the island of Marajó did not exist, and the Amazonas formed an estuary opening widely to the sea. Not only were the lower plains of Pará flooded, but immense tracts of the province of Amazonas were covered with water. How far this salt water penetrated I do not know, but the shells of Pebas show that at one time its influence may have extended far up toward the Andes. At the time of the growth of the Santarem shells the water may have been brackish. With the gradual rise of the continent, not of the Andes alone, the fresh waters drove down the salt, the narrow river bed with its numerous channels was hollowed out of the emerging bottom, the sea began to attack and cut away the coast lands, and the present estuary condition of the mouths of the great river was brought about. I have not yet told half the story of the history of the Amazonian valley. It is by no means a simple one, and there are more episodes in it than we have hitherto dreamed. The Amazonas is a world, and no one man need hope to exhaust its wonders. Cornell University, Ithaca, N. Y., Feb. 23d, 1871. SCIENTIFIC INTELLIGENCE. I. CHEMISTRY AND PHYSICS. 1. On some Lecture-experiments.-(1.) To show the reciprocal combustion of the elements of water, JULIUS THOMSEN proceeds as follows: two narrow tubes of platinum, a centimeter long by a millimeter in diameter, formed by rolling up a piece of foil, are melted into the ends of two narrow glass tubes, and serve for the jets. These glass tubes pass through a rubber cork, distant from each other about a centimeter. One of them communicates with an oxygen gas-holder, the other with one containing hydrogen. The cocks of both are opened, the hydrogen is ignited and the stopper with its tubes, is introduced into a wide glass tube 10 or 15 centimeters long, slightly constricted at its lower end, and drawn to a narrow opening above. The hydrogen now burns in the oxygen, the platinum jets protecting the tubes. If now the oxygen be gradually shut off, a point will be soon reached where the amount present will be insufficient for the combustion of the hydrogen; the flame expands, and apparently disappears, but in an instant re-appears upon the oxygen tube, the oxygen now burning in hydrogen. On admitting more oxygen the flame passes over again to the hydrogen tube as at the first. This exchange may be repeated as often as is desired without extinguishing the flame and without danger, if the oxygen be let on and cut off with sufficient slowness. (2.) To show that oxygen may burn with a smoky flame, Thomsen uses the vapor either of turpentine or of benzol. Some benzol is heated to boiling in a long-necked flask closed with a stopper, through which passes a central tube a centimeter in diameter, and also a small lateral one, bent to one side. The vapor is ignited at the mouth of the large tube, and a small tube recurved at its lower end, through which a stream of oxygen is passing, is immediately inserted, the opening being closed by a cork which slides upon the small tube. The flame of the benzol vapor is thus extinguished and the oxygen burns in the vapor in the flask, with a smoky flame. The excess of vapor passes off through the small lateral tube. (3.) The processes of oxidation and reduction and the consequent changes in weight, Thomsen shows thus: cupric oxide is mixed with gum-water to a stiff paste and formed into cylinders, flattened on their sides, about a centimeter in diameter and 3 centimeters long. These are then dried, ignited, and reduced by hydrogen at the lowest temperature possible. A cylinder of metallic copper is thus obtained, very porous but sufficiently coherent to retain its form. These are wound with platinum wire, the two ends of which are melted into glass tubes by which they are handled. Two small tubulated glass bells are filled, the one with hydrogen, mouth downward, the other with oxygen, mouth upward, by displacement, the gases being allowed to flow slowly into them during the experiment. One of the copper cylinders is warmed to expel moisture, and immersed in the oxygen; it is raised at once to ignition and remains so until completely oxidized. It is then plunged into the bell-jar of hydrogen; it again begins to glow, the water formed runs down the side of the bell, and the cylinder is reduced to copper again. These combustions, the one in oxygen, the other in hydrogen, both evolving much light and heat, are very striking; and as the increase in weight of the cylinder by oxidation is almost a gram, it may be shown on an ordinary balance.-Ber. Berl. Chem. Ges., iii, 930, Dec. 1870. G. F. B. 2. On Ozone and Antozone.