gen than the Albert coal analysed by Wetherell; while the idrialine or bitumen found with the mercury ores of Idria, approaches very nearly in composition to the bituminous coals 11, 12 and 13, with which many asphalts may be said to be isomeric. It is however probable that those oxygenized bitumens, unlike the coals, are products of the oxydation of naphtha or petroleum, by a process similar to that by which resins are derived from vegetable hydrocarbons. These formulas must be taken as representing not the true equivalents, but only the proportions of the elements in the bodies in question, which are in most cases mixtures of various substance. This is especially true of naphtha, which may be taken as the representative of pure unoxydised petroleum, and which is separated by distillation into oils of very different boiling points. The late analyses by Uelsmann of the rectified rock oil from Sehnde near Hanover, gave the formula C18H20, and according to De la Rue and Müller the greater part of the Rangoon petroleum consists of hydrocarbons in which the number of equivalents of hydrogen is a little greater than the carbon; one gave C2 6H28. Associated with these are however portions of bodies containing a less proportion of hydrogen, so that we may conceive the mean composition of petroleum to be represented, as in the preceding table, by equal equivalents of hydrogen and carbon; many forms of solid bitumen also, as ozokerite and hatchetine, have the same general composition.

By referring to what has been said above it will be seen that the final result of the third process of decomposition of woody fibre, in which the air being excluded, the oxygen is shared between the carbon and hydrogen, would be C2 0 Hs. A similar result would be obtained, with the simultaneous evolution of marsh gas, if we suppose 6 CO2 + 8 HO+3 CH2 to be removed from an equivalent of woody fibre, leaving C15 He = C2 0H 8 = C24H9.5, which approaches the composition of most bituminous coals and of idrialine. A farther elimination of marsh gas would leave a residue of pure carbon, and thus, as Bischof has suggested, vegetable matters may be converted into anthracite without the intervention of a high temperature.

The elimination of the whole of the oxygen in the form of carbonic acid would leave a compound with a large excess of hydrogen, of which it would be necessary to remove a portion in the form of water or marsh gas in order to reduce the residue to the composition of petroleum. We know of no combination

of carbon and hydrogen in which the number of atoms of hydrogen surpasses by more than two, those of hydrogen, the general formula being CnHn+2, so that oils like C18 H20 and C2 6H2 8 contain nearly the maximum quantity of hydrogen, and a body like C14H20, whose formation we have supposed above, could not exist, but must break up into marsh gas and some less hydrogenous oil like petroleum.

We do not know the precise conditions which in certain strata favor the production of petroleum rather than of lignite or coal, but in the fermentation of sugar, to which we may compare the transformations of woody fibre, we find that under different conditions it may yield either alcohol and carbonic acid, or butyric and carbonic acids with hydrogen, and even in certain modified fermentations the acetic, lactic and propionic acids, and the higher alcohols, like C10H12O2. These analogies furnish suggestions which may lead to a satisfactory explanation of the peculiar transformation by which, in certain sedimentary strata, organic matters have been converted into bitumen.

ARTICLE XVI.-Remarks on some of the Birds that breed in the Gulf of St. Lawrence. By HENRY BRYANT, M.D.

(Extracted from the Proceedings of the Boston Natural History Society, Vol. 8.)

The trip to Labrador, made by me the past summer, for the purpose of procuring specimens of the eggs of those sea-birds that breed there, and also to ascertain what changes, if any, had taken place in their economy since Audubon's visit, was unfortunately delayed till the 21st of June, so that the results were much less satisfactory than I hoped to have obtained. Instead of visiting Anticosti and the whole of the North shore, I was compelled to sail directly to the Bird Rocks, thence to Romaine, the nearest point on the North shore, and from thence, following the shore. line, to Chateau Beau at the outlet of the Straits of Belle Isle, the farthest point reached.

The season was remarkably stormy and cold, and I was informed by every one that such an inclement one had not been known for years. This also delayed my progress and added much to the difficulty of making researches, as many of the breeding places of this class of birds are accessible only in pleasant weather.

We sailed from Gaspé on the 21st, and arrived at the Bird Rocks on the morning of the 23rd; these are two in number, called the Great Bird or Gannet Rock, and the Little or North Bird; they are about three quarters of a mile apart, the water between them very shoal, showing that, at no very distant epoch, they formed a single island. They are composed entirely of a soft, reddish-brown sandstone, the strata of which are very regular and nearly horizontal, dipping very slightly to the S. W. The North Bird is much the smallest, and though the base is more accessible, the summit cannot, I believe, be reached, at least, I was unable to do so; it is the most irregular in its outline, presenting many enormous detached fragments, and is divided in one place into two separate islands at high water; the northerly one several times higher than broad, so as to present the appearance of a huge rocky pillar. Gannet Rock is a quarter of a mile in its longest diameter from S. W. to N. E. The highest point of the rock is at the northerly end, where, according to the chart it is 140 feet high, aud from which it gradually slopes to the southerly end, where it is from 80 to 100.

