ON THE ESTIMATION OF SULPHUR IN IRON present in the solution, it must be evaporated to dry

AND ITS MINERALS.*

BY M. W. EGgertz,

PROFESSOR AT THE FAHLUN MINING SCHOOL.

As small quantities of sulphur, even a few tenthousandths, are sufficient to render iron, even of excellent quality, red-short and unfit for certain uses, it would be very useful to be able to ascertain the quantity of sulphur which exists in the iron, not only with the necessary scientific exactness, but also with a facility and accuracy suitable for practical wants. But as the methods ordinarily employed for this purpose, especially on the score of facility, leave much to be desired, I have been engaged for several years in improving the known processes, and I wish to communicate in these pages the results of my researches. I have found in this difficult work, especially in the estimation of sulphur in iron analytically, useful aid on the part of M. J. E. Sieurin, and some other students of the Mining School, but I must especially mention the valuable services of M. J. F. Lundberg.

A. Detection of sulphur by means of chloride barium.

of

1. Iron.-5 grammes of iron passed through a sieve with apertures of o'6 m.m., are added to a solution of 10 grammes of pure chlorate of potash, free from sulphate, in 200 cubic centimetres of distilled water, and Cover contained in a flask of a capacity of 500 c.c. this flask with a small funnel and heat the contents on a sand-bath to complete ebullition; then add gradually 60 c.c. of hydrochloric acid of the specific gravity 112. It is best to add the hydrochloric acid at first drop by drop from a burette, as otherwise a strong disengagement of gas would take place; but in proportion as this evolution diminishes larger quantities of acid may be added; ordinarily half an hour is required for this operation, and during this time the solution ought to be kept in complete ebullition, so that no sulphuretted hydrogen gas escapes. Then allow the liquid to In this way boil gently for five or six minutes more. the carbon and part of the silicic acid remain insoluble, and often also a brown flocculent or pulverulent substance resembling hydrated oxide of iron, which is composed of a geic product analogous to humus, which is formed from the carbide of iron. During the solution a little sulphur is also sometimes separated; it swims on the surface. To oxidise this sulphur and drive off the chlorine and hydrochloric acid which are

* Moniteur Scientifique.

ness in a water-bath; the sides of the flask and the small funnel which covers it should always be first well washed with a jet of distilled water.

If there is much sulphur on the surface the moment it has disappeared the funnel should be replaced by a When the solution has become syrupy paper cover. the desiccation should be hastened by stirring it well with a glass rod. Add to the dry mass 10 c.c. of hydrochloric acid and 30 c.c. of water, and then leave the mixture on the water-bath until all the crystals of chloride of iron are dissolved, then add about 20 c.c. more water, and collect the insoluble portion on a filter, washing it perfectly with warm water. It sometimes happens that during the washing the organic matters remaining on the filter dissolve and precipitate again in contact with the acid solution, but they are easily redissolved on boiling the liquid. The last washing water ought to have no acid reaction; evaporated and heated to redness on platinum foil it should leave no trace of residue.

The filtered liquid, whose volume is about 50 c.c., should be rapidly boiled and mixed with 2 c.c. of a saturated solution of chloride of barium. (This amount is sufficient to precipitate the sulphuric acid formed from o'i grm, of sulphur). After cooling add to the The mixture 5 c.c. of ammonia sp. gr. o'95, then stir well with a glass rod, and leave the whole to rest at the ordinary temperature for twenty-four hours. clear solution should be decanted as completely as possible on to a strong filter, and the precipitate stirred up with about 20 c.c. of cold water, and then left to itself until it has quite settled. If warm water is used without having added a few drops of hydrochloric acid, a little oxide of iron will precipitate. The clear liquid is likewise thrown on to the filter, and the operation is repeated several times with cold water, and then two or three times with boiling water, with' out which precaution the sulphate of baryta will pass through the filter. Finally collect the precipitate, and wash it carefully with warm water. The last drops of this water on being evaporated on a watch-glass ought not to leave more than a scarcely visible white ring. The precipitate is then dried, heated to redness, and weighed. If it is coloured with oxide of iron it must be washed with a little hydrochloric acid, dried in the water-bath, and taken up with a few drops of acid and water, and then the preceding operations repeated (washing, drying, heating, and weighing). If the precipitate has only a feeble red colour, which is often the case, this latter operation will be unnecessary.

