the principle which has been explained, if it is sustained, as we believe, by the facts. A few only are briefly touched upon.

1. It follows that the hexagonal state of the elements may be one corresponding to 3R, or 3nR; that while zinc in the isometric state if such exists (about which there is doubt) is Zn; in the hexagonal it may be Zn3, the same state in which it exists in hexagonal oxyd of zinc. So also Pd, As, Sb, may represent the isometric state of the elements palladium, arsenic, antimony; but Pd3, As3, Sb3, the hexagonal; and so for other cases.

2. The oxyd of copper, CuO, which may also be written CuO, is dimorphous, it occurring both in isometric and orthorhombic forms; and the orthorhombic form is closely isomorphous with TiO2 in brookite-I: I and I: in the oxyd of copper being respectively 99° 39′ and 126° 29', and in brookite 99° 50′ and 126° 15'. This relation to TiO2 shows that the orthorhombic state of the cupric oxyd should have the formula CuO, or that of a deutoxyd, and the isometric alone that of CuO. And it indicates further that the element copper may exist theoretically, if not actually, in two corresponding poly

merous states.

3. As long since illustrated by Laurent, the protoxyds RO, sesquioxyds RO3, deutoxyds RO2, and other grades of oxyds RO3, RO5 (and the same in corresponding chlorids, sulphids, etc.), in which 1 part of oxygen balances, in its affinity, 1,,, etc., parts of the basic element (as is seen on dividing by the number of atoms of oxygen so as to reduce the oxygen in all the above formulas to 10), may be viewed as containing the basic element in as many different states as there are grades of the above compounds. For convenience these states may be designated by using the Greek letters as follows:

or the alpha, beta, gamma, delta and epsilon states. It is observed that 3RO-R303; 3(RO)=R1O3; 2(7RO)=RO2; 3(7RO)= RO2; 3($RO)=RO3; and so on: in other words, the one molecule RO corresponds to three of PRO; and in 3(BRO) there are as many atoms of the basic element PR as of O.

Now, if a sesquioxyd occurs in isometric crystals, as supposed to be true of Fe2O3 (but reasonably doubted), that sesquioxyd is not Fe2O3, but may be Fe3O. This is but the converse of the conclusion, stated above, that if a protoxyd occurs in hexagonal crystals it is not then RO, but may be R3Ó3. So in other cases: if oxyd of tin had an isometric as well as a tetragonal form, the former in the crystalline state should be SnO, and only the latter

SnO2. A metal in the different states R, R3, R1, has, accordingly, the same isomorphic power; and so also, 2R, 2R3, 2R1; and 3R, 3R, 3R. Hence under the principle explained

RO, RO, RO should be alike isometric in crystallization.

2(RO), 2(R2O), 2(RO) may be tetragonal “

3(RO), 3(R20), 3(R10) may be hexagonal "

66

Quartz, which is hexagonal silica, should, according to the above, be 3(SiO), or else 6(SiO), and not 2(Si40)=SiO3. SiO is hence unknown in the crystalline state; and if ever obtained crystallized it will in all probability have one of the forms of TiO2. Common uncrystallizing silica, or opal-silica, low in density, may be silica in the isometric form, or SiO, but with so feeble crystallizing power as never to exhibit any thing but the so-called colloid condition. Whether isometric silicon, crystals of which have been obtained artificially, is simply silicon in the alpha state, or not, cannot be at once decided; for it is probable that diamond, which is isometric carbon, is equivalent to C1, its density, and the product of the atomic weight by the specific heat, indicating this relation to graphite.* As "graphitoidal" silicon has turned out to be only isometric silicon, we have no chance for a comparison, like that with respect to carbon.

Anatase is probably TiO2, and rutile TiO4, the density of the latter being 4-2, of the former only 3.9. The relations of hausmannite and braunite (p. 90, note) accord with this, the latter containing two of huusmannite. Brookite is intermediate in density, and in the temperature of origin, and hence may be (TiO2). It would appear, therefore, that the species of highest polymerous state, rutile, forms at the highest temperature.

