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being transformed into an amber-yellow viscid mass, | quartary iodides; but, together with these compounds, exhibiting no longer a trace of crystalline structure. If there is formed a tertiary iodhydrate, the base of which the temperature be then raised to the melting-point of is readily separated by distillation of the product with an lead (335) a further change is manifested by the amor- alkali. The base thus liberated has the V.W. 09293, and phous resinous substances having solidified again to a boils at 196°. Analyses of the platinum-salt proved it to hard mass of large radiated, generally rather coloured be dimethylated xylidine, crystals. On opening the digestion-tubes, appreciable quantities of uninflammable gas are evolved.

The products formed at moderate and extreme temperatures essentially differ from one another. This is seen at once when the iodhydrates produced in both cases are decomposed by alkali, and the bases thus liberated are submitted to distillation in a current of steam. The

volatility of these bases shows the absence of quartary compounds; but whilst the monamines formed at moderate temperatures unite with acids to an extremely soluble salt, which are scarcely to be crystallised, those which are produced at high temperatures are found to solidify to rather difficultly soluble (readily crystallisable) salts with acids. The former bases exhibit the characters of tertiary and secondary, the latter ones those of primary monamines. Under these circumstances, it appeared desirable separately to examine the products formed in different conditions of temperature.

On submitting the iodhydrates formed at 220°-230° to distillation with alkali, a basic oil is obtained, which, when rectified after drying over hydrate of potassium, boils between 200° and 280°. By repeated distillation, the boiling-point is considerably lowered, small quantities of substances boiling beyond the range of the thermometer being separated. Finally, by far the greater portion of the bases is found to pass between 186° and 220°. This liquid consists of two varieties of dimethyltoluidine, of methylxylidine, and small quantities of dimethylxylidine. Of the two dimethyltoluidines, the one has the V.W. 09324, and boils constantly at 186°: the other has the V.W. o'9368, and boils at 205°, i.e. 19° higher than the former one. The nature of these two bases was fixed by the analysis of their platinum-salts,

2[C6H4.CH3) (CH3)2N.HCI].PtC14,

and also of the quartary iodide, (C6H4.CH3) (CH3)3NI, into which they were converted by the action of methyl iodides, and the platinum-salts corresponding to these iodide, 2[(C6H4.CH3)(CH3)3NCI].PtC14 The two dimethylated toluidines here described obviously correspond to two of the three modifications of toluidine, and very probably to the two liquid modifications. Dimethyltoluidine, obtained by converting solid toluidine into the trimethylated toluyl ammonium iodide, and then submitting the corresponding hydrate to distillation, has a V.W. o 988, and boils at 210°. The substance thus obtained, the composition of which was also established by analyses of the platinum-salt, essentially differs from the isomeric base boiling at 186°; it is less easily distinguished from the base boiling at 205°, with which more particularly it much agrees in odour; in fact these two compounds exhibit only the slight difference of 5o in their boiling-point. Still I believe them to be isomeric, not identical.

The presence of methylxylidine being only indirectly desirable to establish the nature of the latter by addiproved by analysis of the dimethylated base, it appeared tional experiments. For this purpose the tertiary monamine was converted, by means of methyl iodide, into the quartary compound, the characters of which could not be mistaken, its composition being, moreover, established by analysis of the beautiful platinum-salts.

2 [C6H3(CH3)2)] (CH3)3NCI].PtC14

In performing these experiments I was astonished to observe how difficultly dimethylxylidine combined with methyl iodide. Digestion at 100° produced no effect, and only heating the mixture for many hours to a temperaExamination of the Monamines formed at moderately ture of 150° combination took place, but even then only High Temperatures. to a very small extent.

It was this indifference of dimethylxylidine towards methyl iodide which enabled me to discover that small quantities of this compound are always formed, together with the monomethylated xylidine, when trimethylated phenylammoninm iodide is submitted to the action of heat. On treating the liquid, chiefly consisting of the two dimethylated toluidines and of monomethylated xylidine, with methyl iodide, these bases, as I have pointed out, are converted into iodine compounds; the small quantity of dimethylxylidine, which as such exists in the liquid, remains behind with the excess of methylic iodide, from which it may easily be separated by means of hydrochloric acid.