100 parts of sulphate of baryta contain 34'3 parts of

2

On the Manufacture of Glass.

experiment 5 grms. of iron have been used, each 0.001 grm. of sulphate of baryta will correspond to o'00274 per cent. of sulphur in the iron.

ON THE MANUFACTURE OF GLASS.
BY HENRY CHANCE, M.A.

July, 1868.

or less alumina, and it has been noticed that the outer portions next the crucible often show irregularities, and occasionally some coarse gritty particles become detached from the inner surface by corrosion of the finer clay under the action of the fused alkali. Chloride of sodium excepted, no appreciable amount of alkali is lost by volatilisation in the furnace; at any rate, the deficiency from all sources of waste, including the mix

Abstract of a Lecture delivered at the Chemical Society, ing, decrepitation on first heating, &c., never exceeds 1

March 19th, 1868.

REFERRING to the raw materials of which glass is
made, the various qualities of sand were in the first
place described. The American sand is considered the
finest of all; then that from Fontainebleau; Belgian
next; and, of English samples tolerably free from iron,
the deposits occurring at Leighton Buzzard were in
great demand. This quality is, indeed, almost exclu-
sively employed by the Messrs. Chance, and, though
of a yellowish tint, contains less iron than many whiter
samples. Sand of a strong reddish hue may be made
nearly white by calcining it with a small quantity of
The Welsh sand is not held of much
common salt.
account, for it seems to produce glass in which striæ
abound.

With respect to the alkaline ingredients for glass-
making the use of kelp, soda of alicant, and Egyptian
natron, were briefly noticed, and the influence of Le
Blanc's discovery traced. The substitution of the sul-
phate for the carbonate of soda-due to Gehlen-tended
to cheapen the glass, but at the sacrifice of quality; for
the best kinds of plate glass the carbonate (soda ash)
is always employed. For the common blown window
glass the sulphate answers well: it will permit the use
of larger charges of lime, and the glass produced from
it is harder, takes a better polish, is less liable to devi-
trification, and to the alteration of its surface by what
is termed "sweating." The addition of carbon in the
form of charcoal, or powdered anthracite, facilitates
the reduction of the sulphate, and tends to promote
vitrification. Only one atom of carbon is, in practice,
found sufficient for two atoms of sulphate of soda. The
object of its employment would, then, seem to consist
in furnishing the means of reduction of a part only of
the alkaline sulphate to the state of sulphite, and not
to sulphide; the decomposition of the sulphate is fur-
ther facilitated by a liberal use of carbonate of lime,
the action of which is not clearly intelligible. Glass
made from sulphate of soda is of a bluish, whilst that
made from the carbonate is of a yellowish tint. When
an extra pale colour is desired, the carbon is kept at a
minimum, and the lecturer once saw, at glass works in
the north of France, an expedient practised in this di-
rection, which consisted in employing the sulphate in
large excess, and ladling off the upper layer of this
fused salt whilst the pots stood in the furnace. Should
any of this ingredient be accidentally left in the cruci-
ble, salt-blisters" are formed.

66

The lime required for the crucible charges is introduced in the form of quick-lime when carbonate of soda glass is made; but for the other kind either chalk or limestone, preference being given to the latter, probably on account of its containing some carbonate of magnesia. This addition of lime is in flint glass replaced by oxide of lead, giving great lustre and refracting power, but if made into sheet would be full of striæ. Pipe clay and alumina are sometimes used in glass-making, but are not supposed to improve the quality; all glass fused in clay pots must necessarily contain more

per cent.