4. The views illustrated sustain the conclusion that the different states of elements represented above are fundamentally distinct: that Fe in the alpha state is related to all other metals that are in the same state, including K, Na (K,, Na, in the new system of chemistry), as well as Mg, Ca, etc.; that Fe, Cr, Co, in the beta state are of the same group of elements with aluminum in alumina that Fe, Mn, Cu, Pb in the gamma state should be classed with Ti, Sn.

5. Aid is given by the principle explained toward determining in many cases what are the accessory and what the dominant ingredients in a compound, and thence what should be regarded as its true constitution.

6. Crystallogeny hereby learns that quadratic or tetragonal symmetry in crystals depends on quadratic symmetry, or the recurrence

*For this inference with regard to the equivalent of carbon in the diamond I am indebted to Prof. G. F. Barker, who offered it while I was explaining to him the views contained in this paper.

of fours, in the number of atoms of the negative part of a compound; and hexagonal symmetry, in like manner, on the presence of triads or hexads of the same atoms. Moreover, on the view explained, the number of atoms of the more positive element or elements, in the simpler compounds at least, may be just equal to that of the negative. For since 3(RO)=R3Õ3, 3(ẞRO)=R1O3, and 3(RO) =RO3, there are, in these oxyds, as many atoms of «R, PR, JR, as of O; and if the elements may exist in these divided states, they may thus make with the O the crystallogenic molecule.

The precise arrangement of the constituent atoms in a molecule subsisting in any case, and producing the characteristics and special dimensions of the crystal, yet remains to be explained. This much may be safely deduced: that the negative atoms must be grouped-and in the systems here referred to, under quadrate or hexad symmetry-at or toward one extremity of the molecule, and the positive at or toward the opposite; and that the molecule in this way derives its polarity-a characteristic abundantly manifested in the formation, the forms, and the physical natures of crystals,* though not often apparent in mechanical effects, and which is in accordance with the most fundamental of nature's laws. The different constituent elements or parts of a compound may differ in degree of negativity or positivity, and even the same element may be present in opposite states; such constituents would have their places accordingly, though with subordinate groupings according to special affinities. In order not to be misunderstood, I here state, formally, what has been more than once implied in the foregoing, that, while, according to the principle advanced, tetragonal and hexagonal forms depend on the numbers 4 and 3, as explained, the presence of these numbers by no means necessitates the occurrence of these forms. Multitudes of examples illustrate this: the dimorphism of TiO2 is one. I would also remark that I express no opinion as to whether the molecule of a compound consists of the positive and negative atoms simply juxtaposed, or whether these so-called atoms are composed of particles, and there is a different disposition in the molecule; and assert only that, whatever the fact on this point, there is tetragonal symmetry in the constitution of the molecule in the tetragonal system, and hexagonal in the hexagonal system.

I leave the subject here, without discussing at present the methods by which orthorhombic and clinohedral forms are produced; only observing that orthorhombic and monoclinic forms occur under all numbers of atoms of the negative element, from 1 (or 2) as in sulphur, upward; and, therefore, although polym erism may turn the 2 of sulphur (and so, other numbers) into various multiples of the same, yet that the production of these forms does not depend simply on numbers.

* See articles I and II referred to on page 89.

ART. XIII.-The Glaciers of Alaska, Russian America; by WILLIAM P. BLAKE.*

ON approaching the northwest coast of America from the west the mountain chain of the interior is seen to be lofty and alpine in its character. The ridges are sharply serrated, and rise here and there into needle-like pinnacles, giving an outline against the sky that contrasts strongly with the gently sloping sides of the truncated cone of Edgecombe, a fine extinct volcano which marks the entrance to the harbor of Sitka.

The rocky peaks of the interior rise above broad fields of snow, which give birth to numerous glaciers, while Edgecombe, and the ridges upon the coast, are in great part covered with a dense forest of pines and firs. No glaciers are found upon the coast at Sitka or south of it, for under the influence of the warm currents of the Pacific, the climate is comparatively mild, while a short distance in the interior, the winters are almost Arctic in severity.

