Chapter XI: TECHNOLOGY--American Workshops.--The care of tools and practice (4)

The Cadiz peninsula has for centuries been legitimately renowned, for, turn by turn, Phenicians, properly so called, Carthaginians, Romans, Goths, Arabs and Spaniards have made of it the preferred seat of their business and pleasure. In his so often unsparing verses, Martial, even, celebrates with an erotic rapture the undulating suppleness of the ballet dancers of _Gades_, who are continued in our day by the _majas_ and _chulas_.

For an epoch anterior to that of the Latin poet, we have the testimony, among others, of Strabo, who describes the splendors, formerly and for a long time famous, of the temple of Hercules, and who gives many details, whose accuracy can still be verified, concerning various questions of topography or ethnography. Thus the superb tree called _Dracaena draco_ is mentioned as growing in the vicinity of _Gadeira_, the Greek name of the city. Now, some of these trees still exist in certain public and private gardens, and attract so much the more attention in that they are not met with in any other European country. However, although historically Cadiz finds her title to nobility on every page of the Greek and Latin authors, and although her Phenician origin is averred, nowhere has such origin, in a monumental and epigraphic sense, left fewer traces than in the Andalusian peninsula. A few short legends, imperfectly read upon either silver or bronze coins, and that was all, at least up to recent times. Such penury as this distressed savants and even put them into pretty bad humor with the Cadiz archaeologists.

To-day, it seems that the ancient Semitic civilization, which has remained mute for so long in the Iberic territory, is finally willing to yield up her secret, as is proved by the engravings which we present to our readers from photographs taken _in situ_. It is necessary for us to enter into some details.

In 1887 there were met with at the gates of Cadiz, at about five meters beneath the surface of the earth, three rude tombs of shelly limestone, in which were found some skeletons, a few small bronze instruments and some trinkets--the latter of undoubted oriental manufacture.

In one of these tombs was also inclosed a monolithic sarcophagus of white marble of the form called anthropoid and measuring 2.15 m. in length by 0.67 in width. This sarcophagus is now preserved in the local museum, whose director is the active, intelligent and disinterested Father Vera. Although this is not the place to furnish technical or scientific explanations, it will be permitted us to point out the fact that although it is of essentially oriental manufacture, our anthropoid has undoubtedly undergone the Hellenistic influence, which implies an epoch posterior to that of Pericles, who died in 429 B.C. The personage represented, a man of mature age with noble lineaments and aquiline nose, has thick hair corned up on the forehead in the form of a crown, and a beard plaited in the Asiatic fashion. As for the head, which is almost entirely executed in round relief, that denotes in an undoubted manner the Hellenistic influence, united, however, with the immutable and somewhat hierarchical traditions of Phenician art. The arms are naked as far as to the elbow, and the feet, summarily indicated, emerge from a long sheath-form robe. As for the arms and hands, they project slightly and are rather outlined than sculptured. The left hand grasps a fruit, the emblem of fecundity, while the right held a painted crown, the traces of which have now entirely disappeared. It suffices to look at this sarcophagus to recognize the exclusively Phenician character of it, and the complete analogy with the monuments of the same species met with in Phenicia, in Cyprus, in Sicily, in Malta, in Sardinia, and everywhere where were established those of Tyre and Sidon, but never until now in Spain.

On another hand, for those of our readers who are interested in archaeology, we believe it our duty to point out as a source of information a memoir published last year by our National Society of Antiquaries. Let us limit ourselves, therefore, to fixing attention upon one important point: The marble anthropoid was protected by a tomb absolutely like the rude tombs contiguous to it.

The successive discoveries since the third of last January at nearly the same place, and at a depth of from 3 to 6 meters beneath the surface, of numerous _Inculi_ absolutely identical as to material and structure with those of which we have just spoken, is therefore a scientific event of high importance. Those discoveries, which were purely accidental, were brought about by the work on the foundations of the Maritime Arsenal now in course of construction at the gates of Cadiz. Our Fig. 1 represents the unearthing of the _loculi_ on the 14th of April, and on the value of which there is no need to dwell. As to the dimensions, it is easy to judge of these, since the laborer standing to the left of the spectator holds in his hand a meter measure serving as a scale. It will suffice to state that the depth of each tomb is about two meters, and that upon the lower part of three of the parallelopipeds there exist pavements of crucial appearance. Finally, nothing denoted externally the existence of these sarcophagi jealously hidden from investigation according to a usage that is established especially by the imprecations graven upon the basaltic casket now preserved in the Museum of the Louvre, and which contained the ashes of Eshmanazar, King of Sidon.

Space is wanting to furnish ampler information. Our object is simply to call attention to a zone which is somewhat neglected from a scientific point of view, and which, however, seems as if it ought to offer a valuable field of investigation to students of things Semitic, among whom, as well known, our compatriots hold a rank apart, since it is to them that falls the laborious and very honorable duty of collecting and editing the inscriptions in Semitic languages.

On another hand, although in the beginning the sepulchers were taken to pieces and carried away (two of them imperfectly reconstructed may be seen in the garden of the Cadizian Museum), there will be an opportunity of making prevail the system of maintaining _in situ_ the various monuments that may hereafter be discovered. Thus only could one, at a given moment, obtain an accurate idea of what the Phenician necropolis of Cadiz was, and allow the structures that compose it to preserve their imposing stamp of rustic indestructibility.

The excavation is being carried on at this very moment, and a bronze statuette of an oriental god and various trinkets of more or less value have just enriched the municipal collection. Let us hope, then, as was recently predicted by Mr. Clermont Ganneau, of the Institute, that some day or another some Semitic inscription will throw a last ray of light upon the past, which is at present so imperfectly known, of Phenician Cadiz.--_L'Illustration._

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PREHISTORIC HORSE IN AMERICA.

_To the Editor of the Scientific American_:

Apropos to Professor Cope's remarks before the A.A.A.S. at Washington, reported in SCIENTIFIC AMERICAN, September 12, inclose sketch of a mounted man, whether on a horse or some other mammal, is a question open to criticism.