The average composition of different qualities of glass was stated to be as follows:

The use of peroxide of maganese and arsenious acid in glass-making is mainly for the purpose of effecting the peroxidation of the iron, which in this state has far less colouring property. The author here pointed out as an anomaly the circumstance of carbon and metallic oxides being employed in the same mixture, but an attempt to defer the addition of the latter until the carbon had done its work was only partially successful, since it is difficult in the last stages to insure a proper incorporation of the materials. The Belgian manufacturers are said to have discontinued the use of the above The purest coloured flint glass is metallic oxides. composed of sand, potash, and oxide of lead. For some kinds of optical glass a portion of the red lead is replaced by lime, and if the lead is used in excess the heavy flint glass produced has a strong yellowish tint. When much manganese is employed to correct the colour arising from- impurities in the glass mixture, there is a tendency for the glass to undergo changes of colour on exposure to sunlight; and a greenhouse roofed with glass in which manganese has been used will often display, after a lapse of time, a great variety of Reference was then made to Mr. Gaffield's tints. experiments on the action of sunlight upon glass, and to the practical conclusion arrived at, to the effect that the alteration in colour was solely due to the different states of oxidation of the manganese. The lecturer further asserted that he had noticed changes of colour in glass which did not contain a trace of this metallic oxide, and specimens were exhibited in which the glass, originally white, had become strongly tinged with yellow. In connection with the employment of Siemen's regenerating furnaces at his works, Mr. Chance stated the following particulars. The cubical capacity of the glass furnace was about 1800 feet (or 20 feet long, 10 broad, and 9 feet high). This chamber accommodated eight large clay melting-pots, each of which was capa

CHEMICAL NEWS, Test for Bromides.-On the Chemistry of the Bessemer Process.

July, 1863.

ble of producing two tons of refined glass in five and
twenty hours. The saving on Siemen's plan was, first-
ly, the difference in cost between large coal and slack;
and, secondly, a more cleanly manipulation, whereby a
superior product was obtained in open pots. By way
of conclusion the lecturer described Gossage's process
for the manufacture of soluble glass, and the results of
A
his own experiments on the fusion and devitrification
Rowley Rag."
of the basaltic rock known as
large slab of the fused material, which is similar to black
marble, and other specimens of the same devitrified,
were exhibited.

TEST FOR BROMIDES.

BY SURGEON J. H. BILL, U. S. ARMY.

IN conducting some investigations during the past summer, on the physiological relations of the halogens, it became absolutely necessary in the course of the experiments, to devise a ready and sensitive test for bromine in the presence more particularly of chlorine. Any analyst will bear out the assertion-although the books make light of the matter that it is a difficult thing to recognise traces of bromine in the presence of excess of the other halogens. Thus in the case stated above, it was found impossible to obtain by the ordinary methods of the books, a certain and easy recognition of bromine when chlorine was present.

The Fresenius test solution of auric chloride produces in faintly acid solutions of alkaline bromides, a colouration ranging from dark orange red to light straw colour, according to the strength of the solution. Iodides must be out of the way. Chlorides, however, do not interfere in the least. The following is the best way of applying the test:-Separate iodides by palladium, and after getting rid of excess of palladium by sulphuretted hydrogen, concentrate the solution to about twenty-five cubic centimetres. Select two test tubes, of the same size and shape, and colour of glass. Into one pour the solution suspected to contain bromide. Into the other pour pure water, adding perhaps a trace of chloride potassium; add now to each test tube a drop of chlorhydric acid, and then to each one drop of auric chloride solution. On now comparing the two tubes particularly in the direction of their long axes, a yellow colour will be observed in the tube containing the bromide, and made very manifest by comparison with the other tube.

The following experiment shows the delicacy of the test applied as above:-One centigramme of potassic bromide was dissolved in one thousand cubic centimetres of water. Thirty centimetres of this solution, compared with thirty centimetres of a very weak solution of potassic chloride, gave a decided yellow colour. This experiment was varied by dissolving a gramme of potassic chloride in two thousand cubic centimetres of water, halving, and adding one centigramme of potassic bromide to the one half. Thirty centimetres of each of the two solutions now tested, gave ample evidence of the presence of bromide.

The mixed chioride and bromide should be brought to the state of salts of the alkalies if necessary, by precipitating with argentic nitrate, thoroughly washing, and fusing with potassic carbonate. If sodic carbonate is used, the subsequent reaction with the gold test is not so decided.

A test for chloride in the presence of bromide, as

3

simple and delicate as the above, is much needed. The
writer has sought long for it but in vain.-Am. Journ.
Science, March, 1868.