The sides are nearly vertical, the summit in many places overhanging. There are two beaches at its base on the southerly and westerly sides, the most westerly one comparatively smooth and composed of rounded stones. The easterly one, on the contrary, is very rough and covered by irregular blocks, many of large size and still angular, showing that they have but recently fallen from the cliffs above. This beach is very difficult to land on, but the other presents no great difficulty in ordinary weather; the top of the rock cannot, however, be reached from either of them. The only spot from which at present the ascent can be made, is the rocky point between the two beaches; this has probably, from the yielding nature of the rock, altered materially since Audubon's visit; at present, it would be impossible to haul a boat up from want of space. The landing is very difficult at all times, as it is necessary to jump from a boat, thrown about by the surf, on to the inclined surface of the ledge, rendered slippery by the fuci which cover it, and bounded towards the rock by a nearly vertical face. The landing once effected, the first part of the ascent is comparatively easy, being over large fragments and broad ledges, but the upper part is both difficult and dangerous, as in some places the face of the rock is vertical for eight or ten feet and the projecting ledges very narrow, and the rock itself so soft that it

cannot be trusted to, and in addition rendered slippery by the constant trickling from above and the excrements of the birds that cover it in every direction.

Since Audubon's time the fishery, which was carried on extensively in the neighborhood of Bryon Island, has failed, or at least is less productive than on the North shore, and I am inclined to think that at present the birds are but little disturbed, and that consequently their number, particularly of the Guillemots, has much increased. There was no appearance of any recent visit on the top of the rock, and though after making the ascent it was obvious that others had preceded us, still the traces were so faint that it was several hours before we succeeded in finding the landing-place. The birds breeding there, at the time of our visit, were Gannets, Puffins, three species of Guillemots, Razor-billed Auks, and Kittiwakes. These birds are all mentioned by Audubon, with the exception of Brünnich's Guillemot, and the Bridled Guillemot confounded by him with the common species. No other breedingplace on our shore is so remarkable at once for the number and variety of the species occupying it.

Of the seven species mentioned, I am not aware that three, namely, the Kittiwake and the Bridled and Brünnich's Guillemot, are known to breed at any other place south of the Straits of Belle Isle; of the remaining four, two, the Foolish Guillemot and Razorbilled Auk, are found at many other places and in large numbers; the Puffin in much greater abundance on the North shore, particularly at the Perroquet Islands, near Mingan and Bras D'Or; the Gannet at only two other points in the Gulf, at Percé Rock near Gaspé, which is perhaps even more remarkable than Gannet Rock, but is at present inaccessible; and at Gannet Rock near Mingan, which will soon be deserted by those birds in consequence of the depredations of the fishermen.

The following list of birds is not intended to comprise all those observed by me,—all the land birds are omitted, as well as those water birds to our present knowledge of which I could add nothing. Before leaving home I had flattered myself that I should have an opportunity of seeing some of the rarer Rapacious birds, or the Iceland or Greenland Falcon, Duck Hawk, &c. Strange as it may seem, during the whole of my visit to the North Shore, I saw only a single bird of this class-a fine Golden Eagle at Bras D'Or. I mention this, not as proof that those birds are unknown, for I frequently found on the shores unmistakable evidence

CAN. NAT.

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VOL. VI. No. 4.

of their visits, but to show with how much caution the results of any individual's experience should be received as positive evidence in Natural History.

As Audubon has generally given the average dimension only of the eggs of the birds described by him, which affords but a very incorrect idea of the variation in size and shape, I have made careful measurement of the extremes in length, breadth, and size of the eggs of all the varieties procured by me, not, however, including those which were evidently abnormal. In this class, I found eggs of the common Cormorant and Herring Gull; they were not more than one quarter of the average size, without exception contained nothing but albumen, and the shell was remarkably thick and strong. One egg of the Cormorant was not symmetrical in its longitudinal axis, and had the appearance of having been deposited in a soft state on a convex surface; in other respects it presented nothing remarkable. I have been lead to make these remarks because Naumann, in his description of the eggs of Uria troille, states that the eggs of very small size are found, caused by the birds laying more than their normal number. I do not think that this is the cause, as the eggs found by me were in nests with other eggs that presented no deviation from the ordinary shape or size.

Sometaria mollissima, Linn. This bird though constantly harassed by the fishermen and inhabitants, still breeds in great abundance along the whole extent of the North shore, and, as it is not gregarious during the breeding season, and ranges over such an immense extent of island and shore, it will probably continue to do so, even if unprotected, for many years. I found but few of their nests, placed under the shelter of the dwarf firs and junipers; their favourite breeding-blaces seemed to be the small grassy islands found in bays, and particularly those where small spots of turf were protected by a rock from the prevailing wind. On many of the islands a species of umbelliferous plant grows abundantly, the thick foliage of which forms an admirable shelter that they gladly avail themselves of. It is not often that many nests are found on one island; from one to a dozen is the ordinary number, though on Greenlet Island, in the Straits of Belle Isle, I found over sixty, probably not more than a quarter of the whole number, as two other persons besides myself were searching for them at the same time, and it is not probable that all the nests would be discovered; indeed, I found nearly as many returning