Chapter 2

At the Royal Powder Works at Spandau, Prussia, frequent ignition of the powder at a certain stage of the process led to an examination of the machinery, when it was found that where, at certain parts, bronze pieces which were soldered were in constant contact with the moist powder, the solder was much corroded and in part entirely destroyed, and that in the joints had collected a substance which, on being scraped out with a chisel, exploded with emission of sparks. It was suspected that the formation of this explosive material was in some way connected with the corrosion of the solder, and the subject was referred for investigation to Rudolph Weber, of the School of Technology, at Berlin. The main results of his investigation are here given.

The explosive properties of the substance indicated a probable nitro-compound of one of the solder metals (tin and lead), and as the lead salts are more stable and better understood than those of tin, it was resolved to investigate the latter, in hope of obtaining a similar explosive compound. Experiments on the action of moist potassium nitrate on pure tin led to no result, as no explosive body was formed. Stannous nitrate, Sn(NO_{3})_{2}, formed by the action of dilute nitric acid on tin, has long been known, but only in solution, as it is decomposed on evaporating. By adding freshly precipitated moist brown stannous oxide to cool nitric acid of sp. gr. 1.20, as long as solution occurred, and then cooling the solution to -20 deg., Weber obtained an abundance of crystals of the composition Sn(NO_{3})_{2} + 20H_{2}O. They resemble crystals of potassium chlorate. They cannot be kept, as they liquefy at ordinary temperatures. An insoluble _basic_ salt was obtained by digesting an excess of moist stannous oxide in solution of stannous nitrate, or by adding to a solution of stannous nitrate by degrees, with constant stirring, a quantity of sodium carbonate solution insufficient for complete precipitation. Thus obtained, the basic salt, which has the composition Sn_{2}N_{2}O_{7}, is a snow-white crystalline powder, which is partially decomposed by water, and slowly oxidized by long exposure to the air, or by heating to 100 deg.. By rapid heating to a higher temperature, as well as by percussion and friction, it explodes violently, giving off a shower of sparks. This compound is also formed when a fine spray of nitric acid (sp. gr. 1.20) is thrown upon a surface of tin or solder. It is also formed when tin or solder is exposed to the action of a solution of copper nitrate, and thus formed presents the properties already described.

In this, then, we have a probable cause of the explosions occurring in the powder works; but the explanation of the formation of the substance is wanting, as potassium nitrate was shown not to give an explosive substance with tin. A thin layer of a mixture of sulphur and potassium nitrate was placed between sheets of tin and copper foil, and allowed to stand, being kept constantly moist. After a time the copper was found to have become coated with sulphide, while the tin was largely converted into the explosive basic nitrate. The conditions are obviously the same as those found in the powder machinery, where bronze and tin solder are constantly in contact with moist gunpowder. The chemical action is probably this: the sulphur of the powder forms, with the copper of the bronze, copper sulphide; this is oxidized to sulphate, which reacts with the niter of the powder, forming potassium sulphate and copper nitrate; the latter, as shown above, then forms with the tin of the solder the explosive basic nitrate, which, being insoluble, gradually collects in the joints, and finally leads to an explosion.--_Journal fuer Praktische Chemie._

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METALLIC THORIUM.

By L.F. NILSON.

The density of thorium as obtained by reducing the anhydrous chloride by means of sodium was found by Chydenius, 7.657 to 7.795. The author has obtained metallic thorium by heating sodium with the double anhydrous thorium potassium chloride, in presence of sodium chloride in an iron crucible. After treating the residue with water there remains a grayish, heavy, sparkling powder, which under the microscope appears to consist of very small crystals. Metallic thorium is brittle and almost infusible; the powder takes a metallic luster under pressure, is permanent in the air at temperatures up to 120 deg., takes fire below a red heat either in air or oxygen, and burns with a dazzling luster, leaving a residue of perfectly white thoria. If heated with chlorine, bromine, iodine, and sulphur, it combines with them with ignition. It is not attacked by water, cold or hot. Dilute sulphuric acid occasions the disengagement of hydrogen, especially if heated, but the metal is acted on very slowly. Concentrated sulphuric acid with the aid of heat attacks the metal very slightly, evolving sulphurous anhydride. Nitric acid, strong or weak, has no sensible action. Fuming hydrochloric acid and _aqua regia_ attack thorium readily, but the alkalies are without action. The metal examined by the author behaves with the reagents in question the same as did the specimens obtained by Berzelius. The mean specific gravity of pure thorium is about 11. Hence it would seem that the metal obtained by Chydenius must have contained much foreign matter. The specific gravity of pure thoria is 10.2207 to 10.2198. The equivalent and the density being known, we may calculate the atomic volume. If we admit that the metal is equivalent to 4 atoms of hydrogen, we obtain the value 21.1. This number coincides with the atomic volumes of zirconium (21.7), cerium (21.1), lanthanum (22.6), and didymium (21.5). This analogy is certainly not due to chance; it rather confirms the opinion which I have put forward in connection with my researches on the selenites, on certain chloro-platinates and chloro-platinites, etc., that the elements of the rare earths form a series of quadrivalent metals.