-ENGLER and NASSE have investigated the production of antozone by the method of Meissner (this Journal, II, xxxvii, 325, xxxviii, 18, 1, 213). They used an ozonizing tube 85 centimeters long, containing 28 wires enclosed in glass, and a coil sufficiently powerful to render the entire bundle of electrodes luminous in the dark. If the ozonized oxygen be passed through a U-tube 30 centimeters long and one centimeter in diameter, containing zinc-sodium in fragments, the ozone odor disappears completely. If the same tube be placed between the potassium iodide solution and the water over which the cloud appears, the formation of the cloud is not interfered with; thus showing that it is only the ozone and not the antozone which is destroyed by the zinc-sodium. Since Meissner concedes that the ozone must be removed to detect the antozone, it follows that were the antozone formed in the electrizing tube, the gas issuing from it after passing through the zinc-sodium tube and thus being deprived of ozone, should, on bubbling through water, produce a cloud; but this the authors find not to be the case. Moreover, they show that if the stream of oxygen issuing from the potassium iodide solution be passed through a tube 13 meters long, filled with fused calcium chloride, the antozone disappears; while ozone passed through such a tube is unaffected. But if the gas from the ozonizing tube be passed directly through this calcium chloride tube, then through potassium iodide solution and then through water, the cloud appears with full strength. Engler and Nasse hence infer that the antozone is formed when the ozone is destroyed in presence of water; and only then. Whence they conclude with v. Babo and Weltzien, that antozone is only hydrogen peroxide. In support of this view they give the following experiments: (1.) The stream of electrized oxygen, deozonized by a solution of potassium iodide, was passed through a spiral tube 1.5 meters long, and found to give the mist on passing through water. This spiral was then heated in a zinc chloride bath; as the temperature rose, the mist formed became less and less, disappearing completely at 170°, and returning again as the tube cooled. (2.) The stream of deozonized oxygen was passed through a short tube containing fragments of potassium hydrate, and then through four narrow tubes 60 centimeters long filled with glass-fragments; but its mist-forming power was hardly weakened; when these tubes were cooled to -20°, however, no mist appeared on passing it through water; and when two narrower and empty tubes were used, and the stream of gas continued for 24 hours, water condensed in them which gave the reactions of hydrogen peroxide. In conclusion, the authors show that the division of oxides by Schönbein into ozonides and antozonides is not well founded.-Ann. Ch. Pharm., cliv, 215. G. F. B. 3. On the Peroxides obtained by Electrolysis.-WERNICKE has analyzed the metallic films deposited upon the positive electrode in the electrolysis of solutions of certain metals. The following are his conclusions: (1.) The so-called peroxides, deposited by electrolysis from neutral or alkaline metallic solutions, are hydrates of the composition R", H2→ or (R2)→ ̧, 2H1⁄2Ð. (2.) The composition and the specific gravity of the bodies examined are as follows: 2 (3.) In thin layers these bodies exhibit the most beautiful interference-colors, which may be made available for the estimation of the refraction and dispersion of light. For purposes of technical metallochromy, the new colors of percobaltic hydrate are particularly to be noted, on account of the facility of their production and their permanence. (4.) All of these compounds are formed only with a weak current. If it be too strong, the precipitate thrown down on the positive pole contains less oxygen; until with a certain strength of current, oxygen only is evolved, the metal in the solution being unaffected. In this latter case the author supposes hydrogen peroxide to be formed, which decomposes the metallic perhydrate.-J. pr. Ch., II, ii, 419, Dec. 1870. G. F. B. 4. A Laboratory Text-book of Practical Chemistry; or Introduction to Qualitative Analysis. A guide to the course of Practical Instruction given in the Laboratories of the Royal College of Chemistry. With 90 engravings. By WM. G. VALENTIN, F.C.S. 8vo, pp. xii, 380. London, 1871. (John Churchill & Sons).-One of the chief difficulties, which beset the chemical instructor at the present day, is that of satisfactorily combining didactic with practical instruction; of teaching by text-book recitation on the one hand, and at the same time, of instructing by laboratory experimentation on the other. While it is unquestionably true that Chemistry cannot be properly learned solely by conimitting a volume to memory, it is equally true that it cannot be mastered by working solely with apparatus. Both the intellectual and the manual discipline are necessary. In the book before us, the author, fully recognizing these two phases of the subject, has attempted to combine them. We have here not a dry enumeration of facts, to be proved by experiment and then stored up individual and alone. Nor on the other hand, have we a book to be memorized and recited from, parrot-like. "It has been the author's endeavour," he says in his preface, " to