In a letter dated September 8th, 1868, Dr. Butcher writes, from information received from the son of Dr. Long who had resided many years at Santa Rosa, that in the fall of the year 1837, there appeared over the town a most brilliant meteor, having a northwest direction. He describes it as most beautiful, lighting up the whole horizon, with a trail of brilliant light following in its progress. Shortly after its disappearance among the distant mountains, they heard a rumbling sound, immediately followed by a tremendous explosion.

From the report he thought it fell and exploded as it reached the earth, somewhere between Santa Rosa and the mountains, a distance of some thirty-five miles, and the next day he started with friends to examine the route, hoping to find it. After two days severe and rough riding they abandoned the search, and returned to town. Shortly afterward, an Indian brought a piece weighing 10 or 12 lbs. into Santa Rosa, supposing it to be silver, having found it some 90 miles northwest of the town, being in the same direction in which Dr. Long and his friends had been exploring, the doctor having been deceived as to distance, he only going to the base of the mountain, instead of crossing it and then following the valley for some 40 miles farther where I think his search would have been a success.

Dr. Butcher now undertook the search, after which he writes: "I have returned fully successful, and am making preparations to send on the iron. In making my arrangements, I hired eight Mexicans and two Indians as guides, and started into the mountains in a N. W. direction, the same as taken by Dr. Long, and found the iron about 90 miles from Santa Rosa. As no vehicle could go into the mountains by the route we entered, I spent two days in exploring a new road, whereby the ox teams could bring them out, and get them to Santa Rosa. They consist of eight pieces, varying from 290 lbs., which is the smallest, to 654 lbs., which is the largest, making a total of nearly 4000 lbs. Before the explosion, the weight must have been much greater, as it is not probable that I have secured the whole, and we know some was taken away by the Indians, who thought they found large masses of silver, and carried their specimens to Santa Rosa. It appears there is on record a statement of the meteor having passed over the city in 1837, and one of my guides relates as a fact, that at that time (1837) a Lepan Indian was riding one of their small ponies through the valley, when his stirrup struck against one of the masses, causing a ringing sound like silver. He dismounted, and was confirmed in his opinion of silver, and took away a piece 10 or 12 lbs. in weight, which he carried to Santa Rosa to sell. I have received from various sources, information relative to this

meteor, and all confirm me in the opinion that the autumn of 1837 is about the time of its fall. My party were in considerable danger while in the mountains, as we were encamped two miles from the regular trail, when some 300 Indians went through with a large number of their stolen horses."

Whether or not the time above specified is that of the fall of one or more of these irons, is a matter of little moment; the probabilities are, however, strongly in favor of it; nevertheless, it forms one of the most interesting groupings of meteoric irons known in any part of the world; especially, as the masses are solid and compact masses, and not fragile and half stony, as the Atacama iron, that may have been broken artificially after its fall, and the fragments scattered by Indians and explorers in search of silver. Each one of these masses merits a separate examination, which I hope to be able to give, sooner or later, to satisfy my mind on one or two points connected with their common physical structure and chemical composition. But I will not delay this paper until then.

Six of these masses have been brought to this country, weighing respectively 290, 430, 438, 550, 580 and 654 lbs. They are irregular compact masses, without any evidence of stony minerals. They belong to the softer irons, not very difficult to cut with the saw; as yet there has been but about one ounce detached from one of the masses, which has enabled me to make out the following description:

Specific gravity 7-692. It contains

This composition differs somewhat from the meteoric iron called Santa Rosa; but since examining that I have reason to believe that the quantity of nickel given is too small, some portion of it having remained with the iron; it being far more difficult than is usually supposed to separate accurately minute quantities of nickel from iron. Future examinations may prove that the Santa Rosa belongs to the group of irons under notice.

ART. XXXIX.—Atomic Ratio; by JOSIAH P. COOKE, Jr.

THE SO-called oxygen ratio, used by mineralogists, when interpreted by the new chemical philosophy, is simply the ratio between the total quantivalences of the several classes of radicals, which enter into the composition of a mineral. Indeed its whole value as a specific character in mineralogy depends upon the fact that it expresses this fundamental relation between the different atoms, which are associated in the molecules of the compound, and we propose therefore to call it the Atomic Ratio.

