phate of iron may perhaps be applied in calico-printing as a discharge for indigo and also in bleaching blue rags for paper making.—Répertoire de Chimie Appliquée, Oct. 1859, p. 429.

[The observation that salts of the sesquioxyd of iron have the power of bleaching indigo and other organic coloring matters was first made by Prof. H. WURTZ of Washington and published two years since in this Journal (vols. xxv, 378, and xxvi, 52)—also in the Proc. of Amer. Assoc. 1858 and in several foreign journals-to him unquestionably belongs whatever credit may attach to the discovery-F. H. S.]

11. Aluminum Leaf-A Parisian gold beater, DEGOUSSE, has succeeded in obtaining leaves of aluminum as thin as those from gold and silver. The aluminum must be reheated repeatedly over a chafing dish during the process of beating. This leaf is less brilliant than that of silver but it is not so easily tarnished as the latter. It is easily combustible, taking fire when held in the flame of a candle and burning with an exceedingly intense white flame.

According to FABIAN, (Dingler's polyt. Journal, cliv, 438,) the chemical lecturer will find aluminum leaf to be well adapted, for exhibiting the characteristic properties of the metal. It dissolves, for example, with surprising rapidity in a solution of caustic alkali.

[A specimen of this leaf accompanies the description of it in Répertoire de Chimie Appliquée, Oct. 1859, p. 435, also Nov., p. 488.]

12. Critical and Experimental Contribution to the Theory of DyeingUnder this title a somewhat extended treatise by Prof. BOLLEY of Zurich has appeared in the L. E. and D. Philosophical Mag. [4] xviii, 481, Supplement to Dec. 1859.

Two questions have long been agitated among chemists interested in the theory of dyeing. (1.) In what part of the colored fibre is the coloring matter situated? Does it merely adhere to the surface, or docs it penetrate the entire substance of the cell-walls of such fibres as cotton and flax? Or lastly, in the case of such fibres is it stored up in the interior of the cells? (2.) What is the nature of the union between the dye and the fibre? Is it a chemical combination, or is it due to mere surface attraction? After comparing the various theories which have been advanced during the last century and discussing the merits of each, the author records the results of his own experiments, from which it appears that wool and silk in all cases where they have not been dyed with colors in a mere state of suspension* seem to be impregnated with the dye throughout their entire mass; while in the case of cotton, by far the larger portion of the coloring matter adheres to the surface of the fibre, the penetration of the cell-walls by the dye being either very slight or altogether wanting.

That the theory of W. Crum (L. E. and D. Phil. Mag,, April, 1844,compare this Journal, [2], xxviii, 125), in accordance with which the tubular form of the cotton fibres is an essential condition to their taking a dye, is unfounded, appears from the fact that the amorphous cotton-gelatine precipitated from its solution in cuprate of ammonia (see this Journal [2], xxvii, 118) may be mordanted and dyed like ordinary cotton. In like

* In which case the coloring matter only adheres as a crust to the surface of the fibre.

manner sulphate of baryta and other pulverulent mineral bodies may be mordanted and dyed with decoctions of dyewoods.

With regard to the nature of the force which binds the coloring matter to the fibre-whether or no it be chemical attraction? Bolley concludes that there is no sufficient reason for accepting the view, principally developed by Chevreul [and by Kuhlmann, Comptes Rendus. Tomes xlii, xliii et xliv], that dyeing is a direct consequence of chemical affinity. He believes that the power possessed by fibres of attracting certain bodies— whether salts or coloring matters or both-from their solutions, belongs to that class of phenomena which results from the action of finely divided mineral or organic bodies (charcoal or bone black for example,) on such solutions. The distinction between the action of charcoal and of fibres in thus removing saline matters, or dyes, from their solutions is one of degree only, the nature of the operation being identical in either case.

A given weight of well prepared animal charcoal can, as a rule, deprive a larger quantity of liquid of its color than an equal weight of wool or silk. Neither wool or silk can remove all the color from a solution as charcoal can, their effect extending only to a certain degree of dilution beyond which the particles of coloring matter resist their attraction. Dyes which may have been taken up without a mordant by wool or, especially, by silk may be removed again by long washing in water, a fact which is not true in the case of charcoal, or only to a very slight extent. The attraction of coloring matters for water is therefore more completely overcome by charcoal than by animal fibre; but even the cleanest vegetable fibres, as, unmordanted and completely bleached cotton, possess a certain power of attracting coloring matter. That cotton should have less effect in this matter than wool or silk is not surprising in view of the great difference in the structure of cotton fibre as compared with that of the two substances last mentioned. It is well known that wool and silk in consequence of their physical constitution belong to the class of strongly absorbent or hygroscopic substances, i. e. in consequence of a certain porosity or looseness of their particles they swell up when moist and become easily penetrated by a liquid throughout their entire mass; on the other hand the cell-walls of cotton fibres are denser, less penetrable and at the same time thinner and therefore unable to contain the same quantity of liquid.