The figure seems incomplete--whether a cloven foot or toes were intended, cannot say.

A large fossil horse was exhumed in the marsh north of Granada, when ditching in 1863. Then Lake Managua's outlet at Fipitapa ceased its usual supply of water to Lake Nicaragua. When notified of the discovery the spot was under water. Only one of the very large teeth was given to me, which was forwarded to Prof. Baird, of Smithsonian--Private No. 34.

When Lake Nicaragua was an ocean inlet, its track extended to foot hills northward. Its waterworn pebbles and small bowlders were subsequently covered by lake deposit, during the time between the inclosure and break out at San Carlos. In this deposit around the lake (now dry) fossil bones occur--elephas, megatherium, horse, etc. The large alluvium plains north of lake, cut through by rivers, allow these bones to settle on their rocky beds. This deposit is of greater depth in places west of lake.

Now, if we suppose these animals were exterminated in glacial times, it remains for us to show when this was consummated.

Subsequent to the lake deposit and exposure no new proofs of its continuance are found.

1. This deposit occurred after the coast range was elevated.

2. Elevation was caused by a volcanic ash eruption, 5 or 6 of a series. (Geologically demonstrated in my letters to _Antiquarian_ and _Science_.)

3. Coast hills inclosed sea sediment, now rock containing fossil leaves.

4. Wash from this sediment, carried with care, formed layers of sandstone, up to ceiling.

5. This ceiling was covered with elaborate inscriptions.

6. The inscription sent you was a near neighbor to cave.

7. Another representing a saurian reptile on large granite bowlder is also a neighbor (a glacial dropping).

8. Old river emptying into Lake Managua reveals fossil bones; moraines east of it are found.

From these data we see the glacial action was prior to the sedimentary rock here, and had spent its force when elevation of coast range occurred. No nearer estimate is possible.

As the fossil horse occurs here, our mounted man may have domesticated him, and afterward slaughtered for food like the modern Frenchman. Unfortunately Prof. Cope did not find a similar inscription.

EARL FLINT. Rivas, Nicaragua, October 27, 1891.

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FURTHER RESEARCHES UPON THE ELEMENT FLUORINE.

By A.E. TUTTON.

Since the publication by M. Moissan of his celebrated paper in the _Annales de Chimie et de Physique_ for December, 1887, describing the manner in which he had succeeded in isolating this remarkable gaseous element, a considerable amount of additional information has been acquired concerning the chemical behavior of fluorine, and important additions and improvements have been introduced in the apparatus employed for preparing and experimenting with the gas. M. Moissan now gathers together the results of these subsequent researches--some of which have been published by him from time to time as contributions to various French scientific journals, while others have not hitherto been made known--and publishes them in a long but most interesting paper in the October number of the _Annales de Chimie et de Physique._ Inasmuch as the experiments described are of so extraordinary a nature, owing to the intense chemical activity of fluorine, and are so important as filling a long existing vacancy in our chemical literature, readers of _Nature_ will doubtless be interested in a brief account of them.

IMPROVED APPARATUS FOR PREPARING FLUORINE.

In his paper of 1887, the main outlines of which were given in _Nature_ at the time (1887, vol. xxxvii., p. 179), M. Moissan showed that pure hydrofluoric acid readily dissolves the double fluoride of potassium and hydrogen, and that the liquid thus obtained is a good conductor of electricity, rendering electrolysis possible. It will be remembered that, by passing a strong current of electricity through this liquid contained in a platinum apparatus, free gaseous fluorine was obtained at the positive pole and hydrogen at the negative pole. The amount of hydrofluoric acid employed in these earlier experiments was about fifteen grms., about six grms. of hydrogen potassium fluoride, HF.KF, being added in order to render it a conductor. Since the publication of that memoir a much larger apparatus has been constructed, in order to obtain the gas in greater quantity for the study of its reactions, and important additions have been made, by means of which the fluorine is delivered in a pure state, free from admixed vapor of the very volatile hydrofluoric acid. As much as a hundred cubic centimeters of hydrofluoric acid, together with twenty grms. of the dissolved double fluoride, are submitted to electrolysis in this new apparatus, and upward of four liters of pure fluorine is delivered by it per hour.

This improved form of the apparatus is shown in the accompanying figure (Fig. 1), which is reproduced from the memoir of M. Moissan. It consists essentially of two parts--the electrolysis apparatus and the purifying vessels. The electrolysis apparatus, a sectional view of which is given in Fig. 2, is similar in form to that described in the paper of 1887, but much larger.

The U-tube of platinum has a capacity of 160 c.c. It is fitted with two lateral delivery tubes of platinum, as in the earlier form, and with stoppers of fluorspar, F, inserted in cylinders of platinum, _p_, carrying screw threads, which engage with similar threads upon the interior surfaces of the limbs of the U-tube. A key of brass, E, serves to screw or unscrew the stoppers, and between the flange of each stopper and the top of each branch of the U-tube a ring of lead is compressed, by which means hermetic closing is effected. These fluorspar stoppers, which are covered with a coating of gum lac during the electrolysis, carry the electrode rods, _t_, which are thus perfectly insulated. M. Moissan now employs electrodes of pure platinum instead of irido-platinum, and the interior end of each is thickened into a club shape in order the longer to withstand corrosion. The apparatus is immersed during the electrolysis in a bath of liquid methyl chloride, maintained in tranquil ebullition at -23 deg.. In order to preserve the methyl chloride as long as possible, the cylinder containing it is placed in an outer glass cylinder containing fragments of calcium chloride; by this means it is surrounded with a layer of dry air, a bad conductor of heat.