It deserves to be noticed that while the boiling-point of solid toluidine (202°), by the introduction of two methyl groups, is raised by 8°, the boiling temperature of one of the liquid modifications (1989) is lowered by not less than 12°. Phenomena of this kind have been observed repeatedly in the course of this inquiry.

It was mentioned already that, in addition to the two dimethylated toluidines, the products of the action of heat on trimethylated phenylammonium iodide contains methylxylidine. I have not been able to isolate this compound; but it was not difficult to prove its presence by the action of methyl iodide on the mixed bases. The two dimethylated toluidines are thus converted into

C10H15N [C6H3(CH3)2] (CH3)2N, which previous to methylation must have obviously existed in the form of monomethylated xylidine, C9H13N. [C6H3(CH3)2] CH3.HN.


The formation of dimethylated toluidines and of monomethylated xylidine, requires no special explanation; it is due to intramolecular atomic interchange.

C6H5(CH3)3NI=(C6H4. CH3) (CH3)2 N.HI. = [C6H4 ⋅ (CH3)2] CH3HN.HI. For the generation of dimethylxylidine it is necessary to supply a methyl group from without. I have, however, already pointed out that, along with the principal transformation, several secondary reactions are taking place; those I hope to examine more minutely by-and-bye. Dimethylxylidine, which occurs in comparatively small quantity, obviously belongs to such a secondary change. The complementary product is probably monomethyltoluidine,"

[C6H5(CH3)3NI] = (C6H4.CH3)CH3HN.HI, +[C6H4-(CH3)2] (CH3)2N.HI, which I have not, however, as yet been able to trace,

Whilst engaged with these experiments, I have, for the sake of comparison, converted a specimen of xylidine obtained from aniline-oil of high boiling-point into dimethylxylidine. The xylidine employed had constant boiling at 216°. The tertiary base procured from it was observed to boil at 203°, i.e., 7° higher than the compound derived from trimethylated phenylammonium iodide; from this last derivative it differed, moreover, by combining much more readily with methyl iodide. The quartary compound thus formed often remains liquid for days, and then suddenly solidifies into a beautiful mass of crystals.

Examination of the Monamines formed at High

It has been already stated that the bases into which trimethylated phenylammonium iodide is converted at


New Method for Producing Amides and Nitriles.

very high temperatures (melting-point of lead), unmistakably exhibit the character of primary monamines. The only primary base which can arise from trimethylated phenylammonium iodide by intramolecular atomic interchange is a trimethylophenylated monamine, i.e., a cumidine, C6H5(CH3)3NI = [C6H2(CH3)3] H2N.HI. This, I may at once observe, is indeed the principal product of the reaction. It cannot, however, be wondered at that, under the influence of such extreme temperatures, many collateral changes must take place. The presence of dye-products is at once perceived, when the crystalline contents of the digestion tubes are submitted to distillation in a current of steam. Together with the vapour of water, a colourless oil is volatilised, consisting of hydrocarbons partly solid, partly liquid, the examination of which will form the subject of a future communication. Addition of an alkali to the liquid in the retort liberates considerable quantities of monamines, which, when dried over iodiamhydrate, are observed to boil between 225° and 260°. By repeated distillation this range of boiling is still considerably expanded; at the same time, by far the largest portion of the liquid is found to pass between 217 and 230°. The primary nature of this main fraction not only, but also of the bases, having both a lower and higher boiling-point, is at once manifested by the crystallising power and insolubility of the salts which they produce. At whatever stage of the distillation a drop of the liquid passing be mixed with dilute hydrochloric or nitric acid (invariably splendid), needles of chorhydrate or nitrates are formed, the solutions of which, even when considerably diluted, solidify with platinum perchloride double salts generally well crystallised. Another experiment rapidly indicating the primary character of these monamines may here be mentioned. On adding benzoyl chloride to the several basic fractions, much heat is evolved, and after cooling crystalline masses are produced, which are separated by water into soluble chlorhydrates and insoluble benzol compounds remaining behind, which may be crystallised from alcohol. None of the many secondary and tertiary monamines which have passed through my hands in the course of this inquiry exhibit this deportment, and accordingly benzoyl chloride may be recommended as a valuable reagent, readily applicable for primary bases. The method of recognising primary monamines which I have pointed out some time ago, and which consists in converting them, by means of alcoholic potash and chloroform, into the powerfully smelling isonitrites, may also with advantage be resorted to.