The principal stream in the vicinity of Sitka, is the Stickeen; which rises in the "Blue Mountains," opposite the head-waters of the Mackenzie, and flows in a general southeasterly direction parallel with the coast until it breaks through the mountains east, and a little north, of Sitka. When the snows are melting, the river becomes much swollen and is then navigable with difficulty by small steamboats for about 125 miles above its mouth. The valley is generally narrow and the river is not bordered by a great breadth of alluvial land.

In ascending this river one glacier after another comes into view; all of them are upon the right bank of the stream and descend from the inner slope of the mountain range. There are four large glaciers and several smaller ones visible within a distance of 60 or 70 miles from the mouth.

The first glacier observed, fills a rocky gorge of rapid descent, about two miles from the river, and looks like an enormous cascade. The mountains are greatly eroded by it, for it is overhung by freshly broken cliffs of rock evidently produced by the glacier.

The second glacier is much larger, and has less inclination. It sweeps grandly out into the valley from an opening between high mountains from a source that is not visible. It ends at the level of the river in an irregular bluff of ice, a mile and a half or two miles in length, and about 150 feet high. Two or more terminal moraines protect it from the direct action of the stream. What

* The observations upon which this article is based were made in May, 1863, while a guest on his Imperial Russian Majesty's Corvette "Rynda," Commander Banarguine, by whose courtesy the writer accompanied Lt. Pereleshin on a reconnaissance, in a whale boat, of the Stick een river, under the orders of Admiral Popoff.

-W. P. B.

at first appeared as a range of ordinary hills along the river, proved on landing to be an ancient terminal moraine, crescentshaped, and covered with a forest. It extends the full length of the front of the glacier. The following extract from my notes will answer for a description of the end of this glacier.

We found the bank composed of large angular blocks of granite mingled with smaller fragments and sand. It is an outer and older moraine, separated from a second one by a belt of marshland overgrown with alders and grass, and interspersed with ponds of water. Crossing this low space we clambered up the loose granitic debris of the inner moraine, which is quite bare of vegetation and has a recently formed appearance. These hills are from 20 to 40 feet high, and form a continuous line parallel with the outer and ancient moraine. From their tops we had a full view of the ice cliffs of the end of the glacier, rising before us like a wall, but separated from the moraine by a second belt of marsh and ponds. Here, however, there were no plants or trees. It was a scene of utter desolation. Great blocks of granite lay piled in confusion among heaps of sand or sand-cones or were perched upon narrow columns of ice-glacier tables apparently ready to topple over at the slightest touch. The edges of great masses of ice could be seen around pools of water, but most of the surface was hidden by a deposit of mud, gravel and broken rock. It was evident, however, that all this was upon a foundation of ice, for here and there it was uplifted, apparently, in great masses leaving chasms filled with mud and water. Over this fearful and dangerous place we crossed to the firmer and comparatively unbroken slope of ice at the foot of the bluff, and afterward had to climb over snow and ice only, in the attempt to reach the top of the glacier. From below it had appeared to us to be quite possible to accomplish this if we followed the least broken part of the slope, but it proved to be difficult, and finally impossible. Fissures which could not be seen from a short distance were met at intervals, some of them being so wide that we were forced to turn aside. As we ascended, the crevasses were more numerous but were generally filled with hard snow to which we occasionally trusted. The surface soon became precipitous and broken into irregular stair-like blocks with smooth sides and so large that it was impossible to make our way over them without ladders or tools to cut a foothold. Here we turned and enjoyed the sight of this great expanse of ice, broken into such enormous blocks and ledges. The sun illuminated the crevasses with the most beautiful aquamarine tints, passing into a deep sea-blue where they were narrow and deep. In one direction the ice presented the remarkable appearance of a succession of cones or pyramids with curved sides. In the oppo

AM. JOUR. SCI.-SECOND SERIES, VOL. XLIV, No. 130.-JULY, 1867.