The purifying vessels are three in number. The first consists of a platinum spiral worm-tube of about 40 c.c. capacity, immersed also in a bath of liquid methyl chloride, maintained at as low a temperature as possible, about -50 deg.. As hydrofluoric acid boils at 19.5 deg. (Moissan), almost the whole of the vapor of this substance which is carried away in the stream of issuing fluorine is condensed and retained at the bottom of the worm. To remove the last traces of hydrofluoric acid, advantage is taken of the fact that fused sodium fluoride combines with the free acid with great energy to form the double fluoride HF.NaF. Sodium fluoride also possesses the advantage of not attracting moisture. After traversing the worm condenser, therefore, the fluorine is caused to pass through two platinum tubes filled with fragments of fused sodium fluoride, from which it issues in an almost perfect state of purity. The junctions between the various parts of the apparatus are effected by means of screw joints, between the nuts and flanges of which collars of lead are compressed. During the electrolysis these leaden collars become, where exposed to the gaseous fluorine, rapidly converted into lead fluoride, which being greater in bulk causes the joints to become hermetically sealed. In order to effect the electrolysis, twenty-six to twenty-eight Bunsen elements are employed, arranged in series. An ampere meter and a commutator are introduced between the battery and the electrolysis apparatus; the former affording an excellent indication of the progress of the electrolysis.

As the U-tube contains far more hydrofluoric acid than can be used in one day, each lateral delivery tube is fitted with a metallic screw stopper, so that the experiments may be discontinued at any time, and the apparatus closed. The whole electrolysis vessel is then placed under a glass bell jar containing dry air, and kept in a refrigerator until again required for use. In this way it may be preserved full of acid for several weeks, ready at any time for the preparation of the gas. Considerable care requires to be exercised not to admit the vapor of methyl chloride into the U-tube, as otherwise violent detonations are liable to occur. When the liquid methyl chloride is being introduced into the cylinder, the whole apparatus becomes surrounded with an atmosphere of its vapor, and as the platinum U-tube is at the same instant suddenly cooled the vapor is liable to enter by the abducting tubes. Consequently, as soon as the current is allowed to pass and fluorine is liberated within the U-tube, an explosion occurs. Fluorine instantly decomposes methyl chloride, with production of flame and formation of fluorides of hydrogen and carbon, liberation of chlorine, and occasionally deposition of carbon. In order to avoid this unpleasant occurrence, when the methyl chloride is being introduced the ends of the lateral delivery tubes are attached to long lengths of caoutchoue tubing, supplied at their ends with calcium chloride drying tubes, so as to convey dry air from outside the atmosphere of methyl chloride vapor. If great care is taken to obtain the minimum temperature, this difficulty may be even more simply overcome by employing a mixture of well pounded ice and salt instead of methyl chloride; but there is the counterbalancing disadvantage to be considered, that such a cooling bath requires much more frequent renewal.

CHEMICAL REACTIONS OCCURRING DURING THE ELECTROLYSIS.

In the paper of 1887, M. Moissan adopted the view that the first action of the electric current was to effect the decomposition of the potassium fluoride contained in solution in the hydrofluoric acid, fluorine being liberated at the positive pole and potassium at the negative terminal. This liberated potassium would at once regenerate potassium fluoride in presence of hydrofluoric acid, and liberate its equivalent of hydrogen:

KF = K + F.
K + HF = KF + H.

But when the progress of the electrolysis is carefully followed, by consulting the indications of the amperemeter placed in circuit, it is found to be by no means as regular as the preceding formulae would indicate. With the new apparatus, the decomposition is quite irregular at first, and does not attain regularity until it has been proceeding for upward of two hours. Upon stopping the current and unmounting the apparatus, the platinum rod upon which the fluorine was liberated is found to be largely corroded, and at the bottom of the U-tube a quantity of a black, finely divided substance is observed. This black substance, which was taken at first to be metallic platinum, is a complex compound containing one equivalent of potassium to one equivalent of platinum, together with a considerable proportion of fluorine.

Moreover, the hydrofluoric acid is found to contain a small quantity of platinum fluoride in solution. The electrolytic reaction is probably therefore much more complicated than was at first considered to be the case. The mixture of acid and alkaline fluoride furnishes fluorine at the positive terminal rod, but this intensely active gas, in its nascent state, attacks the platinum and produces platinum tetrafluoride, PtF_{4}; this probably unites with the potassium fluoride to form a double salt, possibly 2Kl.PtF_{4}, analogous to the well known platinochloride 2KCl.PtCl_{4}; and it is only when the liquid contains this double salt that the electrolysis proceeds in a regular manner, yielding free fluorine at the positive pole, and hydrogen and the complex black compound at the negative pole.

PHYSICAL PROPERTIES OF FLUORINE.

Fluorine possesses an odor which M. Moissan compares to a mixture of hypochlorous acid and nitrogen peroxide, but this odor is usually masked by that of the ozone which it always produces in moist air, owing to its decomposition of the water vapor. It produces most serious irritation of the bronchial tubes and mucous membrane of the nasal cavities, the effects of which are persistent for quite a fortnight.

When examined in a thickness of one meter, it is seen to possess a greenish yellow color, but paler, and containing more of yellow, than that of chlorine. In such a layer, fluorine does not present any absorption bands. Its spectrum exhibits thirteen bright, lines in the red, between wave lengths 744 and 623. Their positions and relative intensities are as follows:

[lambda] = 744 very feeble. | [lambda] = 685.5 feeble
740 " | 683.5 "
734 " | 677 strong
714 feeble. | 640.5 "
704 " | 634 "
691 " | 623 "
687.5 " |

At a temperature of -95 deg. at ordinary atmospheric pressure, fluorine remains gaseous, no sign of liquefaction having been observed.

METHODS OF EXPERIMENTING WITH FLUORINE.