The liquid boiling between 217° and 230° was separated by distillation into four fractions, each of which was then converted into a magnificently crystalline chlorhydrate. These several salts, after re-crystallisation, were all found to contain [C6H2(CH3)3]H2N.HCl, and to yield platinum-salt of the composition

2 [[C6H2(CH3)3] H2.N.HC1] .PtC14.

I was thus led to believe that the fraction boiling between 217° and 230° consisted of several isomeric cumidines; but on separating the bases from the several chlorhydrates, it was found that they all contributed very nearly the same boiling-points. The liquid thus obtained boiled between 225° and 227°, and had the V.W. 09633; it did not solidify when exposed to a temperature of -10°. I am therefore inclined to assume that only one cumidine is formed by the action of heat on trimethylated phenylammonium iodide, and that the irregularities in the boiling point of the original fraction must be due to the presence of small quantities of impurities.

It deserves to be noticed that cumidine obtained from aniline, when heated with corrosive sublimate, no

trace of red colouring-matter, whilst a splendid crimson is at once produced if a mixture of this base with pure

aniline be treated. I reserve for a future communication the study of the colouring-matter thus obtained.

* Hofmann, D. Chem. Berichte, 1870, p. 767.


Taking into consideration the general observations recorded in the preceding paragraphs, the compound here designated as cumidine was naturally assumed to be a primary monamine. Little doubt as this conception appeared to present, it had nevertheless to be proved by experiment; for this purpose the base was submitted to methylation. Cumidine is readily acted upon by methylic iodide at the common temperature. Since it was only necessary to establish the degree of substitution the first product of methylation was at once submitted to a second treatment; this second methylation likewise commenced at the common temperature, but had to be finished in the water-bath. The dimethylated base thus obtained has the V.W. 09076; it boiled between 213° and 214°; hence, in this case also, the insertion of two methyl groups had lowered the boiling-point. Dimethyl cumidine may be cooled to -10° without solidifying; like all tertiary monamines, it forms very soluble salts, but gives a very beautiful platinum salt, containing

2 [[C6H2(CH3)3] (CH3)2N.HC1] .PtCl. Remarkably enough, dimethylated cumidine exhibits the same reluctance to form a quartary compound with methyliodide that has already been pointed out as a peculiarity of the tertiary xylidine. But whilst in the case of dimethylxylidine, though difficultly and sparingly, combination after all took place, all attempts with dimethylated cumidine have hitherto failed. The base was heated with methylic iodide for days in the water-bath, and ultimately even to 150° without any result. This inability of forming quartary compounds must in one way or another depend upon the arrangements of the material within the molecule. At all events, it deserves to be noticed that there are dimethylated xylidines and cumidines which readily combine with methyl iodide. The dimethylated bases existing in the less volatile fractions of commercial dimethylaniline, all form quartary compounds without difficulty, and must therefore correspond to xylidines and cumidines, which differ from those derived from trimethylated phenylammonium iodide.

In what relation stands the cumidine above described Of the several purely to the cumidines already known? methylic cumidines which are possible, two only are somewhat accurately known; these are the two bases, which are derived, the one from so-called pseudocumol (obtained by treating xylilic bromide and methylic iodide The former with sodium), the other from mesitilol. cumidine is a solid, fusing at 62°, and need not therefore be further considered here. Most probably the cumidine above described will prove identical with the primary Unfortunately, monamine corresponding to mesitilol. mesitylamine has been hitherto so little studied, that even its boiling-point is not known. I hope next winter to examine more minutely this group of compounds.

In conclusion, I have great pleasure in expressing my best thanks to Mr. E. Mylius, assistant in the Berlin Laboratory, for the zeal and care with which he has furthered the progress of these researches.


By E. A. LETTS, Berlin University Laboratory.

SOME time since Professor Hofmannt has shown that phenyl mustard-oil, when acted on with acetic acid under pressure, is converted into phenyl-diacetamide, carbonic anhydride and sulphuretted hydrogen being separatedCS C6H5

CH, N+ 2(C2H3O-OH) = (CHO), N+ CO2 + H2S. Bearing this reaction in mind, the question arose as to


* A Paper read before the Royal Society.