It has been often urged that since fibres, especially those of animal origin, not only exert an attraction for salts &c. but also possess the power of decomposing some of them, their action must be chemical But in this respect the behavior of charcoal is similar to that of the fibres. So too with regard to the increased attraction for color exhibited by mordanted cotton which is on a par with the fact observed by Stenhouse that the decolorizing power of wood charcoal is considerably increased by precipitating alumina upon it.

According to the Author mordants act by producing insoluble colors (lakes). Their behavior towards coloring matters in solution must be ascribed to chemical affinity, with which however the fibres themselves have nothing to do.

The so-called substantive dyes become insoluble from some other cause than the addition of a mordant, for example oxydation of protoxyd of iron, or of white indigo.

That common alum with which wool or silk has been impregnated is able to attract coloring matter from solutions and precipitate it on the fibres depends not upon the strength of the chemical affinity of these fibres for the coloring matter, but upon the fact (experimentally proved by Bolley) that they become saturated with the alum which cotton does not. 13. Cellulose Digested by Sheep.-The researches of several German chemists* have proved that the cellulose of plants is by no means so indigestible a substance as was at one time supposed, but that on the contrary it is digested in considerable quantities, by the ruminants at least, especially when a portion of the food of the animal consists of some substance rich in oil.

In order to ascertain to what extent the digestibility of cellulose may depend upon its state of aggregation, SUSSDORF and A. STOCKHARDT have undertaken a series of experiments, of which only a very brief abstract can be here given. From their results it is evident that even the most compact kinds of cellulose can be in great measure digested by sheep. The experiments, commenced in July, 1859, were upon two wethers respectively five and six years old. These were fed: 1st, upon hay alone; 2d, upon hay and rye straw; 3d, hay and poplar wood sawdust which had been exhausted with lye; in order that the sheep should eat the sawdust it was found necessary to add to it some rye-bran and a small quantity of salt; 4th, hay and sawdust from pine wood mixed with bran and salt; 5th, hay, spruce sawdust, bran and salt; 6th, hay, paper-maker's pulp from linen rags and bran; after several unsuccessful attempts to induce the sheep to partake of the pulp when mixed with dry fodder it was at last given to them in a sort of paste or pap prepared by mixing bran with water. The experiments were continued until November, with the exception of a short intermission during which the animals were put to pasture in order that they might recover from the injurious effects— probably due to the resinous matters of the spruce wood,—of the fifth series of experiments.

The animals, as well as their food, drink and excrements were weighed every day. The amount of cellulose in the excrements was also daily determined by analysis. The composition of the food ingested having been previously ascertained.

It appeared that when the animals were fed: (1.) with hay (35 lbs. per week), 60 to 70 per cent of the cellulose contained therein was digested, i. e. it did not appear as such in the solid excrements. In this experiment the animals gained 7 lbs. in 18 days. (2.) With hay 14 lbs., and straw 7 lbs. (per week), 40 to 50 per cent of the cellulose of the straw was digested. The animals having lost 24 lbs. in 11 days. (3.) With hay 10 lbs., poplar saw-dust 54 lbs., bran 7 lbs. (per week), 45 to 50 per cent of the cellulose of the poplar wood was digested. The animals having gained 24 lbs. in 13 days. (4.) With hay 104 lbs., pine wood saw-dust 7 lbs., bran 10 lbs. (per week), 30 to 40 per cent of the cellulose of the pine wood was digested. The animals having gained 10 lbs. in 24 days. (5.) With hay 9 lbs., paper-maker's pulp 7 lbs., bran 14 lbs. (per week),

*For a portion of these interesting results, see: Agriculturchemische Untersuchungen und deren Ergebnisse angestellt u. gesammelt bei der landwirthschaftlichen Versuchstation in Mackern. Leipzig, WIGAND, 1852-57; also Die landwirthschaftlichen Versuchs-Stationen. Dresden, WERNER, 1858-59.-F. H. S.

80 per cent of the cellulose of the paper pulp was digested. The animals having gained 7 lbs. in as many days.

These experiments are to be continued, and more particularly with a view of ascertaining whether any nourishing effect is to be attributed to the cellulose.-STOCKHARDT's Chemischer Ackersman, 1860, No. 1, p. 51.

II. GEOLOGY.

1. Notes on the Geology of Nebraska and Utah Territory, (in a letter to one of the Editors from Dr. F. V. HAYDEN, dated Fort Laramie, March 3d, 1860.)—It will be seen by referring to the several memoirs, published in connection with my associate, Mr. Meek, and the second edition of a geological map of Nebraska and Kansas, that the great Lignite Tertiary Basin covers a vast area in the northwest. We find by personal observation that it occupies the greater portion of the country bordering on the upper Missouri, Yellow Stone and Big Horn rivers, that it extends far up into the Wind river valley and west along the North Platte road to the Sweet Water mountains, the Cretaceous rocks being exposed here and there by local upheavals, only except along the base of the mountains.