When it is desired to determine the action of fluorine upon a solid substance, the following method of procedure is adopted. A preliminary experiment is first made, in order to obtain some idea as to the degree of energy of the reaction, by bringing a little of the solid, placed upon the lid of a platinum crucible held in a pair of tongs, near the mouth of the delivery tube of the preparation apparatus. If a gaseous or liquid product results, and it is desirable to collect it for examination, small fragments of the solid are placed in a platinum tube connected to the delivery tube by flexible platinum tubing or by a screw joint, and the resulting gas may be collected over water or mercury, or the liquid condensed in a cooled cylinder of platinum. In this manner the action of fluorine upon sulphur and iodine has been studied. If the solid, phosphorus for instance, attacks platinum, or the temperature of the reaction is sufficiently high to determine the combination of platinum and fluorine (toward 500 deg.), a tube of fluorspar is substituted for the platinum tube. The fluorspar tubes employed by M. Moissan for the study of the action of phosphorus were about twelve to fourteen centimeters long, and were terminated by platinum ends furnished with flanges and screw threads in order to be able to connect them with the preparation apparatus. If it is required to heat the fluorspar tubes, they are surrounded by a closely wound copper spiral, which may be heated by a Bunsen flame.

In experimenting upon liquids, great care is necessary, as the reaction frequently occurs with explosive violence. A preliminary experiment is therefore always made, by allowing the fluorine delivery tube to dip just beneath the surface of the liquid contained in a small glass cylinder. When the liquid contains water, or when hydrofluoric acid is a product of the reaction, cylinders of platinum or of fluorspar are employed. If it is required to collect and examine the product, the liquid is placed along the bottom of a horizontal tube of platinum or fluorspar, as in case of solids, connected directly with the preparation apparatus, and the product is collected over water or mercury if a gas, or in a cooled platinum receiver if a liquid.

During the examination of liquids a means has accidentally been discovered by which a glass tube may be filled with fluorine gas. A few liquids, one of which is carbon tetrachloride, react only very slowly with fluorine at the ordinary temperature. By filling a glass tube with such a liquid, and inverting it over a platinum capsule also containing the liquid, it is possible to displace the liquid by fluorine, which, as the walls are wet, does not attack the glass. Or the glass tube may be filled with the liquid, and then the latter poured out, leaving the walls wet; the tube may then be filled with fluorine gas, which being slightly heavier than air, remains in the tube for some time. In one experiment, in which a glass test tube had been filled with fluorine over carbon tetrachloride, it was attempted to transfer it to a graduated tube over mercury, but in inclining the test tube for this purpose the mercury suddenly came in contact with the fluorine, and absorbed it so instantaneously and with such a violent detonation that both the test tube and the graduated tube were shattered into fragments. Indeed, owing to the powerful affinity of mercury for fluorine, it is a most dangerous experiment to transfer a tube containing fluorine gas, filled according to either the first or second method, to the mercury trough; the tube is always shattered if the mercury comes in contact with the gas, and generally with a loud detonation. Fluorine may, however, be preserved for some time in tubes over mercury, provided a few drops of the non-reacting liquid are kept above the mercury meniscus.

For studying the action of fluorine on gases, a special piece of apparatus, shown in Fig. 3, has been constructed. It is composed of a tube of platinum, fifteen centimeters long, closed by two plates of clear, transparent, and colorless fluorspar, and carrying three lateral narrower tubes also of platinum. Two of these tubes face each other in the center of the apparatus, and serve one for the conveyance of the fluorine and the other of the gas to be experimented upon. The third, which is of somewhat greater diameter than the other two, serves as exit tube for the product or products of the reaction, and may be placed in connection with a trough containing either water or mercury.

The apparatus is first filled with the gas to be experimented upon, then the fluorine is allowed to enter, and an observation of what occurs may be made through the fluorspar windows. One most important precaution to take in collecting the gaseous products over mercury is not to permit the platinum delivery tube to dip more than two or at most three millimeters under the mercury, as otherwise the levels of the liquid in the two limbs of the electrolysis U-tube become so different, owing to the pressure, that the fluorine from one side mixes with the hydrogen evolved upon the other, and there is a violent explosion.

ACTION OF FLUORINE UPON THE NON-METALLIC ELEMENTS.

_Hydrogen._--As just described, hydrogen combines with fluorine, even at -23 deg. and in the dark, with explosive force. This is the only case in which two elementary gases unite directly without the intervention of extraneous energy. If the end of the tube delivering fluorine is placed in an atmosphere of hydrogen, a very hot blue flame, bordered with red, at once appears at the mouth of the tube, and vapor of hydrofluoric acid is produced.

_Oxygen._--Fluorine has not been found capable of uniting with oxygen up to a temperature of 500 deg.. On ozone, however, it appears to exert some action, as will be evident from the following experiment. It was shown in 1887 that fluorine decomposes water, forming hydrofluoric acid, and liberating oxygen in the form of ozone. When a few drops of water are placed in the apparatus shown in Fig. 3, and fluorine allowed to enter, the water is instantly decomposed, and on looking through the fluorspar ends a thick dark cloud is seen over the spot where each drop of water had previously been. This cloud soon diminishes in intensity, and is eventually replaced by a beautiful blue gas--ozone in a state of considerable density. If the product is chased out by a stream of nitrogen as soon as the dense cloud is formed, a very strong odor is perceived, different from that of either fluorine or ozone, but which soon gives place to the unmistakable odor of ozone. It appears as if there is at first produced an unstable oxide of fluorine, which rapidly decomposes into fluorine and ozone.

_Nitrogen_ and _chlorine_ appear not to react with fluorine.

_Sulphur._--In contact with fluorine gas, sulphur rapidly melts and inflames. A gaseous fluoride of sulphur is formed, which possesses a most penetrating odor, somewhat resembling that of chloride of sulphur. The gas is incombustible, even in oxygen. When warmed in a glass vessel, the latter becomes etched, owing to the formation of silicon tetrafluoride, SiF_{4}. Selenium and tellurium behave similarly, but form crystalline solid fluorides.

_Bromine_ vapor combines with fluorine in the cold with production of a very bright but low temperature dame. If the fluorine is evolved in the midst of pure dry liquid bromine, the combination is immediate, and occurs without flame.