+ Hofmann, Beriche. d. Deutch. Chem. Gessell., 1870.

how the metallic sulphocyanates would behave under similar circumstances; at Professor Hofmann's suggestion I have submitted this question to an experimental investigation.

Action of Acetic Acid on Potassium Sulphocyanate.

Supposing the potassium salt of sulphocyanic acid to undergo a change analogous to that observed with the phenyl mustard-oil, it was to be expected that I molecule of this body would react with 3 molecules of acetic acid to produce i molecule of potassium acetate and I molecule of diacetamide, carbonic anhydride and sulphuretted hydrogen being evolved

KCNS+3(C2H3O-OH) = =C2H3O-OK7(C2H3O)2HN + CO2 + H2S.

The reaction, however, takes a different course. In my first experiments the acetic acid was allowed to react on the sulphocyanate under pressure; but it soon became evident that this was unnecessary, simple digestion of the two bodies in a flask provided with an upright condenser being amply sufficient.

The powdered salt dissolves readily in the boiling acid, and an immediate and copious disengagement of gases ensues, in which carbonic anhydride and sulphuretted hydrogen may be readily recognised. Considerable time, however, elapses before the sulphocyanide is completely decomposed, some three or four days being required for a mixture of 100 grms. potassium sulphocyanate and 180 grms. acetic acid. At the end of this time the products of the reaction were submitted to distillation and commenced boiling at 170°-180°; the thermometer, however, rose rapidly to 216°; and between this temperature and 220° the distillate solidified in the receiver to a radiating crystalline mass, which analysis showed to be pure acetamide. Above 220° nothing further distilled, the residue in the retort consisting wholly of potassium acetamate. In what manner had acetamide been formed, instead of diacetamide expected in the reaction? It appeared not unlikely that the acetic acid employed contained some water, and that the diacetamide produced in the first instance was thus converted into the mono-compound



To remove any water which might possibly have been present, the acetic acid was treated with phosphoric anhydride, and the experiment with the sulphocyanate repeated; but even now acetamide was exclusively obtained.

On submitting, however, the gases evolved during the reaction to a closer examination, the formation of acetamide became at once intelligible. It was found that a large proportion of these gases consisted of carbonic oxysulphide (COS). To prove the presence of this compound, it was only necessary to pass the evolved gases through a bottle containing a slightly acid solution of lead, by which the sulphuretted hydrogen was retained: thus purified, they produced no further precipitate when passed through a second bottle containing the same solution; but precipitation at once took place if this solution were rendered alkaline by soda or ammonia. This is the characteristic behaviour of carbon oxysulphide, which was further identified by its odour, great density, and inflammability.

The principal reaction that takes place when acetic acid is treated with potassium sulphocyanate is accordingly as follows:


The liquid products passing over before 216° yield considerable quantities of the amide on fractionation; this remark applies to the other experiments with the fatty acids to be presently described.

The sulphuretted hydrogen and carbonic anhydride, produced simultaneously with the carbonic oxysulphide, are the complements of a second reaction; the principal product of which I have not the least doubt is acetonitrile.


C2H3O-N-H2+COS=C2H3 N+H2S+CO2.

I must remark, however, that I have not actually proved the formation of this body by experiment. My investigations in the acetic series were completed before this phase of the reaction was thoroughly understood, and thus, probably owing to its low boiling-point (77°), the acetontrile had been carried off with the stream of disengaged gases, and had escaped detection. I have not repeated the experiment, because in other series it has been easy to demonstrate the formation of the nitrile.

Action of Isobutyric Acid on Potassium Sulphocyanate.

If potassium sulphocyanate be heated with isobutyric acid (which may now be readily obtained in a state of purity by oxidation of the isobutyric alcohol separated from fusel oil), the salt melts under the acid to an oily layer, from the surface of which bubbles of gas are plentifully disengaged, consisting, as in the preceding case, of carbonic oxysulphide, carbonic anhydride, and sulphuretted hydrogen. In consequence of higher boilingpoint of isobutyric acid (154°), the reaction proceeds more rapidly than with acetic acid. If the mixture be submitted to distillation when all disengagement of gas has ceased, it begins boiling a few degrees above 100°, the thermometer rapidly rising to 216°; during this time an aromatic liquid passes over, possessing the odour of butyric acid.