ON THE CHEMISTRY OF THE BESSEMER
PROCESS.*

ANALYSES representing each successive step in the
Bessemer process do not appear, as yet, to have been
and the various products at different stages of this pro-
published. The following analyses of the raw material
cess were sent with the manufactured objects to the
late Paris Exhibition from the Bessemer Works of
Neuberg, in Austria. In the absence of more com-
plete analyses, they may be of some value.

The charge was a good dark-grey iron, weighing 62 cwt 80 lbs. (Austrian); it was transferred directly Blast was from the blast furnace into the converter. applied for 28 minutes under a pressure of 20 lbs. to the inch; at the close of this first period a sample of the iron was taken. During the second period, of 7 minutes, the pressure of the blast was 18 to 19 lbs. per square inch; the third period lasted only 3 minutes, under about the same blast. The amount of slag was The analyses of the a little larger than usual, probably because of the taking of samples from the mass. raw-iron and of the samples taken at the close of the above period, gave the following results:

1. The iron taken was dark-grey, graphitic, containing considerable silicon, very little phosphorus and sulphur, and much manganese; in every respect an excellent material for the Bessemer process. A small amount of copper was present, but not enough to either hinder the process or deteriorate the product.

2. At the close of the first period spoken of, all graphite had disappeared, partly by combustion, partly by combination with the iron; almost four-fifths of the silicon had been separated; all but a trace of sulphur had disappeared; the amount of phosphorus remained nearly the same; also the total amount of the copper, while its percentage was a little higher; much of the manganese was lost. The product at the close of this period was a pure white raw-iron, containing not overmuch of carbon.

3. During the second period the removal of the carbon progresses rapidly, so also the still remaining are rapidly disappearing,. silicon and manganese the same. The product at the close of this period while again the copper and phosphorus remain almost of only about seven minutes was a good steel; according to the common scale, steel No. 3.

4. At the close of the third period, a steel No. 7 was obtained. The addition of 6 cwts. raw iron gave a Bessemer steel No. 6.

The slags obtained at the various stages were also analysed; they always contained a great relative amount of silica, but, both before and after the second (or "boiling ") period, remarkably little of ferrous oxide. During the last stages of the process, the percentage of manganese in the slag decreases, because most of the manganese is removed in the first A little period, so that the increase of slag during the last stages of the process can only add iron to it, i. e., reduce the percentage of the manganese. alumina and lime found in the slag is ascribed to the walls of the furnace.

*"Aus der Natur," 1867, p. 714, &C.

NEWS

July, 1865

From the composition of the raw material and the final product, the amount of the various elements removed during the process is obtained by the difference of the first two quantities. The amount of oxygen necessary for this removal may easily be calculated on the supposition that the silicon is converted into silica, carbon into carbonic acid (CO), phosphorus to phosphoric acid (anhydride), sulphur to SO2 or SO,; iron to magnetic oxide (Fe3O4), of which but a small amount is found in the slag, the greatest portion being blown out in the shape of a red smoke (Fe2O). The following table contains the results thus obtained:

GRAPHITE IN CALIFORNIA.

THE principal plumbago deposit of California, known as the Eureka Black Lead Mine, is situated on the west side of Tennessee Gulch, a tributary of Wood's Creek, about 1 miles from Sonora, the county seat of Tuolumne county, and about 68 miles from Stockton, the head of navigation on the San Joaquin River. The mineral exists as a well-defined lode, from 20 to 30 feet wide, having a dioritic foot-wall on the west, and a soft clay-slate hanging wall on the east. The trend of this lode is nearly north-east by south-west, and it dips very irregularly to the east, at some places being nearly vertical, and at others nearly horizontal. It has been traced and explored for 3,900 feet, beyond which there are but faint indications of its existence. The whole deposit, including the walls and vein, is enclosed in the limestones peculiar to Tuolumne and the adjoining counties.

The graphite near the surface is much contaminated with the materials of the clay-slate, which rapidly decomposes on exposure to the atmosphere. It was this circumstance that delayed the development of the mine, as it was found impossible to separate the earthy matter from the more valuable plumbago. About two years since it was discovered that the graphite floated on water, when a simple apparatus was employed, which separates nearly ioo tons per day, giving em

ployment to some 25 labourers to wheel the stuff from the mine to the arrastre, about 50 feet distant. This separating process is not now required, for in a large portion of the vein below the surface, at a depth of 40 feet, the graphite is cut out in solid blocks, and sacked without any further preparation; but it is divided by lenticular bodies of clay-slate, a few inches thick, and sometimes extended for several feet. This material is heavily charged with graphite, and is washed in order to separate it. At the depth of 60 feet the graphite is exceedingly solid and hard, with a very fine lustre. The whole material is taken out between the walls by an open cutting; all found not absolutely pure is washed, the other is bagged at once.

