, bronzite, plagioclase, and augite. In the group lodranite, composed of one fall with a weight of 1 kilo, chrysolite and bronzite are associated with nickel-iron.

Passing to the stone meteorites the following groups and weights may be noted:

A. Stones rich in calcium and magnesium and containing little or no nickel-iron.

1. Angrite. Chiefly augite. One fall, weight 0.4kg.

2. Eukrite. Augite and anorthite. Four falls, weight 91kg.

3. Shergottite. Augite and maskelynite. One fall, weight 5kg.

4. Howardite. Augite, anorthite, bronzite, and chrysolite. Ten falls, weight 5kg.

B. Stones rich in magnesia and containing little or no nickel-iron. 1. Bustite. Diopside and bronzite.

Two falls, weight 1.7kg.

2. Chassignite. Chiefly chrysolite. One fall, weight 0.9kg.

3. Chladnite. Chiefly orthorhombic pyroxene. Four falls, weight 9kg. 4. Amphoterite. Chiefly chrysolite and bronzite. Three falls, weight 40kg. C. Stones rich in magnesia and consisting essentially of chrysolite, bronzite, nickel-iron, and iron sulphide. Here belong the great majority of stone meteorites.

A comparison of the constituents as above described with those of the crust of the earth brings to view some interesting similarities and contrasts. Under similarities may be noted the fact that the elements of meteorites are the same as those of the earth and that they unite according to the same chemical and physical laws. No new element has been discovered in meteorites and the chemical compounds of meteorites similar to those of the earth agree even to the details of their crystal form.

Under contrasts it may be noted that two agents which have affected largely the composition of the crust of the earth have been lacking either wholly or in part in the formation of meteorites. These agents are water and oxygen. The lack of water is proved by the fresh and unaltered character of the minerals found in meteorites and the absence of all hydrous minerals. Thus the chrysolite of meteorites is never found serpentinized nor are the pyroxenes changed to chlorite nor the feldspar to kaolin. Further, zeolites, micas, epidote, tourmaline and all other minerals in the formation of which water and water vapor play a part are entirely lacking from meteorites.

Similarity, oxygen, at least in excess, is lacking from the constituents of meteorites. Such substances as nickel-iron, schreibersite, and lawrencite, which make up so large a part of the composition of meteorites would rapidly have been oxydized had they been exposed to the action of oxygen as it occurs upon the earth. The silicates of meteorites are however oxydized compounds which show that oxygen is present to some degree in space.

Again, as noted by Cohen,' the important rock-forming minerals of the crust of the earth are either lacking or play an insignificant part in the formation of meteorites. Such are quartz, orthoclase, the acid plagioclases, the micas, the amphiboles, leucite, and nepheline. Vice versa, the chief mineral constitutents of meteorites occur in but insignificant amount upon the earth. Such are nickel-iron, the orthorhombic pyroxenes and chrysolite, while such compounds as schreibersite, cohenite, lawrencite, oldhamite, daubréelite and troilite rarely or never occur terrestrially. Looked at quantitatively then it may be said that terrestrial rocks abound in free silica, lime, alumina, and alkalies, while meteorites abound in iron, nickel and magnesia. Whether these quantitative differences would be maintained if the constitution of the earth as a whole could be compared with that of meteorites, is, as hinted at the beginning, doubtful. OLIVER C. FARRINGTON.

Op. cit., p. 323.

Among the innumerable phases of the great calamity which has fallen upon our country and the world in the tragic death of PRESIDENT MCKINLEY, the loss of a generous friend of science is by no means the least. The prosperity of the scientific bureaus under his administration has been as marked in improved organization and in method as in extension and in generous patronage, and the establishment of a new bureau in the interest of scientific and commercial precision is a laudable feature of special moment.