Between 216° and 220° the thermometer remains tolerably constant, the distillate solidifying in the receiver to a white crystalline mass. On fractionating the liquid portion passing over before 200°, no product can be obtained showing a constant boiling-point; but on treating it with a solution of caustic soda, an oily aromatic liquid of characteristic odour floats on the surface, which, separated by a large funnel and dried over calcium chloride, boils constantly between 107° and 108°. Its composition and reactions characterise this substance as isobutyronitrile. H-C-(CH3)2 CN Theory.

C4. H7 N..


[blocks in formation]

Experiment. 68.93




Boiled for some time with an alkali, this nitrile is converted into isobutyric acid and ammonia. The complementary products attending the production of this body are carbonic anhydride and sulphuretted hydrogen, whose copious evolution have already been mentioned.


Isobutyronitrile has been prepared by Merkownikoff.* potassium, but probably not in a state of purity, as he He obtains it by treating isopropyl iodide with cyanide of gives 80° as its boiling point; whereas 107° to 108°, the number obtained by myself, approaches more closely that observed for the normal butyronitrile (114). The crystalline substance before described as passing over between 216° and 220° is the amide of isobutyric acid


H-C= (CH3)2

*Merkownikoff, Jahresb., xviii., 318.

[blocks in formation]





[blocks in formation]

Action of Valeric Acid on Potassium Sulphocyanate. In this instance, too, the reaction proceeds according to the two equations




The separation and purification of the valeronitrile and valeramide is similar in all respects to that employed for the corresponding compounds in the butyric series. Valeronitrile, already investigated by other chemists, boils between 125° and 128°. By treatment with fumic nitric acid, it is converted into a crystalline substance (perhaps CsH8(NO2)N), which I have not as yet been able to examine further.

Valeramide closely resembles the isobutyramide. It is a white crystalline body of pleasant aromatic odour, recalling that of the valerian root: it is soluble in water, alcohol, and ether; in the last-mentioned liquid much more so than the isobutyramide. From hot water it crystallises in large right-angled but very thin plates. Valeramide fuses between 125° and 128°, and sublimes in the same manner as isobutyramide below its boiling-point, which lies between 230° and 232°. It distils without decomposition.

Action of Benzoic Acid on Potassium Sulphocyanate. The aromatic acids, Cn H(2n-8)O, series react in an analogous manner with potassium sulphocyanate, with the difference, however, that here nearly exclusively the nitrile is formed. The production of amide is so insignificant as to be scarcely recognisable. The reaction with benzoic acid takes place with particular facility according to the equation


2 mols. benzoic acid and I mol. potassium sulphocyanate (both in a perfectly dry condition) are placed in a retort, to the mouth of which a long wide tube is attached to

It is remarkable that acetamide, butyramide, and isobutyramide all have the same boiling-point, namely, 216° to 220°.


serve as condenser. The apparatus thus arranged is placed vertically, and heated either in a paraffin-bath or over the naked flame. Both bodies melt, forming two layers, of which the benzoic acid is the lower. At 190° the reaction commences, carbonic anhydride and sulphuretted hydrogen being evolved. At a higher temperature the mixture enters into ebullition, and in about half an hour swells to a solid mass. The retort is now reversed, and the contents strongly heated; they melt, boil, and yield a semi-solid distillate. The distillation is carried on as far as possible without charring the residue, which consists of potassium benzoate, from which half the benzoic acid employed may be covered. By addition of ammonia to the semi-solid distillate the acid is retained, whilst the nitrile distils with the water, from which it is afterwards separated, dried, and re-distilled. A roughly carried out experiment yielded 80 per cent of the theoretical quantity of nitrile in a perfectly pure condition; the loss owing to secondary reactions is amply compensated by the ease and rapidity of the operation.

Action of Cuminic Acid on Potassium Sulphocyanate.