_Iodine._--When fluorine is passed over a fragment of iodine contained in the horizontal tube, combination occurs, with production of a pale flame. A very heavy liquid, colorless when free from dissolved iodine, and fuming strongly in the air, condenses in the cooled receiver. This liquid fluoride of iodine attacks glass with great energy and decomposes water when dropped into that liquid with a noise like that produced by red-hot iron. Its properties agree with those of the fluoride of iodine prepared by Gore by the action of iodine on silver fluoride.

_Phosphorus._--Immediately phosphorus, either the ordinary yellow variety or red phosphorus, comes in contact with fluorine, a most lively action occurs, accompanied by vivid incandescence. If the fluorine is in excess, a fuming gas is evolved, which gives up its excess of fluorine on collecting over mercury, and is soluble in water. This gas is phosphorus pentafluoride, PF_{5}, prepared some years ago by Prof. Thorpe. If, on the contrary, the phosphorus is in excess, a gaseous mixture of this pentafluoride with a new fluoride, the trifluoride, PF_{3}, a gas insoluble in water, but which may be absorbed by caustic potash, is obtained. The trifluoride, in turn, combines with more fluorine to form the pentafluoride, the reaction being accompanied by the appearance of a flame of comparatively low temperature.

_Arsenic_ combines with fluorine at the ordinary temperature with incandescence. If the current of fluorine is fairly rapid, a colorless fuming liquid condenses in the receiver, which is mainly arsenic trifluoride, AsF_{3}, but which appears also to contain a new fluoride, the pentafluoride, AsF_{5}, inasmuch as the solution in water yields the reactions of both arsenious and arsenic acids.

_Carbon._--Chlorine does not unite with carbon even at the high temperature of the electric arc, but fluorine reacts even at the ordinary temperature with finely divided carbon. Purified lampblack inflames instantly with great brilliancy, as do also the lighter varieties of wood charcoal. A curious phenomenon is noticed with wood charcoal; it appears at first to absorb and condense the fluorine, then quite suddenly it bursts into flame with bright scintillations. The denser varieties of charcoal require warming to 50 deg. or 60 deg. before they inflame, but it once the combustion is started at any point it rapidly propagates itself throughout the entire piece. Graphite must be heated to just below dull redness in order to effect combination; while the diamond has not yet been attacked by fluorine, even at the temperature of the Bunsen flame. A mixture of gaseous fluorides of carbon are produced whenever carbon of any variety is acted upon by fluorine, the predominating constituent being the tetrafluoride, CF_{4}.

_Boron._--The amorphous variety of boron inflames instantly in fluorine, with projection of brilliant sparks and liberation of dense fumes of boron trifluoride, BF_{3}. The adamantine modification behaves similarly if powdered. When the experiment is performed in the fluorspar tube, the gaseous fluoride may be collected over mercury. The gas fumes strongly in the air, and is instantly decomposed by water.

_Silicon._--The reaction between fluorine and silicon is one of the most beautiful of all these extraordinary manifestations of chemical activity. The cold crystals become immediately white-hot, and the silicon burns with a very hot flame, scattering showers of star-like, white-hot particles in all directions. If the action is stopped before all the silicon is consumed, the residue is found to be fused. As crystalline silicon only melts at a temperature superior to 1,200 deg., the heat evolved must be very great. If the reaction is performed in the fluorspar tube, the resulting gaseous silicon tetrafluoride, SiF_{4}, may be collected over mercury.

Amorphous silicon likewise burns with great energy in fluorine.

ACTION OF FLUORINE UPON METALS.

_Sodium_ and _potassium_ combine with fluorine with great vigor at ordinary temperatures, becoming incandescent, and forming their respective fluorides, which may be obtained crystallized from water in cubes. Metallic _calcium_ also burns in fluorine gas, forming the fused fluoride, and occasionally minute crystals of fluorspar. _Thallium_ is rapidly converted to fluoride at ordinary temperatures, the temperature rising until the metal melts and finally becomes red hot. Powdered _magnesium_ burns with great brilliancy. _Iron_, reduced by hydrogen, combines in the cold with immediate incandescence, and formation of an anhydrous, readily soluble, white fluoride. _Aluminum_, on heating to low redness, gives a very beautiful luminosity, as do also _chromium_ and _manganese_. The combustion of slightly warmed zinc in fluorine is particularly pretty as an experiment, the flame being of a most dazzling whiteness. _Antimony_ takes fire at the ordinary temperature, and forms a solid white fluoride. _Lead_ and _mercury_ are attacked in the cold, as previously described, the latter with great rapidity. _Copper_ reacts at low redness, but in a strangely feeble manner, and the white fumes formed appear to combine with a further quantity of fluorine to form a perfluoride. The main product is a volatile white fluoride. _Silver_ is only slowly attacked in the cold. When heated, however, to 100 deg., the metal commences to be covered with a yellow coat of anhydrous fluoride, and on heating to low redness combination occurs, with incandescence, and the resulting fluoride becomes fused, and afterward presents a satin-like aspect. _Gold_ becomes converted into a yellow deliquescent volatile fluoride when heated to low redness, and at a slightly higher temperature the fluoride is dissociated into metallic gold and fluorine gas.

The action of fluorine on _platinum_ has been studied with special care. It is evident, in view of the corrosion of the positive platinum terminal of the electrolysis apparatus, that nascent fluorine rapidly attacks platinum at a temperature of -23 deg.. At 100 deg., however, fluorine gas appears to be without action on platinum. At 500 deg.-600 deg. it is attacked strongly, with formation of the tetrafluoride. PtF_{4}, and a small quantity of the protofluoride, PtF_{2}. If the fluorine is admixed with vapor of hydrofluoric acid, the reaction is much more vigorous, as if a fluorhydrate of the tetrafluoride, perhaps 2HF.PtF_{4}, were formed. The tetrafluoride is generally found in the form of deep-red fused masses, or small yellow crystals resembling those of anhydrous platinum chloride. The salt is volatile and very hygroscopic. Its behavior with water is peculiar. With a small quantity of water a brownish yellow solution is formed, which, however, in a very short time becomes warm and the fluoride decomposes; platinic hydrate is precipitated, and free hydrofluoric acid remains in solution. If the quantity of water is greater, the solution may be preserved for some minutes without decomposition. If the liquid is boiled, it decomposes instantly. At a red heat platinic fluoride decomposes into metallic platinum and fluorine, which is evolved in the free state. This reaction can therefore be employed as a ready means of preparing fluorine, the fluoride only requiring to be heated rapidly to redness in a platinum tube closed at one end, when crystallized silicon held at the open end will be found to immediately take fire in the escaping fluorine. The best mode of obtaining the fluoride of platinum for this purpose is to heat a bundle of platinum wires to low redness in the fluorspar reaction tube in a rapid stream of fluorine. As soon as sufficient fluoride is formed on the wires, they are transferred to a well stoppered dry glass tube, until required for the preparation of fluorine.