enter only so far into theoretical considerations as was absolutely necessary to explain the laws which govern chemical changes, and to make the beginner practically familiar with the properties of elementary matter, and the most important forms of combination." The work is divided into two parts. Part First consists of "100 elementary exercises, introductory to General Chemistry and to Qualitative Chemical Analysis." Part Second is a course of Qualitative Analysis proper. In the first part, the student begins by performing simple and clearly discribed experiments with hydrogen and continues with oxygen, sulphur, chlorine, etc., and their compounds, the theoretical knowledge being gradually worked in as it is required. In the second part the usual division of the bases and acids into groups is followed, the whole being well arranged. Frankland's notation, wherein every chemical compound is formulated upon the type of the highest equivalence of its dominant atom, is used throughout. The atom of highest combining power in every molecule, is written first in heavy fullfaced type, thus, NO, Ago, SO,Zno", BNao,, etc. Graphic formulas are also freely employed. At the end of each chapter in both parts, are questions for examination, which are remarkably full and thorough. The reactions in all cases are given, and all the facts which help the student to a complete knowledge of the substance under examination are fully stated. Frequent examinations are recommended, and these are to be conducted like recitations. Copious tables in the appendix contain a condensed statement of the analytical processes, of the solubilities of salts, and of the metric system of weights and measures. We have rarely seen a better book to teach from than this. In its plan and the mode of carrying it out, its clearness, thoroughness, accuracy and attention to detail, it is, in our view, one of the AM. JOUR. SCI.-THIRD SERIES, VOL I, No. 3.-APRIL, 1871. best works of its kind in the English language. The wood-cuts are excellent and the style of the book is mechanically unexceptionable. G. F. B. 5. A Series of Chemical Problems for use in Colleges and Schools. Adapted for the Preparation of Students for the Government Science and Society of Arts Examinations; by T. E. THORPE, Ph.D., Professor of Chemistry in Anderson's University, Glasgow, with a Preface by Professor RoscoE, B.A., Ph.D. F.R.S. 67 pp. 16mo. London, 1870. (MacMillan; Manchester, James Galt & Co.)-This little volume contains an excellent collection of practical problems, such as every chemist has to deal with, founded upon the modern nomenclature and notation, with simple formulæ for their solution, and systematically and very clearly arranged. The best and most recent determinations are employed as data, and an appendix contains a number of very useful auxiliary tables of physical and chemical constants, logarithms, &c. The exercises relating to specific heat, latent heat, calorific power, and calorific intensity are especially fresh and valuable. The volume is well calculated to serve both as an aid to the student, and as a practical reference book. II. GEOLOGY AND NATURAL HISTORY. A. W. W. 1. California Geological Survey.-Ever since the first inauguration of this great work (in 1860), we have from time to time given our readers accounts of its progress, reporting the results of its explorations and the appearance of its publications, calling attention to the high ability and excellent spirit with which its labors were carried on, and expressing our hearty desire for its continuance, and completion upon the scale on which it was begun. Only two months ago (above, p. 70), its last published report was noticed in this Journal-the first volume of Ornithology, containing the land birds of the western side of the continent. Since then, the edition of the same with colored figures has appeared, and fully justifies the expectations entertained of it. The plan of giving highly colored illustrations in the text itself, on the same page with the letter-press, is quite new, and its success, which is complete, will be likely to make an era in the history of illustrated works on natural science. The admirable quality of the paper used, and the skill of the colorist, have united to produce a result which must satisfy the most critical taste. The second volume of Ornithology, which will contain the water-birds of the whole country, is in process of preparation. The volume of Conchology, which Dr. Carpenter undertakes, is likewise begun; and Prof. Brewer of Yale, formerly assistant on the survey, is rapidly working up the botanical material for publication, aided by Prof. Gray, and by others specially qualified for the work. The abundant collection of mammalian fossils is committed to Dr. Leidy for treatment. The fossil botany is undertaken by Prof. Lesquereux. The volumes already issued contain descriptions and figures of the invertebrate fossils by Mr. F. B. Meek |