An experiment with cuminic acid yielded very satisfactory results: cumonitrile was obtained in about the same proportions as the benzonitrile. The temperature at which reaction commenced was here about 211; the nitrile was purified as in the preceding case.

Finally, an experiment was made with cinnamic acid; but although sulphuretted hydrogen was evolved, and the reaction appeared to proceed quite as in the foregoing cases, no tubuli was obtained in the liquid distillate. The cinnamic acid seemed to be decomposed into carbonic anhydride and cinnamol before becoming acted upon by the sulphocyanic acid.

The ease with which so many nitriles and amides are obtained, both in the aromatic and fatty series, induces me to hope that the new method may be of use in many cases, and perhaps by its application to other series give rise to bodies hitherto uninvestigated.

The tediousness of preparing the acid chloride, and subsequent treatment with ammonia (for the amide) or phosphoric anhydride (for the nitrile) in the ordinary method for producing these nitrogen compounds, is here replaced by simple digestion of the acid with sulphocyanate of potassium, bodies generally readily procurable.


THE sixth and concluding lecture of the course to working men, by Mr. W. W. Smyth, F.R.S., delivered on Monday evening, December 16, was on "The Ores of Iron and their Various Modes of Occurrence."

The lecturer commenced by drawing attention to the vast importance of the iron trade to the well-being of this country, the yield of ore during last year being no less than 17,000,000 tons. The percentage composition of some of the principal iron ores was given as under :Magnetic iron ore-Fe 724, O 276; specular iron ore, or red peroxide of iron-Fe 70, 0 30; brown iron ore, or hydrated oxide of iron-Fe 60 O 26, H2O 14; sparry iron ore, or carbonate of iron-FeO 62, CO2 38.

Magnetic iron ore, or "magnetite," received its name in early times from its magnetic properties. These the lecturer illustrated by means of a magnetic needle, a mass of the ore influencing the needle at a great distance. The magnetism of the ore was shown to be polar, the same side which repelled one end of the needle attracting the other, and vice versa with the other side. It crystallises in the cubical system, the octahedron and rhombic dodecahedron being common forms. It occurs in Sweden, Norway, the Ural Mountains, &c., and on a very much smaller scale in England. In the south-east corner of

Dartmoor, a band of this kind of ore deranges a compass as it is carried past its vicinity, and sailors say that there is a place in Cardigan Bay, where on passing a reef of rocks the needle is influenced, and set oscillating. A large mass of this deposit in the south-east extremity of the Island of Elba has a similar effect; in Sweden, too, deposits are discovered by means of this property. Meteorites frequently contain a percentage of iron greater than magnetite, associated with nickel and chrysolite in some cases, but the rarity of their occurrence precludes them from being classed as iron ores, by which term we understand a mineral containing iron in sufficient quantity as to be economically and advantageously extracted. Specular iron ore occurs in this country on a far larger scale than the preceding variety, the greater proportion of which (either as ore or metal) we have to import from Sweden. The crystalline form of this ore belongs to the hexagonal system, the crystals being, as a rule, tabular. It occurs usually of a bluish black colour, sometimes a brownish red, at others with an iridescent film; while large crystals (as some of these from Brazil) occur occasionally with a lustre so great as to have obtained for it the name of specular or looking-glass ore. But the bulk of the ore, as found in this country has a rounded or mammilated form, and hence is known as "kidney ore," while from its deep rich red colour in some varieties, it is known as hæmatite, or blood-stone. These ores may be readily distinguished from the magnetic by their giving in all cases a red powder when scratched or powdered, whereas the magnetic always give a black powder. They occur especially in the northern districts of England, the districts of Furness and West Cumberland being notably rich. The produce of the mines in those districts for last year was Furness, 931,000 tons; Cleator, 976,874 tons; Hodbarrow, 207,146 tons; making a total of 2,115,000 tons, the value of which as ore being, in round numbers, £2,500,000. It likewise occurs in the Island of Elba (notably round Rio, where many of the rocks quite spangle in the sun with scales of this ore), Bilbao in Spain, Saxony, and North America.