ACTION OF FLUORINE UPON NON-METALLIC COMPOUNDS.

_Sulphureted Hydrogen._--When the horizontal tube shown in Fig. 3 is filled with sulphureted hydrogen gas and fluorine is allowed to enter, a blue flame is observed on looking through the fluorspar windows playing around the spot where the fluorine is being admitted. The decomposition continues until the whole of the hydrogen sulphide is converted into gaseous fluorides of hydrogen and sulphur.

_Sulphur dioxide_ is likewise decomposed in the cold, with production of a yellow flame and formation of fluoride of sulphur.

_Hydrochloric acid_ gas is also decomposed at ordinary temperatures with flame, and, if there is not a large excess of hydrochloric acid present, with detonation. Hydrofluoric acid and free chlorine are the products.

Gaseous _hydrobromic_ and _hydriodic acids_ react with fluorine in a similar manner, with production of flame and formation of hydrofluoric acid. Inasmuch, however, as bromine and iodine combine with fluorine, as previously described, these halogens do not escape, but burn up to their respective fluorides. When fluorine is delivered into an aqueous solution of hydriodic acid, each bubble as it enters produces a flash of flame, and if the fluorine is being evolved fairly rapidly there is a series of very violent detonations. A curious reaction also occurs when fluorine is similarly passed into a 50 per cent. aqueous solution of hydrofluoric acid itself, a flame being produced in the middle of the liquid, accompanied by a series of detonations.

_Nitric acid_ vapor reacts with great violence with fluorine, a loud explosion resulting. If fluorine is passed into the ordinary liquid acid, each bubble as it enters produces a flame in the liquid.

_Ammonia gas_ is decomposed by fluorine with formation of a yellow flame, forming hydrofluoric acid and liberating nitrogen. With a solution of the gas in water, each bubble of fluorine produces an explosion and flame, as in case of hydriodic acid.

_Phosphoric anhydride_, when heated to low redness, burns with a pale flame in fluorine, forming a gaseous mixture of fluorides and oxyfluoride of phosphorus. _Pentachloride and trichloride of phosphorus_ both react most energetically with fluorine, instantly producing a brilliant flame, and evolving a mixture of phosphorus pentafluoride and free chlorine.

_Arsenious anhydride_ also affords a brilliant combustion, forming the liquid trifluoride of arsenic, AsF_{3}. This liquid in turn appears to react with more fluorine with considerable evolution of heat, probably forming the pentafluoride, AsF_{5}. _Chloride of arsenic_, AsCl_{3}, is converted with considerable energy to the trifluoride, free chlorine being liberated.

_Carbon bisulphide_ inflames in the cold in contact with fluorine, and if the fluorine is led into the midst of the liquid a similar production of flame occurs under the surface of the liquid, as in case of nitric acid. No carbon is deposited, both the carbon and sulphur being entirely converted into gaseous fluorides.

_Carbon tetrachloride_, as previously mentioned, reacts only very slowly with fluorine. The liquid may be saturated with gaseous fluorine at 15 deg., but on boiling this liquid a gaseous mixture is evolved, one constituent of which is carbon tetrafluoride, CF_{4}, a gas readily capable of absorption by alcoholic potash. The remainder consists of another fluoride of carbon, incapable of absorption by potash and chlorine. A mixture of the vapors of carbon tetrachloride and fluorine inflames spontaneously with detonation, and chlorine is liberated without deposition of carbon.

_Boric anhydride_ is raised to a most vivid incandescence by fluorine, the experiment being rendered very beautiful by the abundant white fumes of the trifluoride which are liberated.

_Silicon dioxide_, one of the most inert of substances at the ordinary temperature, takes fire in the cold in contact with fluorine, becoming instantly white-hot, and rapidly disappearing in the form of silicon tetrafluoride. The _chlorides_ of both _boron_ and _silicon_ are decomposed by fluorine, with formation of fluorides and liberation of chlorine, the reaction being accompanied by the production of flame.

ACTION OF FLUORINE UPON METALLIC COMPOUNDS.

_Chlorides_ of the metals are instantly decomposed by fluorine, generally at the ordinary temperature, and in certain cases, antimony trichloride for instance, with the appearance of flame. Chlorine is in each case liberated, and a fluoride of the metal formed. A few require heating, when a similar decomposition occurs, often accompanied by incandescence, as in case of chromium sesquichloride.

_Bromides_ and _iodides_ are decomposed with even greater energy, and the liberated bromine and iodine burn in the fluorine with formation of their respective fluorides.

_Cyanides_ react in a most beautiful manner with fluorine, the displaced cyanogen burning with a purple flame. Potassium ferrocyanide in particular affords a very pretty experiment, and reacts in the cold. Ordinary potassium cyanide requires slightly warming in order to start the combustion.

Fused _potash_ yields potassium fluoride and ozone. Aqueous potash does not form potassium hypofluorite when fluorine is bubbled into it, but only potassium fluoride. _Lime_ becomes most brilliantly incandescent, owing partly to the excess being raised to a very high temperature by the heat developed during the decomposition, and partly to the phosphorescence of the calcium fluoride formed.

_Sulphides_ of the alkalies and alkaline earths are also immediately rendered incandescent, fluorides of the metal and sulphur being respectively formed.

