arrangement, so far as could be made out from the information collected. In no part of the lead region are the crevices developed on a more extensive scale, or with so much regularity, as in the Dubuque district. The characteristic form of occurrence of the ore is the cave-opening, or expansion of the vertical crevice. into a cave or chamber, whose walls are sometimes lined with a heavy incrustation of pure galena, but which are more generally partially filled with clay and loose masses of rock, mixed with fragments of ore, derived from the decomposition of the material which once filled the opening, or metalliferous portion of the rock. Some of these caves have yielded several millions of pounds of galena, from a space very limited in depth and length, It is a favorite idea among those who have little acquaintance with mining operations in general, or who wish to dispose of abandoned lead-mines to Eastern capitalists, that the lead crevices extend indefinitely downwards, and that the only reason why deep mining has not been carried on in this region is that the miners have not sufficient skill or capital to work down to any considerable depth. It has also been insisted on by the same class of persons, that the Lower Magnesian limestone is a good mineral-bearing rock, and that lead-mining may be carried on in it with profit, while the expediency of sinking shafts through the Upper Sandstone into this rock in search of ore, has often been discussed and urged by them. In regard to these points, of so much economical importance to the lead-region, the Report has the following:* "There is very little evidence that the crevices continue to be productive, in the Dubuque district, even as low down as the Blue limestone; and it is certain from the study of the whole region, that they are everywhere completely cut off by the Upper sandstone. In no instance, so far as we have been able to learn, have the lodes been found to extend more than a short distance into the sandstone, or to be productive of galena in that rock. It is true that, in some localities, ore has been found in the limestone underlying this sandstone (the Lower Magnesian), when this rock occupies the surface; but the deposits in that geological position are very few in number, and the ore limited in quantity; we have yet to learn of a single instance in which diggings in that rock have been profitable for any length of time. But, again, even if the Lower Magnesian were a good mineral-bearing rock, there would be little encouragement to continue sinking from the Galena limestone, through the sandstone, into the underlying sandstone; for there is no reason to suppose that a crevice, after being entirely interrupted in the sandstone, would be resumed in the limestone below, at a point exactly in the line of direction of the workings above. A miner would be no more justified in * Report p. 462. sinking through the sandstone, in the expectation of meeting a continuation of his crevice in the Lower Magnesian, than be would be in commencing a shaft anywhere at random in this rock, without regard to surface-indication, and expecting to strike a valuable lode. He might possibly find one; but the chances would be more than ten-thousand to one that he would not." That the amount of lead produced in the Upper Mississippi region is gradually diminishing is evident from the statistics; the maximum produce of these mines was in the years 1845-47, when it was nearly 25,000 tons per annum. At present it amounts to less than half that. In answer to the question, what can be done to develop the mining interest of this region, a systematic topographical and mining survey of the whole lead-bearing region is urged as an indispensable preliminary to future successful explorations. A more or less symmetrical disposition of the crevices will be found to prevail, and from the symmetry of the known, the position of the unknown may possibly be ascer tained. There is no doubt that heavy bodies of ore yet remain concealed under the thick covering of drift, which makes surface explorations so expensive, and that a large amount of labor is wasted in fruitless search for workable lodes which might be more profitably expended if more systematically directed. The existence of zinc ore in sufficient quantity and under suitable conditions with reference to fuel, labor, and a market, is pronounced highly questionable. Gold is not to be looked for, except in the most minute quantity, a caution inserted with special reference to the gold-fever raging in Central Iowa, at the time this portion of the Report was passing through the press. Specimens of considerable size may, possibly, have found their way out of the pockets of returned California miners, into the soil of Iowa. In closing the Report, we would express our earnest hope that the survey so well begun, may be continued to its completion, and that other volumes as valuable may soon follow. ART. XVI.