The lignite beds, which are well developed south of Fort Laramie extending along the base of the Laramie mountains to the Arkansas and southward, furnishing the coal or lignite in the vicinity of Denver City and probably forming a part of the same basin.

I have, in a former paper, suggested that fresh-water deposits near Fort Bridger are probably on a parallel with the estuary beds of Judith river, which at that time were not positively known to be Tertiary. The facts now in my possession show, with a good deal of certainty, that they form the lower portion of the great Lignite Basin. These estuary deposits, which occur in a number of localities in the west and northwest, as along the Grand and Cannon Ball rivers, at the mouth of the Judith on the Missouri, near the mouth of the Big Horn on the Yellow Stone, seem to have ushered in the tertiary epoch of the West, which had already been foreshadowed in Cretaceous formation No. 5,* by the Tertiary character of the Mollusca. We have already, in a former paper, noted the fact that a large portion of the fossils peculiar to the Cretaceous formation No. 5, are closely similar to true Tertiary types and in most of the localities the transition from No. 5 to the estuary beds is scarcely perceptible. On the North Platte, especially at Deer Creek, No. 5, which is very largely developed in this region, is not unfrequently thrust up through the overlying lignite beds, charged with its characteristic fossils. Along the bluff banks of the stream, where the beds are but slightly disturbed, the order of sequence of the strata is so perfect that I would not have been in doubt where to draw the line of separation until we came to the first seam of lignite, and even then I would have considered several beds of the Lignite formation as the upper portion of No. 5 had I not found in these lower lignite beds Unios and other fresh-water shells, together with impressions of leaves identical with those occurring so abundantly in the Upper Missouri and Yellow Stone Tertiary strata, and furthermore these beds on the

*The Cretaceous series of Nebraska has been divided into five formations, which for convenience have been numbered from the base in ascending order, 1, 2, 3, &c. SECOND SERIES, VOL. XXIX, No. 87.-MAY, 1860.

North Platte have now been traced continuously over the intervening country from the mouth of the Yellow Stone river to the Platte. I have ascertained the fact that the lignite beds along the North Platte are a continuation of those on the Upper Missouri, and that they extend in their full developement far up into the Wind river valley and along the Platte road to the Sweet Water mountains. As yet I have seen no indications of liguite in any of the divisions of the Cretaceous period except in formation No. 1 near the Big Sioux river on the Missouri and in a series of sandstones and shales near Fort Benton which we have referred to the same rock. As we proceed south and southwest in this region No. 1 seems to disappear gradually, and along the Laramie mountains I cannot determine its existence at all.

The geographical extension of the great Lignite Basin seems to me to be one of the most interesting questions in the geology of the West at the present time. Very little is known as yet of its limits and from the interesting facts collected by Dr. Engelmann and from other sources it must occupy a large area to the southward and westward from this point, and we already know that it extends far northward into the Hudson's Bay vicinity.

In regard to the White river Tertiary Basin its boundaries have been published with a good degree of accuracy. Its limits north of the Platte river are now well known, and as I have already stated in a former paper, one of the upper members of that basin is revealed along this river, and these, in their southern and southwestern extension, pass by a gradual transition into the Yellow Marl or superficial deposits of the Quaternary period. That the White river Tertiary beds are of later date than those of the Lignite Basin, is clearly shown by the former having been observed resting conformably upon the latter in several localities.

2. Note on Prof. Newberry's criticisms of Prof. Heer's determination of species of North American Fossil Plants, in a letter to Prof. Asa Gray, Cambridge. Dear Sir: When I offered for publication in this Journal, the translation of part of a letter from Prof. O. Heer, concerning some fossil plants of the Tertiary, I was far from supposing that any of the statements of my learned friend would not appear satisfactory to every one interested in the study of our American Palæontology. Much less could I foresee that those statements would be construed in a manner that I do not think quite justifiable. As Prof. Heer's letter was published without his knowledge and sanction, I am forced, much to my regret, to defend his position against Dr. Newberry, a personal friend also, and a true and faithful pioneer in the field of our botanical paleontology.

I know nothing about the discussion on the Cretaceous formations and fossils, except what has been published in this Journal. And although last year, during my connection with the State Geol. Survey of Arkansas, I had the opportunity of examining well exposed strata at different stages of the Cretaceous, I was unable to find there any fossil plants, and therefore I have never seen as yet an American Cretaceous plant. Thus I can take my arguments only from the statements of Dr. Newberry himself. It is unnecessary to recall the five points in discussion.

The two first statements are, even from the assent of Dr. Newberry, satisfactorily explained by the insufficiency for exact determination of