Sirmium

“ Fused nitrate of silver is in small cylinders of a dark grey colour, and presenting, when broken across, a crystalline structure. Odour, none; Taste, intensely bitter, austere and metallic; it tinges the skin indelibly black; when perfectly free from copper, it is not deliquescent. Chemical Composition; oxide of silver 70, nitric acid 30, or one atom of oxide and one atom of acid. Solubility. In an equal weight of water, at 60°; it is also soluble in alcohol. The solution readily yields transparent colourless crystals, the primary form of which is a right rhombic prism. ”

“ The powdery metal burns readily in air, the crystalline metal requires to be heated in an oxyhydrogen flame before it catches fire. Mineral acids generally attack the crystallized metal very little even in the heat; aqua regia, however, dissolves it readily, and so does hydrofluoric acid. In its chemical affinities zirconium resembles titanium, cerium and thorium; it occurs in company with these elements, and is tetravalent in its more important salts.
Zirconium oxide or zirconia, ZrO2, has become important since its application to the manufacture of mantles for incandescent gas-lighting. ”

“ The Assay of Silver Ores.
A large proportion of the silver of commerce is extracted from ores (which are too poor to allow of their being smelted or fused) by a process called amalgamation. Founded on the ready solubility of silver, &c., in metallic mercury, the ore is first crushed to powder, then mixed with common salt, and afterwards roasted. By the adoption of this plan the silver is reduced to a state of chloride. The roasting is done in a reverberatory furnace, in which the heat is very gradually raised, the ore being constantly stirred ”

“ Wherever the fluids of the living body can penetrate, there also mineral substances can be carried, and this natural injection, effected under great pressure and with the advantage of ample time, can surpass any of the feats of the anatomical manipulator. Fig. 25 represents a microscopic joint of a Crinoid from the Upper Silurian of New Brunswick, injected with the hydrous silicate already referred to, and fig. 26 shows a microscopic « 105 » chambered or spiral shell, from a Welsh Silurian limestone, with its cavities filled with a similar substance. ”

“ Zirconium is always, with the doubtful exception of its peroxy-compounds and the lower oxides, tetravalent. Cerium, as already described, can form two series of compounds, in which it is respectively tri- and tetravalent; thorium, like zirconium, is always tetravalent.
Titanium, Ti = 48·1
Though generally classed among the rare elements, titanium is probably at least as widely distributed in nature as most of the common metals. It occurs as the dioxide in small quantities in all the common silicate rocks and minerals, and in traces in the animal and vegetable kingdoms ”

“ Silver ore may be detected by dissolving a small quantity in a test tube with a few drops of nitric acid. Boil until all the red fumes disappear. Let the solution cool, and add a little water. Filter the whole, and add a few drops of muriatic acid, which will precipitate the white chloride of silver. Dissolve this precipitate with ammonia; then add nitric acid once more. Exposed to the light, the precipitate soon shows a violet tint. Pure silver is the brightest of metals, of a brilliant white hue, with rich luster. ”

“ It occurs in some silicates, and in small quantities in almost all the rare earth minerals. The most important source of the element and its compounds was until quite recently the mineral Zircon, with its gem-varieties Hyacinth and Jargon, and the large number of secondary altered zircon minerals. Since its discovery in 1892, however, the naturally occurring oxide, Baddeleyite, [455] has become increasingly important for the extraction of zirconium compounds, especially for the preparation of the pure oxide for fire-resistant materials. ”

“ The minerals may be treated by any of the usual methods. Zircon may be fused with alkali or alkali carbonate; the cooled melt is extracted with water, and the insoluble alkali zirconate decomposed by dilute acids; from the solution, zirconia is thrown down by alkalies. Potassium hydrogen fluoride and potassium hydrogen sulphate may be used for the treatment either of zircon or of baddeleyite; in the first case, the potassium fluozirconate formed may be dissolved by boiling with dilute hydrofluoric acid, and separates out readily on cooling, whilst the fluosilicate formed is not dissolved ”

“ The sistrum consists of a metal frame in the shape of an egg, fastened to a handle, frequently surmounted by a grotesque head or by a figure of the sacred lioness Sekhet. The frame is crossed by four metal horizontal rods passing through holes large enough to allow them to rattle when the sistrum is shaken, the rods being prevented from slipping out altogether by little metal stops in the shape of a leaf; sometimes metal rings are threaded over the rods to increase the jingling. The sistrum is played also by beating it with a metal stick. ”

“ And although the simpler kinds are obviously formed of threads, most of the more compound may also be resolved into the same structure by maceration in hot water or diluted muriatic acid. In substance some are mere masses of slime or jelly, others are silky to the feel, horny, cartilaginous or leather-like, and even apparently woody. A few species secrete carbonate of lime from the water, laying it up in their tissues; others cover themselves completely with that mineral, while some coat themselves with silex or flint. ”

“ Siderite effervesces with strong acid; and this separates it from all other rocks, except limestone and dolomite; and from these it is distinguished by its high specific gravity. As a mineral, siderite is often light colored; but as a rock it is always dark, and usually black, from admixture chiefly of carbonaceous matter. In studying dynamical geology, we have learned (page 28) the reason for the intimate association of siderite with beds of coal, and this accounts equally for the carbon contained in the rock itself. ”

“ Zircon is a silicate of zirconium, ZrSiO4, with small quantities of other elements. Most varieties contain ferric oxide and thoria; more rarely small proportions of the yttria earths may be present. All varieties contain traces of a large number of the common metals. Traces of radium are usually present, with helium and neon, [50] and the mineral is strongly radioactive. ”