-Correspondence of Prof. Jerome Nicklès, dated Paris, October 26th, 1858. Scientific Association at Carlsruhe.-We ask our readers this time to go beyond the bounds of France across the Rhine. We need make no apology for this, as science is of all countries, and the announcement of scientific news is our special duty as correspondent of the American Journal. The German Scientific Associations are generally highly interesting, as much for the men that attend them as the subjects discussed. Few meetings however have been as important as this 34th, held at Carlsruhe, the capital of the Grand Duchy of Baden. It was remarkable for the sympathy between the government and the people, and also for the men there gathered and the papers brought forward. The first of the chemists and physicists of Germany were there; and geology, mineralogy, botany, zoology, and medicine had equally distinguished representatives. As the meeting was divided into sections, we could not hear all, and selected those departments according with our own predilections,-physics and chemistry; and we therefore confine our communications to facts brought out in these two sections. The presidents of the section of chemistry were successively Liebig, Wöhler, Schönbein, and on the declinature of Bunsen, H. Rose. The sessions began on the 17th of September. Schlossberger on the property of ammoniacal oxyd of copper dissolving cellulose. This property was made known some years since by Schweitzer. Not only cellulose but also silk is soluble in this reagent. The ammoniacal sulphate of copper acts as a solvent only from the excess of oxyd of copper present. Mr. Schlossberger finds that the solvent power increases with the proportion of copper, and that the hydrate of copper dissolved in ammonia acts better than the sulphate. The cupro-ammoniacal liquid does not dissolve gum, dextrine, starch, while it does dissolve filtering paper. The salts, and especially the alkaline salts, precipitate this solution of cellulose, and sulphate of copper has the same effect. The precipitate shows no trace of organization or crystallization; and it does not appear to differ in percentage composition from that of cellulose. These same alkaline salts do not precipitate the solution of silk, and the fact may be made the basis of a process for separating silk from cotton. The solution of cellulose is precipitated also by alcohol, a concentrated solution of honey, gum Arabic, or dextrine. The cupro-ammoniacal liquid has no action on pyroxyline or collodion. Inuline, chitine, conchyoline, are insoluble in it. Mr. Schlossberger has found that the ammoniacal hydrate of nickel, NiO HN, acts like the salt of copper. The solution of silk is however a fine blue in the latter and a yellowish brown in the former. J. Nickles on the diffusion of fluorine and the means of detecting it.— In this paper, the subject of which has been briefly presented in this Journal before, the following conclusions were arrived at. 1. There is fluorine in the blood, but less than has been supposed. 2. There are only small traces of fluorine in bones. After Berzelius, the proportion is 3 grams in 100 grams of the calcareous part of bones; but we have shown that there is hardly 0.05 in a kilogram. 3. The sources from which the animal organization may derive fluorine are: (a) potable waters; (b) vegetable substances, although some contain so little that it is necessary to experiment on a kilogram at least of ashes, and on the products of evaporation of some thousand litres of water. Besides, some mineral waters are a source containing fluorine in even a large proportion-a fact that may explain the efficiency of certain mineral waters that are feebly mineralized, such as those of Plombières, and Mont d'Or, etc. 4. The water of the Seine taken at Paris, is one of those containing the least fluorine. 5. Of the rivers of France, one of the richest in fluorine is that of the La Somme near Amiens. 6. Mineral waters vary in amount of fluorine; the richest examined are, the waters of Contrexeville, Antogast, Rippoldsau, Geilnau and Châtenois (Bas-Rhin). Reactions may be obtained from a litre of these waters. 7. The Atlantic affords no sensible amount even from 300 litres, showing thus a striking difference between marine and mineral waters. 8. The law of the diffusion of fluorine may be thus expressed: There is fluorid of calcium in all waters containing bicarbonate of lime, and therefore there may be fluorine in all rocks and minerals formed in a sedimentary way. 9. There are two sources of error in the usual method of detecting fluorine-one arising from the fact that sulphuric acid alone will attack glass, and the other from the fact that this acid often contains small quantities of fluohydric acid. 10. These sources of error are eliminated from my methods-by using (a) quartz crystals in place of glass, and (b) sulphuric acid free from fluohydric acid. 11. The solvent which I use is chlorhydric acid, which, with a little care, may be found free from fluorine in the shops. In the memoir I point out the circumstances under which such a chlorhydric acid may be produced in the manufacture in the large way. On the Preparation of Ozone by von Babo, and by Messrs. Bunsen and Magnus.-The apparatus in which ozone is obtained by the combustion of phosphorus, permits of separating the gas from the phosphorous acid with which it is ordinarily mixed. This result is attained by causing the gas to pass through a solution of chromic acid. This acid not only oxydizes the phosphorous acid, but, as Baumert has shown, it increases the quantity of ozone; for after the washing there is more ozone than before, evidently because the oxydation of phosphorous acid is itself a cause of ozonization. Von Babo has succeeded in drying ozone so far as to render it anhydrous, whence it follows that ozone, or at least this kind of ozone, cannot be confounded with the hydrogenated ozone HO3 discovered by Baumert. Bunsen and Magnus, who made remarks on this paper, expressed the opinion that we must admit two kinds of ozone, one allotropic oxygen and the other a hydrogenated compound. Schönbein on Ozone.-See page 19 of this volume. Notices by Prof. Erdmann, of Leipzig.-The name of Erdmann is in high regard among chemists, as well from his fine researches, as from his being the early teacher of the lamented Gerhardt.* Erdmann had the insight to detect the future greatness of this distinguished chemist and to open the treasures of his science to his pupil-so early deceased— whose labors have so greatly enlarged the horizon of chemistry. It was our good fortune to make the personal acquaintance of the first master of our lamented friend, and to obtain from him information on the * See our biog. notice of Gerhardt, this Jour., Jan., 1857, p. 102. obscure points of his youth and his early scientific career. From this source we derive our knowledge of several new facts first established in his laboratory. (1.) Blistering principle of Ranunculus sceleratus.-This principle occurs under the form of an acrid oil, which on the tongue is changed into a white mass of anemonine and anemonic acid. This transformation occurs in the plant during desiccation, but the vegetable then loses all its bitterness. (2.) Action of certain Metallic Salts on ligneous fibres.-It is well known that to preserve wood, and particularly the ties of railways, it is usual to impregnate them with a solution of sulphate of copper. This salt combines with the fibre in a manner so intimate as to preserve it from the action of water, which has no effect to dissolve out the copper salt even when the prepared wood is submerged. This change happens only to wood in its natural state, for if the fibre is purified from albuminous matters, &c., although the copper salt appears to combine perfectly with it, on the least action of water it is dissolved out. solutions of sulphate of copper, in fact, remove the azotized substances from wood. Dilute (3.) Solubility of Sulphate of Baryta.-This salt, one of the most insoluble of all substances in water, is soluble in water containing nitrate of ammonia, a concentrated solution dissolving sulphate of baryta in considerable proportion. On new hydrocarbons and a new property of these bodies; by Mr. FRITZSCHE, of St. Petersburgh. These hydrocarbons have been discovered in the tar resulting from the distillation of wood. They possess the peculiarity of forming beautiful and well defined crystalline compounds with picric acid, as well as those known of naphthaline and benzine. As the researches of Fritzsche have been some time published, we refer the reader to his memoir. Manufacture of Soda and Baryta; by MR. KUHLMANN.--The new facts established by Mr. Kuhlmann, of Lille, owe their discovery to a desire to render salubrious the manufacture of carbonate of soda by the process of Leblanc, which has heretofore been predjudicial to the public health, owing to the vast volumes of chlorhydric acid gas which have pervaded the atmosphere near such establishments. Mr. Kuhlmann has succeeded in avoiding this nuisance by the following process: He conducts the acid gases over masses of native carbonate of baryta, which arrest the hydrochloric acid, forming chlorid of barium. This salt, by means of dilute sulphuric acid, is changed into sulphate of baryta, which is now in great demand in the arts under the name of blanc fixe (permanent white). He manufactures 2000 kilograms per day. Another new fact established by Mr. Kuhlmann relates to the economy of the residues of chlorid of manganese, resulting from the production of chlorine and hypochlorites. These residues retain a large quantity of chlorine, and Mr. Kuhlmann, who is one of the principal manufacturers, estimates the loss from this source to be not less than two million francs in France alone. This skilful chemist has contrived two uses for these residues. Either he transforms them into chlorid of barium by means of carbon and sul |