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[AMERICAN CHEMICAL JOURNAL.]

FRIEDRICH WOeHLER.

No one but a chemist can appreciate the full significance of the brief message which came to us a month ago without warning--"Woehler is dead!" What need be added to it? No chemist was better known or more honored than Woehler, and none ever deserved distinction and honor more than he. His life was made up of a series of brilliant successes, which not only compelled the admiration of the world at large, but directed the thoughts of his fellow workers, and led to results of the highest importance to science.

It is impossible in a few words to give a correct account of the work of Woehler, and to show in what way his life and work have been of such great value to chemistry. Could he himself direct the preparation of this notice, the writer knows that his advice would be, "Keep to the facts." So far as any one phrase can characterize the teachings of Woehler, that one does it; and though enthusiasm prompts to eulogy, let us rather recall the plain facts of his life, and let them, in the main, speak for themselves.[1]

[Footnote 1: See Kopp's "Geschichte der Chemie," iv., 440.]

He was born in the year 1800 at Eschersheim, a village near Frankfort-on-the-Main. From his earliest years the study of nature appears to have been attractive to him. He took great delight in collecting minerals and in performing chemical and physical experiments. While still a boy, he associated with a Dr. Buch, of Frankfort, and was aided by this gentleman, who did what he could to encourage in the young student his inclination toward the natural sciences. The first paper which bears the name of Woehler dates from this period, and is upon the presence of selenium in the iron pyrites from Kraslitz. In 1820 he went to the University of Marburg to study medicine. While there he did not, however, neglect the study of chemistry. He was at that time particularly interested in an investigation on certain cyanogen compounds. In 1821 he went to Heidelberg, and in 1823 he received the degree of Doctor of Medicine. L. Gmelin became interested in him, and it was largely due to Gmelin's influence that Woehler gave up his intention of practicing medicine, and concluded to devote himself entirely to chemistry. For further instruction in his chosen science, Woehler went to Stockholm to receive instruction from Berzelius, in whose laboratory he continued to work from the fall of 1823 until the middle of the following year. Only a few years since, in a communication entitled "Jugenderinnerungen eines Chemikers," he gave a fascinating account of his journey to Stockholm and his experiences while working with Berzelius. On his return to Germany, he was called to teach chemistry in the recently founded municipal trade school (Gewerbschule) at Berlin. He accepted the call, and remained in Berlin until 1832, when he went to Cassel to live. In a short time he was called upon to take part in the direction of the higher trade school at Cassel. He continued to teach and work in Cassel until 1836, when he was appointed Professor of Chemistry in Goettingen. This office he held at the time of his death, September 23, 1882.

In 1825 Woehler became acquainted with Liebig, and an intimate friendship resulted, which continued until the death of Liebig, a few years ago. Though they lived far apart, they met during the vacations at their homes, or traveled together. Many important investigations were conceived by them as they talked over the problems of chemistry, and many papers appeared under both their names, containing the results of their joint work. Among such papers may be mentioned: "On Cyanic Acid" (1830); "On Mellithic Acid" (1830); "On Sulphotartaric Acid" (1831); "On Oil of Bitter Almonds, Benzoic Acid, and Related Compounds" (1832); "On the Formation of Oil of Bitter Almonds from Amygdalin" (1837); and "On Uric Acid" (1837).

Of the papers included in the above list, the two which most attract attention are those "On the Oil of Bitter Almonds" and "On Uric Acid." In the former it was shown for the first time that in analogous carbon compounds there are groups which remain unchanged, though the compounds containing them may, in other respects, undergo a variety of changes. This is the conception of radicals or residues as we use it at the present day. It cannot be denied that this conception has done very much to simplify the study of organic compounds. The full value of the discovery was recognized at once by Berzelius, who, in a letter to the authors of the paper, proposed that they should call their radical proin or orthrin (the dawn of day), for the reason that the assumption of its existence might be likened to the dawn of a new day in chemistry. The study of this paper should form a part of the work of every advanced student of chemistry. It is a model of all that is desirable in a scientific memoir. The paper on uric acid is remarkable for the number of interesting transformation products described in it, and the skill displayed in devising methods for the isolation and purification of the new compounds. Comparatively little has been added to our knowledge of uric acid since the appearance of the paper of Liebig and Woehler.