The possible hydrates of silicon may be represented by the general formula

n(H ̧ O ̧ Si)-mH ̧0=H1n-2m01n-2mSi, Om,

4

and every silicate may be regarded as derived from the corresponding hydrate by replacing the hydrogen atoms to a greater or less extent. Thus the composition of garnet is proven best by* iv R2, [R,] xiiO,, xiiSi,

ii

ii

vi

12

vi

in which R may be either Ca, Mg, Fe, Mn or Cr, and [R] either [Al,], [Fe,] or [Cr,]. Garnets have been analyzed, in which these several radicals are mixed together in every conceivable way consistent with this general formula, to which they all conform. This formula expresses all that is constant so far as the composition of the mineral is concerned, and the constant element is merely a definite ratio between the quantivalences, or atomicities, of the several classes of radicals taken collectively. In the last analysis this ratio is the one specific character, which distinguishes many mineral species, and hence its importance in the science of mineralogy.

When the general formula of a mineral is given we can easily calculate the atomic ratio. We have simply to multiply the number of atoms of each radical by its quantivalence and find the simplest ratio between these products, and this rule holds in whatever form the symbol may be written. Thus the

*The system of notation here used is explained at length in the author's work on Chemical Philosophy recently published. The main feature of the system consists in writing the symbols in a linear form and separating by commas the several radicals, which, although united to the same central or determinant atom, are otherwise independent of each other, Figures below the symbols indicate independent atoms, except when the symbol is enclosed in brackets. These show that the atoms are united among themselves to form a compound radical and that in consequence two or more of their affinities are closed. Dashes are used to point out the directions in which the several affinities of the principal radicals are exerted, but when the number of dashes required becomes inconveniently large they are indicated by Roman numerals. The Roman numerals above the symbols indicate as usual the quantivalence of the radicals.

atomic ratio of garnet is 6: 6:12 or 1:1:2. So in like manner the ratio for orthoclase is 2:6:24 or 1:3:12. On the other hand from the ratio we can as easily construct the symbol. For example the ratio in the case of anorthite is 1:3:4. By doubling this, (2:6:8) we make the first term divisible by 2, the second by 6, and the third by 4 the quantivalences of the several radicals associated in the mineral. Thus we have the

ii

skeleton as it were of the mineral R, [R], Si, and we now easily add the number of oxygen atoms required to "close" the molecular group, which gives us for the full symbol R, [R]vi ̧viSi,. In like manner from the ratio 1:3:6 we first

2

vi

8

ii

deduce the number of atoms of the three radicals, namely R, [R], Si, and then we add, besides the eight atoms of oxygen required to unite the basic radicals to the atoms of silicon, also two more to "close" the molecule.

The atomic ratio is easily deduced from the results of analysis by simply extending the usual method for finding the symbol of a body, whose molecular weight is unknown. We assume that the molecular weight is 100, and having divided in the usual way the per cent of each radical by its atomic weight we multiply the several quotients by the quantivalence of the respective radicals. Lastly we add together these products for each class of replacing radicals, and compare the several sums thus obtained. For example Moberg's analysis of the Bohemian pyrope gave the following results.

Dividing now each per cent by the atomic weight of the radical and multiplying by its quantivalence we obtain the following numbers :

whence we deduce the ratio

1-40:1-31:2-76 or 1:1:2 nearly.

It is usual in works on mineralogy to present the results of analysis on the old dualistic plan, as if the mineral were formed by the union of various basic anhydrids with silica. Starting with such data it is not, however, necessary to calculate the per cent of each radical in the assumed anhydrids before applying the above rule, because, obviously, by dividing the per cent of each anhydrid by its molecular weight we shall obtain the same quotients as before. For example, in the analysis of garnet cited above, where the data are given on one side in the usual form, we have

2

Si: SiO, 19.30: 41.35 or 19.30÷28=41.35÷60 and so for each of the other values.

In the symbols of the silicates as formerly written on the dualistic theory the atoms of oxygen were necessarily apportioned among the different radicals in proportion to their quantivalence, although this fundamental distinction between them was itself overlooked. Thus the general symbol of garnet would be written dualistically thus:

3RO, R,O,, 3SiO,

and it is evident that the number of oxygen atoms is in each case a measure of the relative quantivalences of the radicals, with which they are associated. Hence the atomic ratio might also be found by comparing together the quantities of oxygen, which the several assumed anhydrids contain, and this is the manner, in which the calculation has generally been made hitherto. Hence also the reason that the atomic ratio has been called the oxygen ratio and was long used in mineralogy before its true meaning was understood. But although the old method gives the same results as the new, it is not in harmony with our modern theories and is practically less simple. Moreover, the principle is far more general than the old method would imply and may be used with all classes of compounds as well as with those, in which the radicals are cemented together by oxygen. Furthermore it is frequently useful to compare the atomic ratios of the complex radicals which may be assumed to exist in different minerals, and interesting relations may frequently be discovered in this way, which the old method would entirely overlook. Thus for example the symbols of the more important feldspars, clays and zeolites may be written in the following form: