TECHNICAL CHEMISTRY.

The Ores of Manganese, and their Uses, by HENRY How, D.C.L., Professor of Chemistry and Natural History, University of King's College, Windsor.

A VERY interesting, and, to all present appearances, valuable addition to the mining industry of the province has been made within the last three years by the working of the ores of manganese. Having been engaged in examining and reporting on the quality of these ores for those originally concerned, and having visited the scenes of operation, I requested and obtained permission to include such information I had gathered by these means in a general account of the manganese ores of the province at present known to me. Having been, moreover, kindly furnished with sundry details of interest from various sources, I propose now to continue, on this subject, my Notes on the Economic Mine. ralogy of Nova Scotia, of which the first part was published in the last volume of the Transactions of the Institute.

The only deposits of manganese mentioned in Dawson's Acadian Geology are an impure bed near Cornwallis Bridge, that at Musquodoboit, and those in the iron veins of Shubenacadie and in the limestones of Walton and Cheverie, of which latter it is said (p. 239):"Small quantities have been exported. I have no doubt that if the limestones can be profitably quarried on a large scale, the manganese might be separated and form

a considerable additional source of revenue; but it seems

doubtful whether mining operations for the manganese

alone can be carried on without loss."

The ores of manganese found here in quantity are Wad or bog ore; manganite, which may be called hard grey ore; and pyrolusite, which may be distinguished as soft black lustrous ore, and is often mixed with psilomelane,

a hard black ore not so lustrous as the last-named.

Wad. The first of these is a black earthy substance, which is found in rounded lumps and grains. It has been sent to me from Parrsborough, and from another locality, I believe to the east of Halifax, where it is found in lumps mixed with stones; the sample I examined contained a great deal of water, and, when dried, 56 per cent. of binoxide of 1aanganese, with the traces of cobalt which are usually found in this species. Neither of these would be valuable as ores of manganese, but they would probably serve as paints. Bog manganese is often mixed with bog iron ore, and then forms deposits of a brown or chocolate colour, called ochres or mineral paints. The paints of Bridgewater and Chester furnish examples. In the first of these I found only 11 per cent., and in the second about 20 per cent. of binoxide of manganese. It is said to be useless to send to (the English) market ores containing less than 65 per cent. binoxide.

Manganite. This is a very hard ore, which is found in compact lumps of a steel grey colour and submetallic lustre, giving a reddish-brown streak to a file. It is often found in the neighbourhood of the next mentioned; it occurs abundantly at Walton and Cheverie, and is met with at Douglas and Rawdon. At Walton I have picked it out of the stone-heaps in fields near the river, and was told that a bed of it crops out on the bank of the river near the bridge.

* Abstract from the Transactions of the Nova-Scotian Institute of Natural Science.

It is found at Cheverie in nodules on the beach about twenty rods above high-water mark, and has been dug on the upland less than two miles from the beach; it was formerly shipped, but to what extent does not appear to be known. As it is very hard, and contains in its purest form only about 49 per cent. binoxide, this ore is not useful for the ordinary applications of manganese; but I was informed by a gentleman from Boston, dealing in these ores, that it answers for a certain secret process better than the rich soft ore, and that something like fifty tons were sold in the United States in 1863, and that it was hoped the demand would increase.

Pyrolusite. This is the ordinary marketable ore, and is entirely composed of binoxide of manganese. It is so soft as to be easily scratched with a knife to a black powder, and is found in masses which are more or less glistening, and often very beautifully crystallised in black lustrous needles and prisms. It is met with near Kentville, King's County; near Pictou, Pictou County; near Amherst, Cumberland County; at Musquodoboit, Halifax County; and at Walton, and other places, especially at Teny Cape in the township of Kempt, in Hants County. These two latter are the only localities at which mining operations have been carried on, small quantities of ore having formerly been shipped from Walton, where, on one occasion, seven barrels were got out in cultivating a garden, and considerable returns, as will presently appear, having been made at Teny Cape. last-named mines was landed at Windsor in June, 1863, The first considerable collection of ore sent from the three barrels, equal to about seven and a-half tons for transmission to England. It consisted of thirtyEnglish; it was picked ore, and looked very rich and uniform in quality; the highest percentage of binoxide I know of from Teny Cape was found in a sample I put in the hands of Mr. D. Brown, a pupil of mine, who obtained 96 per cent., and when this lot of ore was sent to England it averaged, on analysis in Liverpool, 91.5 per cent. binoxide, and gave less than per cent. iron; it sold there half for 87. 10s., half for gl. sterling per ton, being disposed of to different buyers. Messrs. Tennant, of Glasgow, great consumers of manganese, are reported to have said they had never seen ore so fine.

The second mine in operation at Teny Cape was opened up by Messrs. Weeks and Co. Operations were commenced early in 1864, and during the year about eight tons (English) of ore were sent to Liverpool, where they realised 87. 58. stg. per ton. One great advantage of this locality is that the Basin of Minas is only about a mile and a-haif distant in a direct line, and the intervening country is such that a road can easily be made from the mines to the place of shipment.

Hants County possesses a variety of manganese ores in localities widely separate from each other; it has been mentioned that seven barrels of ore were on one occasion dug up in cultivating a garden at Walton; of the quality of this I know nothing, but that valuable ore is found at Walton I am certain, inasmuch as a party of which I was one extracted several pounds at a locality in the woods about seven miles from Teny Cape; one piece of this is sent to the Dublin Exhibition, and is quite as rich to all appearance as that from Teny Cape. About twelve miles south of these places Mr. Mosher has met with large detached pieces of ore; one weighing

A third mine has been opened by Messrs. Hamilton and Duvar, and a good deal of ore has been raised.

Five tons were afterwards taken out here by Mr. J. Brown.

thirty-five pounds was sent to the Exhibition of 1862 and remains in England; it consisted of pyrolusite and psilomelane; it gave to Mr. Poole, one of my pupils, about 84.5 per cent. binoxide; another large mass found in the same region weighed 184 lbs. I do not know of what kind of ore it consisted. The rock holding the manganese at Teny Cape is a limestone containing a good deal of magnesia, and coloured either grey or red by oxide of iron; it is soft, and easily detached from the ore; barytes is frequently seen crystallised through the ore, and carbonate of lime (calcite) is sometimes found beautifully crystallised in various forms encrusting the ore. At Walton the manganese is sometimes associated with iron ore (limonite), and occurs in limestone. Uses of Manganese Ores.-These ores are employed for a variety of purposes in certain manufactures of purely chemical character, or in which the aid of chemistry is necessary, and according to the application to be made of them they are required of different degrees of purity; in most cases a tolerably high percentage of the particular oxide of manganese, called the binoxide, peroxide, or available oxide, is necessary, and for certain uses there must be little clse in the ore, and especially iron must be either absent or present in extremely small proportion. The manufactures in which the ores are used are principally those of bleaching powder, glass, pottery, iron, some brown colours used in dyeing, and manganates and permanganates for certain oxidising processes (as bleaching fats) and for disinfecting. The native oxide is used for making boiled oil, and has also been recommended as a deodoriser and purifier of water, and a cheap agent for extracting gold from quartz.

It is perhaps impossible to learn the total consumption of the ore for these purposes; we know, however, that Great Britain is the great seat of the chemical manufactures, and we have some facts to guide us to an estimate of the amount used there in the processes requiring the largest quantity; these I will now give, together with a rough estimate of the consumption in the United States. The most extensive use of the ore is in the making of bleaching powders (chiefly chloride of lime). According to the report previously quoted, the amount of manganese imported into the Tyne district alone for this purpose was then (1863) given as 11,400 tons per annum, at 41. stg. per ton. Although this district is a very considerable seat of chemical manufactures, there are other parts of the kingdom where very large quantities of manganese are required, among which, the most important are Liverpool, the seat of Messrs. Muspratt's, and Glasgow, of Messrs. Tennant's works. Accordingly, we find in the "Statistics of the Alkali Trade of the United Kingdom for 1862," that the annual consumption of manganese was then 33,000 tons for the manufactures depending on the products of the alkali trade-viz., soap, glass, paper, cotton, woollen, linen, colour making, and all chemical manufactures of any magnitude. This estimate, however, takes no account of the ore used in making iron, and the demand for bleaching powder has been increasing of late years, partly owing to the use of grass, and perhaps of other materials, in the making of paper. The quantity of manganese ores used in the United States was a year ago estimated by a gentleman dealing in them in Boston, at about 500 tons per annum, by another gentleman this year at 1000 tons.

With regard to the quality of the ore required in certain cases, it is found that in making bleaching powder, the ordinary ores, containing from 65 to 75 per cent. binoxide along with water, oxide of iron, car

bonate of lime, barytes, etc., answer so good a purpose, that the rich pure ores, such as that from Teny Cape, are not bought for this use, unless at a price far below that given by those who require only such ores. One of the firm of Tennant and Co. (makers of bleaching powder), said, for example, that he could not afford to use Teny Cape ofe, meaning, I suppose, at the high price it would fetch from glass makers, for, as J. Outram, Esq., jun., informed me, the Spanish ore of from 70 to 75 per cent. binoxide, sells for 55s. to 60s, sterling per ton, and therefore the bleaching powder makers will give only about 57. 10s. for Teny Cape ore, containing upwards of 90 per cent., while, as we have seen, this actually brought as much as 97. and even 10l. stg. per ton. This high price was given by glass and pottery makers who require an ore as free as possible of iron; this, at any rate, is the case with the former, who employ it to remove the stain of iron from the finest kinds of glass. Mr. Outram said that he thought even 2 or 3 per cent. of iron would interfere with the sale of ore at 93 per cent. binoxide for this purpose, and it was because the Teny Cape ore gave less than per cent. of iron, with 915 per cent. binoxide of manganese, that it brought the high prices obtained. The demand for these pure rich ores is comparatively limited, perhaps a few hundred tons a year are fully as much as would find sale at the highest prices named. That there is always a steady demand for ore useful for making bleaching powder, is shown by the efforts made to restore to its original state the oxide employed; patents have been taken out for this purpose, and one is recommended by its owner as restoring the material to 52 per cent., and as being capable of bringing it up to 70 per cent. binoxide, which, as we have seen, is a very moderate percentage in the ores.

With regard to the other applications of manganese, the making of iron and steel is the most important. Manganese renders iron tough, and steel better and more durable; in the latter case it acts by removing sulphur and silicon. Although the quantity of manganese actually imparted to the iron and steel is very small, in a manufacture of such enormous proportions the consumption must be large if continued. The making of manganates and permanganates, which are used as oxidising agents and in disinfecting, must also be extensive, a prize medal having been given to Mr. Condy in 1862 for the manufacture of such salts on the large scale. As an illustration of the way in which the ores are sometimes treated in practice, I may mention the mode adopted by Mr. Hobbs, of Boston, who has had a great deal to do with the Upham and Shepody ores of New Brunswick. The ore is washed clean at the mines, boxed up, and sent to Boston, when it is selected into three good qualities and refuse; the three good sorts are ground in three mills till fine as flour, put up in barrels papered inside, and the contents of each barrel are assayed and sold according to assay.

The first quality free (?) of iron and containing about 98 per cent. of peroxide of manganese, is used for making the finest (flint) glass. The second quality (also no doubt pretty free of iron) containing from 75 to 80 per cent. peroxide, is used for making white phials. The third, containing about 70 per cent. peroxide, is employed for making common glass bottles; while the refuse, containing perhaps 25 or 30 per cent. iron, is used either in making clear amber-coloured bottles for brandy, &c., or for carboys.

In conclusion I state together the quantities of binoxide of manganese contained in some of the Nova

The alum is made direct from the shale found underlying the seams of coal in South Lancashire. The shale is black from the organic matter contained in it, which amounts to about 5 or 10 per cent. It is piled in heaps about twenty feet long, four to five feet high, and two to three broad. There is a brick drain along each to supply air. The heaps are ignited by a small quantity of burning coal, and the combustion goes on by itself. It is thus slowly calcined at a heat approaching to redness, the object being to render the alumina of the shale soluble in sulphuric acid. If the temperature be too high the clay vitrifies, and the alumina is then insoluble in sulphuric acid. The calcination lasts ten days; when finished the shale is of a pale red colour. It is then put into long tank-like vessels, about forty feet long, ten feet wide, and about three deep; they are technically called pans; they are made of sheets of cast-iron screwed together. These pans are lined with lead. When they are ready to be charged with shale the bottom of each pan is covered with tiles about nine inches square—this | is to prevent the shale coming in contact with the lead, because the heat would dry the shale and burn the lead. The charge for one pan is about twenty tons. It is digested with about ten tons of sulphuric acid of sp. gr. 125. For about four or five days the liquid is kept up to a temperature of about 220° Fahr., partly by fire underneath the pans, and by the introduction of ammonia from gas liquor, which is boiled down in boilers; steam is also driven in, which raises the temperature considerably. From time to time the liquor is tested to see if it be of the proper strength. A small quantity is put into a square shallow leaden dish, and according to the time it takes to crystallise it is known whether the liquor is ready to be drawn off into the coolers. The cooler is a large rectangular leaden vessel about twenty-nine feet long, seventeen feet wide, and one foot nine inches deep. When the liquor is in the cooler it is constantly agitated with a long wooden arm (worked by a steam-engine) to prevent the formation of large crystals. On an average the liquor is left in the

cooler for about fourteen hours; at the end of that time there is a bed of small crystals deposited several inches in depth. The deposit has a greenish colour, due to sulphate of iron. These crystals are then thrown into a large square box lined with lead. They are then washed by means of the mother liquor, and the crystals allowed to drain. This operation takes about two hours. When they are thoroughly washed, the crystals are thrown upon an iron grating, the bars being about half an inch apart from each other. This is done to break the lumps and wash out the mother liquor. Now the alum is ready to be re-dissolved by steam. For this purpose a strong cylindrical vessel is used, from two to three feet high and about two feet in diameter. It has two divisions; one part of the cylinder is open to allow the crystals to be thrown in, the other part has a division and is closed. This division is to prevent large crystals passing without being dissolved. At the bottom of the open part of the cylinder is a coil of lead pipe containing small holes, through which a current of steam, about twenty pounds pressure, is driven through these holes, which, passing through the alum, dissolves it as fast as one man can throw it in. At the top of the cylinder is a pipe, which communicates with a wooden tank lined with lead, and which is called the dissolving box; it is three feet deep, fourteen long, and eight broad; this is to receive the solution of alum before it is drawn off into the tubs or roaching pans; the solution remains in this tank for about three hours; it is covered over with boards, and the joints closely packed with cotton waste. When this tank is nearly full, and while the steam is still on, about four quarts of size are poured in by means of a pipe; this is to cause the floating impurities to settle. When the solution is ready to be tapped off into the crystallising vessels, the tubs which are at the other end of the shed (say sixty feet from the tank) are filled a few minutes before those that are closer; the solution is hotter and the stream swifter, because the appearance of the alum after crystallisation depends upon the temperature at which the boxes have been filled. When it is too hot it forms large crystals outside, and when the temperature is right the outside of the block of alum is like a loaf of sugar; the crystallising tubs are built in pieces. At the bottom is a large round flagstone, and the pieces (each of which is lined with lead) are built round it, and kept in their places by strong iron hoops screwed together. The diameter of the tubs is wider at the bottom than the top, and they are about six feet high. When the hot solution is drawn off into these tubs, they are covered with a wooden cover. In about four days the sides of the tube can be taken down, as there will then be a sufficient thickness of alum to hold the mother liquor; it now stands in this condition for about fourteen days longer. A hole is then made in the lower part of the block for the liquor to run out, which is collected in a tank. The block is then broken up, and the inside is studded with beautiful crystals, which have a slight violet colour, due most likely to some of the aniline colours. The alum is now ready for the market. One of these blocks weigh about four tons; the bottom part, which is not so white and clean as the other, is returned to the dissolving box; the alum crystallises in truncated octahedrons.

The present employment of alum in the arts is very extensive; it is largely used by the calico printers, from which they prepare the acetate of alumina, as this is used for a mordant in dyeing and calico-printing, and is generally prepared by precipitating alum with acetate of lead. Acetic acid retains the alumina with less

NEWS

energy than the other acids, for which reason this salt is now generally substituted for alum, because the acetic acid gives up the alumina with such readiness that mere elevation of temperature is sufficient to effect the separation of these two substances. Alum is largely used in the manufacture of paper, for the size it contains is to prevent decomposition, and also in bookbinders' paste, which is made of flour and one-sixth of alum. In the preparation of leather baths of alum are used; such as in preparing the white sheep leather twelve, fourteen, and sometimes eighteen pounds of alum are used for the bath containing 100 skins, with the addition of common salt, and in the case of calf and lamb skins with their hair and wool on, the bath is stronger. One pound of alum and one pound of salt are required for a single calf skin, and the leather of Hungary is made by impregnating strong hides with alum, common salt, and suet, and in the colouring of morocco leather the puce colour is communicated by logwood with a little alum. When alum is added to tallow, it makes the tallow harder. Printers' cushions and the blocks used in the calico manufactory are rubbed with burnt alum to remove any greasiness which might prevent the ink or colour from sticking. Alum is used in medicine, and also for domestic purposes, for water can be purified by means of it; the mud that water holds in suspension collects on the addition of ooo1 parts of alum (this is equal to seven grains per gallon) in long thick streaks, coagulates as it were, and is immediately precipitated. This process, the principle of which is inexplicable, was first introduced by the Chinese, and has been imitated in various parts of the world. The operation was well known from a very early period in the Highlands of Scotland, according to Dr. Clark, where it is practised with reference to peat water. The Parisian laundresses use it, but it has not been introduced into any of the establishments for the purification of drinking water, partly because alum is a substance never naturally combined in water, and may be received as a real impurity, and partly on account of public prejudice-(Richardson). In bottling fruits for preservation alum water is used. A novel application of the use of alum is seen in the lining of Milner's iron safes; he uses a mixture of alum and sulphate of lime; this makes a capital mixture for such a purpose, as the alum contains twenty-four equivalents of water; when the safe is heated, it keeps the sides cool from the evaporation of the water, thus the contents of the safe remain uninjured. There is no doubt but that alum is largely used in the process of adulteration, every one knows that it is used in the manufacture of bread; it causes the bread to be whiter than it otherwise would be. According to Liebig it is very injurious, as he supposes the soluble phosphate to combine with the alumina, forming insoluble salts, and the beneficial action is lost to the system. Some have defended the use of alum in bread, because the water was alkaline; but when we have such high authority that it is hurtful to the body, all who have the power should try to prevent its being used for such a purpose. The use of it in bread is prohibited by law under certain penalties, but the law is rarely enforced. In the manufacture of lard alum is used as an adulterant. Dr. Hassall says that alum is generally put into the vat in breweries, as it gives the beer a smack of age; it also gives a heading to the porter which landlords are so anxious to raise to gratify their customers; also in the adulteration of gin alum dissolved in water is used, and in the case of artificial port wine, alum is added to increase the brilliancy of its colour.

From the foregoing we see that there is a pretty brisk demand for this important salt. Mr. Spence has now become the largest manufacturer in the world, for he makes nearly 7000 tons a year. A few years back the quantity he turned out was a little over 1000 tons, but owing chiefly to the large amount of mechanical skill and chemical science he possessed, he was enabled to raise seven times the quantity he did before. Not only in alum has he made such improvements, but in many other things, for he has now solved the longvexed question of the abatement of the copper smoke of Swansea.

PROCEEDINGS OF SOCIETIES.

SOCIETY OF ARTS.

CANTOR LECTURES.

"On some of the most important Chemical Discoveries made within the last Two Years."

By Dr. F. CRACE CALVERT, F.R.S., F.C.S.

LECTURE I,

Tuesday, April 4, 1865.

(Concluded from page 212)

Now, let us return to the subject under consideration. viz., that a spectrum is produced by the decomposition of light when it is refracted at an angle of 60°; and that the result of that decomposition is the production of three primary and four binary or complementary colours. Further, that the red portion of the spectrum represents calorific rays of light; that the green and yellow represent light-giving rays, and violet and the rays beyond it the chemical or actinic rays of the same. Philosophers have for a long period been able to measure accurately the meter or the thermo-electric pile; and though we had a intensity of the heat-giving rays, by means of a thermogeneral knowledge of the intensity of the chemical rays of light, still we had no method of accurately measuring its real intensity, and conveying our results and observations to others, till Profs. Bunsen and Roscoe filled up this important gap. These gentlemen's researches will be of great service to science and to society, as they will throw much light on many meteorological data, and enable a chemist to study with more precision than has been previously done the chemical phenomena of vegetation and other phenomena connected with the chemistry of agriculture. For, example, the thermometric observations giving the mean monthly or yearly temperature of a country, by no means yield all the data required for the estimation of the true climatology of the place, or of its plant or animal producing capathe amount of solar heat directly or indirectly reaching bilities. For these purposes we require to have not only the spot, but likewise the amount of chemical active solar light which may be present there. This is strikingly exemplified by the following example given by Dr. Roscoe on a comparison of the mean annual temperature between Thorshawn, north latitude, 62°2′; west longitude, 6°46; temperature, 45°6′; and Carlisle, north latitude, 54° 55'; west longitude, 2° 58"; temperature, 46'9°; difference, 13. From these figures it will be seen that the mean annual temperature is nearly equal, but the quantity of sunlight falling upon those two places differs most widely, and we have a corresponding difference in true climatological results. Thus the flora of the Faroe Islands and the Shetland Islands is of a most limited description. Only hardy varieties of shrubs, and no trees or flowers, exist there, while at Carlisle we have a luxuriant vegetation accompanying a most sunny sky. How essential, then, are the rays of light to vegetation. These gentlemen have also ascertained that those rays are in

ratio with the intensity of that light; and still further they are also in ratio with the chemical or actinic rays of the sun; and thus the researches of these savants will enable them to measure with accuracy those chemical actions. It is impossible, in a lecture like this, to render justice to their researches, therefore I must refer those who wish to consult them to the Philosophical Transactions of the Royal Society. Still I may state that these gentlemen's photochemical instruments are based on the following data, namely, that equal intensity of light produces in the same given space of time equal shades of tint on surfaces prepared with chloride of silver of uniform sensitiveness. Thus it is shown by experiments that a tint attained by paper so prepared is constant when the quantity of light falling upon it also remains constant. Light of an intensity of 50° falling upon a paper for the time of one minute produces the same blackening effect as light of the intensity of one falling upon it for the time of fifty minutes. Knowing these laws which regulate the degree of shade of the paper, and having a surface of a perfectly constant degree of sensitiveness, it is easy to obtain the absolute measurement of the chemical action of light.

The next discovery to which I desire to draw your attention is still in its infancy; but I am induced to refer to it from two considerations. The first, that it may render great service to society by enabling us to preserve the lives of many thousands of our fellow-creatures in our coal-mines and other underground works, and also because it is a beautiful illustration of the amount of knowledge that a man requires at the present day either to understand or appreciate fully the discoveries of others, or to enable him to attempt any original invention of his own. Unless a person possesses the rudiments of the leading sciences of the day he will never be anything but an imitator, and will never succeed in improving the inventions already made. It is certainly most interesting to witness how the most abstruse branches of science are brought to bear on arts and manufactures, and no better example can be given than the application of electricity under various forms to what is commonly called the telegraph. The invention which I am now about to bring to your notice is due to M. Dumas, a young French engineer, and to M. Brequet, of Paris, who is also practically connected with telegraphy. To enable these gentlemen to carry out their discovery, they have had to study, and be perfectly acquainted with, the researches of many of the most eminent men that science has produced during the last half century. Thus they only employ the galvanic battery which was discovered by Galvani, and perfected by many philosophers, until brought at last to its present perfection. They use a mixture of bichromate of potash and sulphuric acid in a Bunsen battery. They have also had recourse to magneto-electricity, first discovered by Faraday, and brought to its present perfection by the researches of MM. Nobili, Mason, Becquerel, Joule, and others; and to enable them to construct their apparatus they have applied, with great ingenuity, the induction coil, the result of many successive discoveries, and brought to great perfection by Ruhmkorff, the vibrating interrupter of Dancer, and also the condenser of Fiquier. Further, they must have had the knowledge of the stratified light and the application of it by Gassiot: the fluorescence of light by Stokes and Becquerel, and their applications to glass by Geissler. All these facts prove the correctness of my statement, how vast is the amount of knowledge required to make a little discovery. The apparatus invented by these gentlemen is portable, for a miner carries on his back the above-mentioned galvanic battery, and this generates the force required, which is multiplied, increased, and brought to light by the Ruhmkorff coil, which is also confined in the same leather case, occupying only six inches; the magneto-electricity passes through wires covered by vulcanised india-rubber, and these are