It would lead too far to attempt to give a complete list of the papers which have appeared under the name of Woehler alone. In 1828 he made the remarkable discovery that when an aqueous solution of ammonium cyanate, CNONH_{4}, is evaporated, the salt is completely transformed into urea, which has the same percentage composition. It would be difficult to exaggerate the importance of this discovery. That a substance like urea, which up to that time had only been met with as a product of processes which take place in the animal body, should be formed in the laboratory out of inorganic compounds, appeared to chemists then to be little less than a miracle. To-day such facts are among the commonest of chemistry. The many brilliant syntheses of well-known and valuable organic compounds which have been made during the past twenty years are results of this discovery of Woehler.

In 1823 he published a paper on secretion, in the urine, of substances which are foreign to the animal organism, but which are brought into the body. He discovered the transformation of neutral organic salts into carbonates by the process of assimilation.

In 1832 he investigated the dimorphism of arsenious acid and antimony oxide. In 1841 he made the discovery that dimorphous bodies have different fusing points, according as they are in the crystallized or amorphous condition.

Among the more remarkable of his investigations in inorganic chemistry are those on methods for the preparation of potassium (1823); on tungsten compounds (1824); the preparation of aluminum (1827); of glucinum and yttrium (1828). In 1856, working with Ste. Claire Deville, he discovered crystallized boron.

Analytical methods were improved in many ways, and excellent new methods were introduced by him. Further, he did a great deal for the improvement of the processes of applied chemistry.

With Liebig he was associated in editing the "Annalen der Chemie and Pharmacie" and the "Handwoerterbuch der Chemie." He wrote a remarkably useful and popular "Grundriss der Chemie." The part relating to inorganic chemistry appeared first in 1831, and was in use until a few years ago, when Fittig wrote his "Grundriss" on the same plan, a work which supplanted its prototype.

The above will serve to give some idea of the great activity of Woehler's life, and the fruitfulness of his labors. While thus contributing largely by his own work directly to the growth of chemistry, he did perhaps as much in the capacity of teacher. Many of the active chemists of the present day have enjoyed the advantages of Woehler's instruction, and many can trace their success to the impulse gathered in the laboratory at Goettingen. The hand of the old master appears in investigations carried on to-day by his pupils.

Woehler's was not a speculative mind. He took very little part in the many important discussions on chemical theories which engaged the attention of such men as Dumas, Gerhardt, Berzelius, and Liebig, during the active period of his life. He preferred to deal with the facts as such; and no one ever dealt with the facts of chemistry more successfully. He had a genius for methods which has never been equaled. The obstacles which had baffled his predecessors were surmounted by him with ease. He was in this respect a truly great man.

Personally, Woehler was modest and retiring. His life was simple and unostentatious. He had a kindly disposition, which endeared him to his students, to which fact many American chemists who were students at Goettingen during the time of Woehler's activity can cordially testify. In short, it may be said deliberately that Woehler, as a chemist and as a man, was a fit model for all of us and for those who will come after us. Though he has gone, his methods live in every laboratory. His spirit reigns in many; could it reign in all, the chemical world would be the better for it.

I.R.

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LOUIS FAVRE, CONSTRUCTOR OF THE ST. GOTHARD TUNNEL.

It is now already a year that the locomotive has been rolling over the St. Gothard road, crossing at a flash the distance separating Basle from Milan, and passing rapidly from the dark and damp defiles of German Switzerland into the sun lit plains of Lombardy. Our neighbors uproariously feted the opening of this great international artery, which they consider as their personal and exclusive work, as well from a technical point of view as from that of the economic result that they had proposed to attain--the creation of a road which, in the words of Bismarck, "glorifies no other nation." As regards the piercing of the Gothard, the initiative does, in fact, belong by good right to the powerful "Iron Chancellor," so we have never dreamed of robbing Germany of the glory (and it is a true glory) of having created the second of the great transalpine routes, that open to European products a new gate to the Oriental world. It seems to us, however, that in the noisy concert of acclamations that echoed during the days of the fetes over the inauguration of the line, a less modest place might have been made for those who, with invincible tenacity and rare talent, directed the technical part of the work, and especially those 15 kilometers of colossal boring--the great St. Gothard Tunnel, which ranks in the history of great public works side by side with the piercing of the Frejus, and the marvelous digging of Suez and Panama.