The brown ore, or hydrated oxide, is distinguished from the other varieties by giving a brown powder, and this whatever its external appearance. The quantity of water varies considerably; it is usually from 10 to 15 per cent. It is driven off by a process of calcination-in other words the ore is roasted. It occurs chiefly in our western mining districts, South Wales, and the Forest of Dean. In some cases it occurs in irregular cavities in the strata, with the appearance of having been deposited in them much in the manner of stalactites. The stratified deposits of this ore, occurring in strata belonging to the secondary formation in the midland counties, have only lately had much attention devoted to them, but they will probably come more and more into play as the deposits of superior ore fall away. The town of Middlesborough, and those in its neighbourhood, owe their rapid rise and development entirely to valuable deposits of these oresCleveland ores-discovered a few years ago in the neighbourhood.

Spathose, or sparry iron ore, known as "white iron" ore by the miners on accout of its light colour, is generally found mixed with carbonates of lime, magnesia, &c. Some rhombohedral crystals are found of a pale yellow colour, though the general colour of it varies considerably. It occurs in marked abundance in England, and also in Germany, Austria (at Styria it has been worked for many hundred years), and other places. In England its principal mode of occurrence is in the form of nodules, mixed with much clay, whence the term "clay ironstone." It is found in beds or layers, interstratified

with the various strata of the coal measures. The

nodules contain in some cases as much as 30 per cent of the metal; when split they frequently present patterns of crystallised substances, which have been introduced into the mass by infiltration, and deposited in the cracks which have been formed in the mass by shrinkage. "Black

band" iron ore is a variety of argillaceous ore which has of late years been employed in Scotland; it owes its colour to associated carbonaceous matters, which prove of great use in calcination by diminishing the supply of extra fuel required.

There is one more mineral which is important as yielding iron, but which has only lately been utilised for the purpose, being formerly thrown away as worthless. This is iron pyrites, a compound of iron and sulphur. When, in 1840, the King of Sicily partially prohibited the export of sulphur from that island, the attention of chemists was directed towards this mineral, with the hope of extracting that material from it. Even after means were found for doing this, the remainder still remained unemployed till at length means were discovered which enabled us to obtain not merely the iron, but also to extract a small proportion of copper, and also a minute quantity of silver which occurs in the mineral. Large quantities are obtained from Ireland and from Spain and Portugal.


By CHARLES A. CAMERON, M.D., Professor of Hygiene, Royal College of Surgeons, Ireland; Analyst to the City and County of Dublin, &c.

A SPRING situated at Portobello, a suburb of Dublin, has been for many years in some repute as a sulphur spa, and wonderful cures have been attributed to the use of its waters. I have recently analysed it on behalf of the local authorities, and its composition is so peculiar that I think it worth while to publish it. An imperial gallon contains-Solid matters (chiefly calcic carbonate), 24°236 grains; chlorine, III grains; organic nitrogen, 0·0035 grain; organic carbon, 126 grains; ammonia, 0.562 grain; hydric sulphide (all, except a trace, combined with ammonia), 0'406 grain; nitrites and nitrates, faint traces. Five gallons, evaporated nearly to dryness, gave a remarkable jelly-like residue. The water is clear, of a very light yellowish green colour, and has an odour of sulphuretted hydrogen, which passes away after an hour or two. Only minute quantities of iron and silica are present, and there are no sulphides, except the ammonic sulphide.

There is nothing in the water to account for its reputed medicinal qualities; but the enormous amount of ammonia which it contains, when compared with the minute quantity of albumenoid nitrogen, is very remarkable.

ON SOIL ANALYSES AND THEIR UTILITY.* By EUG. W. HILGARD, State Geologist of Mississippi.

IN the American Journal of Science for September, 1861, Prof. S. W. Johnson published a criticism on the "SoilAnalyses of the Geological Surveys of Kentucky and Arkansas," whose strictures, to a great extent eminently just, appear to have so impressed the scientific public in been made in connection with any state or national survey, this country, that few if any soil-analyses have since then excepting that of the State of Mississippi, where the work already begun was continued, either by myself, or under self responsible for this departure from the generally my charge, or recommendation, by others. Holding myadopted views, I propose in the present paper to discuss specially Prof. Johnson's objections, and to give my reasons for persisting in a course of research that has, more than once, secured for myself and my co-labourers

*Read at the Dubuque Meeting of the Am. Assoc. Adv. Sci, August, 1872.

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