Scientific American 5, 30.1.1869
By Dr. L. Feuchtwanger.
This mineral substance was known in ancient times under the name of "glassmaker's sopa" and was consideres a species of iron ore. In the year 1740 it was ascertained to be an oxide of a separate metal, and in 1774, Gahn obtained the pure metal from the native carbonate, exposing the same to intense heat for several hours, or by subjecting chloride of manganese to electrolysis. Boerhaave does not appear to have known the metal. In my English edition of 1753 he speaks of it in the following words: "Take the frit and set it in the melting pots in a working furnace, adding in each pot a proper quantity of a blackish stone not unlike loadstone, and called manganese, which servesto purge off that greenish cast natural to all glass and to make it clear." Scheele, Bergman, Chevreul, Berthler, and Berzelius, have in modern times investigated the physical and chemical characters of manganese. The ore is widely distributed over our globe; it accompanies many iron ores, particularly the hematites, also the franklinite of New Jersey. It has been detected as a constituent of meteoric iron in the ashes of most vegetable and many animal substances, is the coloring principle of many fossils in a dendirtic form in the chalcodony which is called the "mocha stone," and in the same form on sand pebbles of which I found plenty in Stanislaus River in California. It also occurs combined with sulphur, carbonic acid, silica, water, and with many atomic proportions of oxygen, such as protoxide, sesquioxide, binoxide, manganic acid, and permanganic acid becoming thereby sometimes a base and sometimes an acid. The principal varieties of manganese found in nature are of the following descriptions:
1st. Hausmannite has the form of a four-sided pyramidal crystal, with hardness 5, and a specific gravity 4·7.
2d. Braunite is an anhydrous sesquioxide, crystallizes in an octahedron, is much harder than the last, and has a higher specific gravity.
3d. Psilomelane, generally called the compact gray oxide, occurs in botryoidal and stalactitic shapes.
4th. Manganite is a hydrous sesquioxide; crystallizes in right rhombic prisms.
5th. Pyrolusite, the most useful and abundant ore of manganese, derives its name from two Greek words signifying "fire" and "to wash", in allusion to its property of discharging the brown and green tints of glass; it crystallizes in small retangular prisms, or is fibrous, radiated, and divergent, of iron black color and grayish streak, has a specific gravity of 4·94, and is composed of 37 per cent oxygen and 63 per cent manganese. This ore is generally called binoxide, deutoxide, or peroxide, is a good conductor of electricity, and strongly electro-negative in the voltaic circuit. When heated to redness it readily parts with its excess of oxygen as it gives off one third of it. When heated with sulphuric acid one half of its oxygen escapes. Owing to this property it is more employed in the arts than any other oxide; it is called in trade the "black oxide of manganese." Its commercial value is dependant upon the proportion of oxygen which it contains in excess of that which is necessary to its existence as sesquioxide. A convenient method of estimating this excess of oxygen is founded upon the circumstance, that the black oxide of manganese is decomposed in the presence of oxalic acid, and from sulphuric acid proto-sulphate of manganese is formed, and all the excess of oxygen reacts upon the oxalic acid and converts it into carbonic acid which passess off with effervescence. If the micture be weighed before the decomposition has been effected, and again after it has been completed, the loss will indicate the amount of carbonic acid; each equivalent of peroxide of manganese gives two equivalents or its own weight of carbonic acid.
Manganic acid is known under the name of chameleon mineral, is obtained artificially by fusing the peroxide of manganese with equal weights of caustic potash, which when dissolved in a small quantity of water has a green color, but when largely diluted becomes purple and ultimately claret color; for this property it has been employed for many years in the arts.