“ We have already seen in Ibn Sina that the metals consist of the combination of sulphur and mercury. Even earlier the interaction of two parts were figuratively called impregnation. Both fuse into one symbol, and indeed so much the more readily, as it probably arose as the result of analogous thoughts, determined by a sexual complex. Also there occurs the idea that we must derive a male activity from the gold, a female from the silver, in order to get from their union that which perfects the mercury of the metals. ”

“ If an organic substance be used to form a paste with metallic zirconium, the final process of heating results in the formation of the carbide; the same compound is also obtained by another process protected by Sander (loc. cit.) in which the hydride of zirconium, prepared by the reduction of the oxide by means of powdered magnesium in an atmosphere of hydrogen, is mixed with a cellulose solution, and the liquid treated as in the manufacture of artificial silk, the threads obtained being then heated to remove all organic matter as far as possible. ”

“ Dry the residue and concentrate the silver in a button of lead by pot method or scorification, according to the amount of stony matter present. Cupel the lead, and the resulting button will be free from all metals, except perhaps gold. It may be weighed; or dissolved in nitric acid, and the silver determined gravimetrically in the diluted and filtered solution. It is better to weigh the metal and afterwards to determine the gold in it, estimating the silver by difference. Silver alloys are dissolved in dilute nitric acid (free from chlorides) , diluted, and filtered. ”

“ A plain silver solution, of a strength of 30 grains of nitrate of silver to the ounce of water in hot weather, increasing to 60 grains in the coldest, with enough bi-carbonate of soda added from time to time to keep a small sediment of carbonate of silver in the bottom of p73 the bottle or dish, is all that can be desired as a silvering solution for albumen paper. It only needs to be kept up to the proper strength by the addition of silver nitrate and water, when required ”

“ When heated in a current of hydrogen at a red heat, it forms the hydride, ZrH2, [462] as a velvet-black powder, which burns with an intense bluish flame in oxygen, forming the sesquioxide, Zr2O3. When heated in nitrogen or ammonia, amorphous zirconium yields nitrides, which are also obtained when any attempt is made to reduce zirconium compounds to the metal in air. The most definite is the compound Zr2N3, [462] which forms a bronze-coloured powder, resistant to all mineral acids except hydrofluoric acid. Chlorine and bromine transform this to the halide. ”

“ Thorium and titanium accompany the zirconium, but iron, aluminium, and the rare earths remain in solution. Another method depends on the fact that zirconium is not precipitated from alkaline solution by ammonium sulphide in the presence of tartaric acid, whereas this reagent does not inhibit the precipitation of ferrous sulphide. Iron may also be removed from a solution in concentrated hydrochloric acid by means of ether, in which medium ferric chloride is easily soluble. Zirconium compounds may be obtained free from iron by repeated crystallisations of the oxychloride. ”

“ Ibn Sina had taught that two principles entered into the constitution of metals. Mercury is the bearer of the metallic property and sulphur has the nature of the combustible and is the cause of the transmutation of metals in fire. The doctrine of the two principles leads to the theory that for the production of gold it was necessary to get from metals the purest possible sulphur and mercury, in order to produce gold by the union of both. Paracelsus now adds to the two principles a third, salt, as the element of fixedness or palpability, as he terms it. ”

“ Thus the attraction between oxygen and silver is so slight that at a comparatively low temperature the oxide of silver is decomposed. In like manner, limestone, or carbonate of lime, is decomposed when subjected to the heat of a lime-kiln, carbonic acid being given off, while quick-lime remains behind. Now, in separating heterogeneous [Pg 59] atoms against the powerful force of chemical affinity, work is done as truly as it is in separating molecules from one another against the force of cohesion, or in separating a stone from the earth against the force of gravity. ”

“ The siderite is formed where decaying vegetation is present to furnish abundant carbon dioxide and to partially protect the iron solution from oxidation, and the limonite where free oxidation takes place. Sand, silt, clay, or calcium carbonate often accumulates with the iron precipitate, and the result is an impure deposit which becomes an ironstone. Such deposits often become segregated into nodules, as will be explained later. It is thought that diatoms sometimes aid in the deposit of iron ore in shallow waters. ”

“ The mere touch of a hard substance will sometimes explode it; and its very preparation is so hazardous that this ought never to be attempted without a mask upon the face with strong glass eyes.
The following are three pleasing experiments with preparations of silver:
1. Mix or amalgamate together four parts of silver leaf with two parts of mercury (228) and dissolve this in diluted aqua fortis. To the solution add as much water as will be equal to thirty times the weight of the metals employed. Pour a portion of the above mixture into a phial, and place at the bottom a small piece of silver. ”

“ Such was the opposition encountered, and such was the timidity of his professional brethren, that but for Simpson’s courageous efforts it would have been the work of years to bring about what it was granted to him to accomplish in a brief period; if fear, ridicule, contempt, and bigotry had not perhaps sunk the new practice into oblivion. Of the hundreds who are daily mercifully brought under the influence of chloroform and ether, few are aware what they owe to Simpson, even if they know how great is the suffering which they are spared. ”

“ The silvering of glass is based on the fact that silver which is reduced from certain solutions deposits itself uniformly in a perfectly homogeneous and continuous but very thin layer, forming a bright reflecting surface. Certain organic substances have the property of reducing silver in this form. The best known among these are certain aldehydes—for instance, ordinary acetaldehyde, C2H4O, which easily oxidises in the air and forms acetic acid, C2H4O2. This oxidation also easily takes place at the expense of silver oxide, when a certain amount of ammonia is added to the mixture. ”

“ The burning of the lemel has a great tendency to destroy all organic matter that would be likely to cause the mixture to overflow during the period of fusion; but if such a thing should be at all likely to take place, the addition of a little dried common salt would remedy the evil, a small quantity of which ought always to be provided for the purpose. The common carbonate of soda is also a cheap and useful flux to the silversmith. ”