_Boron nitride_ behaves in an exceedingly beautiful manner, being attacked in the cold, and emitting a brilliant blue light which is surrounded by a halo of the fumes of boron fluoride.

_Sulphates_, _nitrates_ and _phosphates_ generally require the application of more or less heat, when they too are rapidly and energetically decomposed. Calcium phosphate is attacked in the cold like lime, giving out a brilliant white light, and producing calcium fluoride and gaseous oxyfluoride of phosphorus, POF_{3}. _Calcium carbonate_ also becomes raised to brilliant incandescence when exposed to fluorine gas, as does also normal _sodium carbonate_; but curiously enough the bicarbonates of the alkalies do not react with fluorine even at red heat. Perhaps this may be explained by the fact that fluorine has no action at available temperatures upon carbon dioxide.

ACTION OF FLUORINE UPON A FEW ORGANIC COMPOUNDS.

_Chloroform._--When chloroform is saturated with fluorine, and subsequently boiled, carbon tetrafluoride, hydrofluoric acid and chlorine are evolved. If a drop of chloroform is agitated in a glass tube with excess of fluorine, a violent explosion suddenly occurs, accompanied by a flash of flame, and the tube is shattered to pieces. The reaction is very lively when fluorine is evolved in the midst of a quantity of chloroform, a persistent flame burns beneath the surface of the liquid, carbon is deposited, and fluorides of hydrogen and carbon are evolved together with chlorine.

_Methyl chloride_ is decomposed by fluorine, even at -23 deg., with production of a yellow flame, deposition of carbon, and liberation of fluorides of hydrogen and carbon and free chlorine. With the vapor of methyl chloride, as pointed out in the description of the electrolysis, violent explosions occur.

_Ethyl alcohol_ vapor at once takes fire in fluorine gas, and the liquid is decomposed with explosive violence without deposition of carbon. Aldehyde is formed to a considerable extent during the reaction.

_Acetic acid_ and _benzene_ are both decomposed with violence, their cold vapors burn in fluorine, and when the latter is bubbled through the liquids themselves, flashes of flame, and often most dangerous explosions, occur. In the case of benzene, carbon is deposited, and with both liquids fluorides of hydrogen and carbon are evolved. _Aniline_ likewise takes fire in fluorine, and deposits a large quantity of carbon, which, however, if the fluorine is in excess, burns away completely to carbon tetrafluoride.

Such are the main outlines of these later researches of M. Moissan, and they cannot fail to impress those who read them with the prodigious nature of the forces associated with those minutest of entities, the chemical atoms, as exhibited at their maximum, in so far as our knowledge at present goes, in the case of the element fluorine.--_Nature._

* * * * *

APPARATUS FOR THE ESTIMATION OF FAT IN MILK.

By E. MOLISABI.

The author, after criticising the various methods for estimating fat in milk which have been proposed from time to time, agrees with Stokes (_Analyst_, 1885, p. 48), Eustace Hill (_Analyst_, 1891, p. 67), and Bondzynsky (_Landwirth Jahrb. der Schweiz_, 1889), that the method of Werner Schmid is the simplest, most rapid, and convenient hitherto introduced. The conditions tending to inaccuracy are: The employment of ether containing alcohol; boiling the mixture of milk and acid too long, when a caramel-like body is formed, soluble in ether; the difficulty of reading off the volume of ether left in the tube, owing to the gradations of the instrument being obscured by the flocculent layer of casein; when only a portion of the ether is used, fat may be left behind in the acid mixture, as shown by Allen (_Chem. Zeit._, 1891, p. 331). The author believes that by the invention of the simple apparatus represented in the accompanying figure, he has rendered the process both accurate and convenient. This consists of a flask B of about 75 c.c. capacity, which has a glass tap fused on, with two capillary tubes attached, the one passing upward, the other downward. The neck of flask B is ground into the neck of flask A, which holds about 90 c.c. Either of the flasks can be placed in communication with the external air by the opening _a_. The ether must be previously washed with one or two tenths of its volume of water, to remove traces of alcohol. The operation is performed as follows: 10 c.c. of well mixed milk are weighed in (or measured into) flask A, 10 c.c. of hydrochloric acid added, and the mixture heated to boiling on an asbestos sheet. The boiling must not exceed a minute and a half, the fluid being shaken from time to time, and not allowed to become of a deeper color than a dark brown [not black]. The flask is cooled, and 25 c.c. of ether added. The two flasks are connected as shown in the figure, the tap closed, and the whole shaken for a few minutes, the flask being vented two or three times by the opening _a_. The apparatus is now inverted, allowed to stand five or six minutes, the tap turned, and the dark acid liquid drawn off into flask B. By a little shaking of the ether the whole of the acid liquid may be easily got into the lower flask. The apparatus is again inverted, then separated, 10 c.c. of ether are introduced into the flask B, the tap closed, and the fluids well shaken. When the ether layer is distinct, the acid liquor is run off, and the ether solution transferred to A. The whole of the ether solution is washed in the apparatus two or three times with a little water, the flask A removed to the water bath, the ether driven off, the last traces of ether and water being removed by placing the flask in a drying oven heated from 107 to 110 deg. C., where it must remain at least twenty minutes. The usual cooling in the exsiccator and weighing concludes the operation. Examples are given showing its concordance with the Adams and other recognized processes. Sour milk, which must be weighed in the flask, can be conveniently analyzed; also cream, using 5 grammes cream and 10 c.c. hydrochloric acid. (_Berichte Deutsch. Chem. Gesell._, 24, p. 2204).--_The Analyst._

* * * * *

AMERICAN ASSOCIATION--NINTH ANNUAL REPORT OF THE COMMITTEE ON INDEXING CHEMICAL LITERATURE.[1]

[Footnote 1: From advance proof sheets of the Proceedings of the
American Association for the Advancement of Science; Washington
meeting, 1891.]

The Committee on Indexing Chemical Literature respectfully presents to the Chemical Section its ninth annual report.