We recall just now the names of those who, during nearly ten years, have contributed with entire disinterestedness to the completion of this colossal work. Over all stands a figure of very peculiar originality--that of M. Louis Favre, the general contractor of the great tunnel, whose name will remain attached to the creation of this work through the Helvetian Alps, like that of Sommeiller to the great tunnel of the Frejus, and that of De Lesseps to the artificial straits that henceforward join the oceans. Having myself had the honor of occupying the position of general secretary of the enterprise under consideration, I have been enabled to make a close acquaintance with the man who was so remarkable in all respects, and who, after passing his entire life in great public works, died like a soldier on the field of honor--in the depths of the tunnel.

I saw Favre, for the first time, in Geneva, in 1872, a few days after he had assumed the responsibility of undertaking the great work. He had been living since the war on his magnificent Plongeon estate, on the right bank of the lake. There was no need of dancing attendance in order to reach the contractor of the greatest work that has been accomplished up to the present time, for M. Favre was easy of access. We had scarcely passed five minutes together than we we were conversing as we often did later after an acquaintance of six years. After making known to him the object of my visit, the desire of being numbered among the _personnel_ of his enterprise, the conversation quickly took that turn of mirthfulness that was at the bottom of Favre's character. "This is the first time," said he to me, laughing, "that I ever worked with Germans, and I had not yet struck the first blow of the pick on the Gothard when they began to quibble about our contract of the 8th of last August. Ah! that agreement of August 8th! How I had to change and re-change it, later on. If this thing continues, we shall have a pretty quarrel, considering that I do not understand a word of the multiple interpretations of their _charabia_. I ought to have mistrusted this. But you see I have remained inactive during the whole of this unfortunate war. I was not made for promenading in the paths of a garden, and I should have died of chagrin if such inaction had had to be prolonged. When one lives, as I have, for thirty years around lumber yards, it is difficult to accustom one's self to the sedentary and secluded life that I have led here for nearly two years."

As he said, with just pride, Louis Favre had, indeed, before becoming the first contractor of public works in the world, lived for a long time in lumber yards. The years that so many other better instructed but less learned persons, who were afterward to gladly accept his authority, had given up to their studies, Favre had passed in the humble shop of his father, a carpenter at Chene, a small village at a half league from Geneva. It soon becoming somewhat irksome for him in the village, he left the paternal workbench to start on what is called the "tour of France." He was then eighteen years of age. Three years afterward, he was undertaking small works. It was not long ere he was remarked by the engineers conducting the latter, and he was soon called to give his advice on all difficult questions. Between times, Favre had courageously studied the principal bases of such sciences as were to be useful to him. In the evening, he made up at the public school what was lacking in his early instruction; not that he hoped to make a complete study for an engineer, but only to learn the indispensable. He was, before all things, a practical man, who made up for the enforced insufficiency of his technical knowledge by a _coup d'oeil_ of surprising accuracy. Here it may be said to me that the piercing of the great St. Gothard Tunnel was accompanied by considerable loss. That is true, but it must be recalled also that this colossal work was accomplished amid the most insurmountable difficulties which ever presented themselves. In spite of this, the cost of the tunnel per running foot was also a third less than that of the great Mont Cenis Tunnel.

When Favre undertook the St. Gothard, he already reckoned to his credit numerous victories in the domain of public works, especially in the construction of subterranean ones. The majority of tunnels of any length which, since the beginning of the establishment of railways, have been considered as works of some proportions (the Blaisy Tunnel, for instance), were executed by him, in addition to other open air works. So Favre reached the St. Gothard full of hope. The battle with the colossus did not displease him, and his courage and his confidence in the success of the work seemed to increase in measure as the circumstances surrounding the boring became more difficult. In the presence of the terrible inundation of the gallery of Airolo and the falling of aquiferous rocks, creating in the subterranean work so desperate a situation that a large number of very experienced engineers almost advised the abandonment of the works, Favre remained impassive. Amid the general apprehension, which, it may be readily comprehended, was felt in such a situation he made his confident and cheerful voice heard, reviving the ardor of all, and speaking disdainfully of "that insignificant Gothard, which would come out all right." The _personnel_ of the enterprise were not the only ones, however, who were uneasy over the constantly occurring difficulties in the way of the work, for the company itself and the Swiss Federal Council made known to Favre their fears that the execution of the work would be delayed. He, however, calmed their fears, and exposed his projects to them, and the seances always ended by a vote of confidence in the future of the undertaking. Favre certainly did not dissimulate the difficulties that he should have to conquer, but he execrated those who were timorous and always tried to put confidence into those who surrounded him. But, singular phenomenon, he ended by deceiving himself and, at certain times, it would not have been easy to prove to him that the St. Gothard was not the most easy undertaking in the world. Those who have lived around him know the jokes that he sometimes made at the expense of poor Gothard, which paid him back with interest, however, and did not allow itself to be pierced so easy after all.