Permanganic acid is artificially obtained by mixing intimately four parts of finely powdered peroxide of manganese with three and one half of parts of chlorate of potash, while five parts of hydrate of potash are dissolved in a small quantity of water and added tot he above mixture, the whole is evaporated and reduced to powder, then theated to dull redness for an hour in an earchen crucible and when cold the mass is treated with water and filtered through a funnel plugged with asbestor; the solution after being neutralized with sulphuric acid yields on evaporation beautiful red acicular crystals of permanganate of potash. This preparation of later years has become an important vehicle for disinfection. Among the other native oxides of manganese may be mentioned the mineral wad which is also very abundant but not valuable enough to produce gas. It is amorphous, solft, black, or brown and purple; when mized with linseed oil it produces spontaneous combustion. It is supposed to be the coloring ingredient of the dedritic delineations upon many substances, such a steatite and others mentioned elsewhere. The localities of manganese are very prolific; pyrolusite has been mined very extensively in Europe; psilomelan in England, France, Belgium, and the United States; manganite in Bohemia, Saxony, and England. Much of the latter is consumed in the bleacheries of those countries. The United States and the Provinces have inexhaustible deposits of the oxides of manganese. From Vermont, the eastern limit, to Georgia, the southern limit, large supplies were formerly furnished, but in late years West Virginia, North Carolina, and California have supplied us to a large extent but not of a high grade of oxidation. While the binoxide of manganese suitable for the manufactures ought to yield from 80 to 90 per cent of oxygen gas, the product of the last mentioned States has not exceeded 50 to 70 percent oxygen. The provinces of New Brunswick and Nova Scotia have produced within a few years very superior oxides of manganese, and the specimens I possess in my cabinet excel in richness and beauty those from Ilmuran in Thuringen and Ihlefeld in the Hartz mountains of days gone by. The manufacturers of bleaching powders in England have for the last twenty years been supplied by the little principality of Nassau to the amount of fifty thousand tuns per annum, while the United States with all its inexhaustible resources has not exported any, and it is hoped that before long the export of manganese may prove lucrative. The quality of the Nova Scotia manganese is, according to Howe, of high per centage, some from 82·4 to 89·8 of sesquioxide, and that from Tennycape as high as 97·04. The international manganese mine of New Brunswick contains from 80 to 85 per cent of sesquioxide. We find manganese in the State of Missouri containing much cobalt, while the Vermont manganese is associated with much iron. We also find in California, in the red hill of the bay facing the city of San Francisco, containing millions of tuns of psilomelane or compact manganese yielding from 40 to 50 per cent sesquioxide. We also know manganese to be abundant in Canada. A vein of 50 to 60 feet wide is said to exist at Bachawanning Bay on Lake Superior.
The geological position of manganese is not quite accurately known. In Germany it traverses porphyry and is associated with calcspar and baryta. In Vermont, in the United States, it is found among crystalline rocks; in Canada it is accompanied by dolomite, and in Nova Scotia it exists in a gray limestone, quartzite, and conglomerite, and it unquestionably belongs to the new red sandstone formation. My manganese mines at Pembroke are situated close to the gypsum deposits, which would range them with the upper silurian system.
I will now enumerate the many useful applications in the arts.
1st. Manganese is employed for producing oxygen gas in the chemical laboratory, the material of the compound blow pipe and drummond light, for the production of alkaline manganate in order to produce a good and cheap light in combination with coal gas.
2d. Manganese is most extensively used in the manufacture of chlorine so as to prepare a bleaching liquid or powder, the consumption of which by the paper and cotton manufacturers is unlimited.
3d. Next in importance is the manganese largely employed in the green flint glass works in precipitating the iron, and when added in excess to produce an amythust color in flint glass.
4th. Steel manufacturers require manganese for producing a hard and tough product; a half pound to didty iron will have the effect.
5th. Linseed oil is rendered more siccative by the addition of manganese, and is called a patent dryer for paints and varnished.
6th. A permanent black on earthenware and pottery is obtained by exposure to heat.
7th. A black enamel used in ornaments by jewelers is likewise produced with manganese.
8th. The manufacture of permangates, a powerful disinfectant, and the main material in the new oxygen light is obtained from the same.
9th. The quality of spirits, with or without distillation, is obtained by the use of ma[n]ganese.
10th. The chameleon mineral used in sugar refining is prepared with manganese.
The consumption of manganese for the manufacture of the new gas light about to be introduces in this country, forms a new epoch in this direction. It is to be converted first into the alkaline mangate, which acting as a sponge alternately absorbing the oxygen of the air and again releasing it, must require if successful, not less tan one hundred thousand tuns of manganese in order to produce a million cubic feet of oxygen gas, and I gather the following particulars from the programme issued by the inventors, Messrs. Tessle de Motay and Marechal of Metz: "The Manganates are decomposed at a temperature of 600 deg. Fah., by the action of a jet of ordinary steam which liberates the oxygen and leaves a residuum composed of sesquiozide of manganese and the alkaline base contained in the combination. The manganate is regenerated by submitting the above mentioned solid residue to the action of a current of air at the same temperature as used in the decomposition, and all these operations are conducted in a series of retorts placed in a furnace where the manganates, after being raised to a temperature of 600 deg. Fah., are alternately submitted to the action of a jet of steam and current of air which restores to the mass the oxygen has lost. The oxygen is disengaged by the steam from retorts; this steam is liquified by pressing into a condenser, and the pure oxide is collected into a gasometer. When applied for the production of light, oxygen in combination with common coal gas permits a reduction in the consumption of the latter, but at the same time giving an equal quantity of light in the proportion of 16 to 1.
The permanganate of potash of Condy's disinfectant is recommended as a powerful agent in obtaining pure drinking water and in epodemic diseases. But far the largest amount of manganese is consumed by the manufacturer of bleaching powders. England alone consumes 80,000 tuns for that purpose per annum, and as soon as the United States becomes independent of the English imported chloride of lime for bleaching the cottons and the papers, not less than one half million tuns will be consumed for the desired object, for on examining the repot of the director of the bureau of statistics, I find that 12,682 tuns of bleaching powder have been imported the first five months of the year at the value of $324,066.