Since our last meeting the following bibliographies have been printed:

1. A Bibliography of Geometrical Isomerism. Accompanying an address on this subject to the Chemical Section of the American Association for the Advancement of Science at Indianapolis, August, 1890, by Professor Robert B. Warder, Vice President. Proceedings A.A.A.S., vol. xxxix. Salem, 1890. 8vo.

2. A Bibliography of the Chemical Influence of Light, by Alfred Tuckerman. Smithsonian Miscellaneous Collections No. 785. Washington, D.C., 1891. Pp. 22. 8vo.

3. A Bibliography of Analytical Chemistry for the year 1890, by H. Carrington Bolton. J. Anal. Appl. Chem., v., No. 3. March, 1891.

We chronicle the publication of the following important bibliography:

4. A Guide to the Literature of Sugar. A book of reference for chemists, botanists, librarians, manufacturers and planters, with comprehensive subject index. By H. Ling Roth. London: Kegan Paul, Trench, Trubner & Co. Limited. 1890. 8vo. Pp xvi-159.

This work contains more than 1,200 titles of books, pamphlets, and papers relating to sugar. Many of the titles are supplemented with brief abstracts. The alphabetical author catalogue is followed by a chronological table and an analytical subject index. The compilation extends to the beginning of the year 1885, and the author promises a supplement and possibly an annual guide.

The ambitious work is useful but very incomplete. It does not include glucose. The author gives a list of fifteen periodicals devoted to sugar, and omits exactly fifteen more recorded in Bolton's _Catalogue of Scientific and Technical Periodicals_ (1665-1882). Angelo Sala's _Saccharologia_ is not named, though mentioned in Roscoe and Schorlemmer and elsewhere.

Notwithstanding some blemishes, this work is indispensable to chemists desirous of becoming familiar with the literature of sugar. It is to be hoped that a second edition brought down to date may be issued by the author.

5. A Bibliography of Ptomaines accompanies Professor Victor C. Vaughan's work, Ptomaines and Leucomaines. Philadelphia, 1888. (Pages 296-814.) 8vo.

Chemists will hail with pleasure the announcement that a new dictionary of solubilities is in progress by a competent hand. Professor Arthur M. Comey, of Tufts College, College Hill, Mass., writes that the work he has undertaken will be as complete as possible. "The very old matter which forms so large a part of Storer's Dictionary will be referred to, and in important cases fully given. Abbreviations will be freely used and formulae will be given instead of the chemical names of substances, in the body of the book. This is found to be absolutely necessary in order to bring the work into a convenient size for use ..., The arrangement will be strictly alphabetical. References to original papers will be given in all cases ..."

Professor Comey estimates his work will contain over 70,000 entries, and will make a volume of 1,500-1,700 pages.

The following letter from Mr. Howard L. Prince, Librarian of the United States Patent Office, explains itself:

WASHINGTON, D.C., February 11, 1891

_Dr. H Carrington Bolton._
_University Club, New York, N.Y._:

DEAR SIR--In response to your request I take pleasure in
giving you the following information regarding the past
accomplishments and plans for the future of the Scientific
Library in the matter of technological indexing.

The work of indexing periodicals has been carried on in the
library for some years in a somewhat desultory fashion, taking
up one journal after another, the object being, apparently, more
to supply clerks with work than the pursuance of any well
defined plan. However, one important work has been substantially
completed, viz., a general index to the whole set of the
SCIENTIFIC AMERICAN and SUPPLEMENT from 1846 to date.

It is unnecessary for me to point out to you the importance of
this work, embracing a collection which has held the leading
place in the line of general information on invention and
progress, the labor of compiling which has been so formidable
that no movement in that direction has been attempted by the
publishers except in regard to the SUPPLEMENT only, and that
very imperfectly. This index embraces now 184,600 cards, not
punched, and at present stored in shallow drawers and fastened
by rubber bands, and of course they are at present unavailable
for use. There is little prospect of printing this index, and
I have been endeavoring for some time to throw the index open
to the public by punching the cards and fastening them with
guard rods, but as yet have made no perceptible impression
upon the authorities, although the expense of preparation
would be only about $70.

There has also been completed an index to the English journal
_Engineering_, comprising 84,000 cards, from the beginning to
date.

An index to Dingler's _Polytechnisches Journal_ was also
commenced as long ago as 1878, carried on for six or seven
years and then dropped. I hope, however, at no remote date, to
bring this forward to the present time.

On taking charge of the library I was at once impressed with
the immense value of the periodical literature on our shelves
and the great importance of making it more readily accessible,
and have had in contemplation for some time the beginning of a
card index to all our periodicals on the same general plan as
that of Rieth's Repertorium. I have, however, been unable to
obtain sufficient force to cover the whole ground, but have
selected about one hundred and fifty journals, notably those
upon the subjects of chemistry, electricity and engineering,
both in English and foreign languages, the indexing of which
has been in progress since the first of January. This number
includes substantially all the valuable material in our
possession in the English language, not only journals, but
transactions of societies, all the electrical journals and
nearly all the chemical in foreign languages. This index will
be kept open to the public as soon as sufficient material has
accumulated. In general plan it will be alphabetical,
following nearly the arrangement of the periodical portion of
the surgeon general's catalogue. I shall depart from the
strictly alphabetical plan sufficiently to group under such
important subjects as chemistry, electricity, engineering,
railroads, etc., all the subdivisions of the art, so that the
electrical investigator, for instance, will not be obliged to
travel from one end of the alphabet to the other to find the
divisions of generators, conductors, dynamos, telephones,
telegraphs, etc., and in the grouping of the classes of
applied science the office classification of inventions will,
as a rule, be adhered to, the subdivisions being, of course,
arranged in alphabetical order under their general head and
the title of the several articles also arranged alphabetically
by authors or principal words.

With many thanks for the kind interest and valuable
information afforded me, I remain, very truly yours,

HOWARD L. PRINCE,
Librarian Scientific Library.