in connection with a thick glass tube, in which a vacuum has been made, and this contains a fluorescent tube of Geissler, which becomes luminous or fluorescent by the passage of the electricity through it, generated by the coil and the battery.

Although both light and electricity are most interesting subjects, and could well be made the subject of many lectures, still I am bound to leave them on one side, and draw your attention to other facts deserving of notice. It is well known to all chemists and philosophers that matter has a great tendency to assume a geometrical or crystalline form, and that whenever the atoms of matter are sufficiently free for molecular attraction to have its full influences attraction between the atoms takes place, and gives birth to well-defined crystals. The following examples can be cited:-The slow condensation of the vapour of iodine, which gives rise to well-defined crystals as well as those of camphor and other volatile bodies. When sulphur, bismuth, and other substances are melted, and allowed to cool slowly, and the excess of the fluid remaining among the crystals is poured off, well-defined crystals are found to exist in the mass, which apparently would have disappeared had not the excess of fluids been poured off, for in this case the molecules of the remaining fluid mass would have solidified among the crystals, and would have prevented the observer from seeing that the molecules when freed in the fused mass had assumed a crystalline form. The tendency of molecules to assume a geometrical form presents in many instances curious phenomena. Thus, for example, a vessel may contain acetic and carbolic acids; and if, say at a temperature of 40° or 50°, a crystal of either of those substances is placed in contact with its own fluid, the entire bulk of fluid passes in a few seconds into a solid crystalline mass. The manifestation of that force is also beautifully illustrated in the following instance :-If a tin plate be heated to a moderate temperature, and a drop of water be allowed to fall on its surface, and the plate be dipped for a few minutes into weak muriatic acid, it will be observed that the whole surface of the plate is affected, and that where the water fell it has assumed a most beautifully waved and iridescent surface. If this surface be examined under the microscope, it will be found that under the influence of the vibrations generated by the cold fluid falling upon the heated plate the mass of molecules have passed from their amorphous condition to that of a crystallised one. We all know this alteration in the tin-plate surface was particularly applied many years ago to produce variegated surfaces on our tea-trays and other similar domestic vessels. It should also be stated that this effect was greatly enhanced by the skilful application of coloured varnishes, which increased the value of the mercantile article. This discovery, which is due to an eminent chemist of the name of Prout, clearly proves, as those before cited, the power which matter has to assume a crystalline form. I cannot, however, refrain from adding the following instances, in which the mere vibration of particles of matter is sufficient to change amorphous bodies into crystalline ones. The first is that which often takes place in the iron used on railways. The most striking example is that of the iron links used to unite waggons, where it is found that the fibrous, tenacious link made of malleable iron is transformed into a crystallised, brittle link by the constant vibration it is subjected to by railway traffic. Another example is that shown by the peculiar action exercised by intense cold on the molecular state of iron, as shown by the brittleness of the metal in Russia and other cold climates; this was the case in December, 1859, in England, when, as will be remembered with regret, many railway accidents occurred, owing to the rails becoming crystallised and brittle.

The power which molecules have to assume a crystalline form has recently been the study of Mr. F. Kulhmann, an eminent chemist, of Lille, and he has given to that force