The product of the mine at present is about 1,000 tons per month, but is capable of an almost indefinite extension. The process of separating the graphite from the impurities is very simple. An inexpensive sort of large vat, with a stone bottom, 20 ft. in diameter, and 3 ft. deep, holds the materials, which are stirred up by iron rakes fastened to four cross-bars projecting from an upright shaft, moved by a waterwheel. When in motion a small stream of water passes into this vat, an outlet to which exists a few inches from the surface; through this outlet the graphite passes with the water, and is led by spouts into broad tanks, where it temporarily subsides, when the dirty water is run off, and a large stream of clean water forces the graphite into a series of shallow tanks, in which it is dried by the sun, the whole process requiring about five days to complete. The tanks and reservoirs at present used cover several acres. cost of production of the solid plumbago at the mine does not exceed 48. per ton, two men in the lower workings being able to extract 10 tons per day of solid graphite, in blocks of any desired size. The water used on the mine costs but £10 per month, which sum is more than realised by gold found in the vat when cleaning up, there being a thin seam of auriferous quartz between the hanging wall and the graphite Occasionally passing into it. Lumps of gold, worth from 8s. to £4 each, are sometimes found imbedded in the graphite.-Dicker's Mining Record.

ON THE

The

EMPLOYMENT OF SAND AND GLASS FILTERS
IN QUANTITATIVE ANALYSIS.

BY WOLCOTT GIBBS, M.D.,

RUMFORD PROFESSOR IN HARVARD UNIVERSITY,

SUFFICIENT att ntion has not been paid to the advantages of filters of sand and glass over those of paper, when precipitates are to be dried upon the filter at a definite temperature. By choking the throat of a funnel with coarse fragments of glass and then placing upon these successive layers of powdered glass or sand, the upper layer being of the finest powder, it is easy to make a filter upon which almost any precipitate may be filtered off and washed out completely without the slightest loss. The funnel with its conten's may then be dried at any temperature below that at which the glass softens or at which the precipitate undergoes chemical or physical change. Mr. E. R. Taylor, who has carried out this suggestion with the greatest care and thoroughness, obtained the following results in three analyses of tai tar-emetic :

I.

July, 1863.

Grm. tartar-emetic.

Grm.

0.0891

=

66

=

36.08
36.07

66

0'0917 gave 00463 Sb2S1 = 36:09 per cent. Sb. II. 06236 0'3149 III. 01766 The formula requires 35'92 per cent. (Sb=120). In the first and second analyses the precipitated sulphide was dried at 375°C. In the third, the funnel had the shape of a tube tapering at one end and dilated in the middle to a sort of bulb, and the precipitated sulphide of antimony, after drying, was ignited in the filter tube itself in a current of carbonic acid gas. This form of funnel, which is due to Mr. Taylor, will be found very advantageous. A small common funnel may be inserted into the top, and after drying, the tube funnel closed with a cork in weighing.-American Journ. Science.

ON THE ESTIMATION OF NITRIC ACID. (PELOUZE'S METHOD.)

BY PHILIP HOLLAND.

Or the various processes from time to time proposed
for the estimation of nitric acid in combination, there
are three which may be said to be in some measure re-
lated, viz., those of Pelouze, Schloesing, and Walter
Crum. In the two first the weighed nitrate is boiled
out of contact with air with a solution of protochloride
of iron and an excess of hydrochloric acid. Under these
conditions the N.Os splits up on the one hand into
oxygen gas which indirectly by depriving the hydro-
chloric acid of its hydrogen admits of the conversion of
the protosalt of iron into a persalt, and on the other into
a lower oxide of nitrogen which escapes. The reaction
being a definite one obviously affords two methods for
estimating nitric acid. We may either determine the
iron oxidised, which forms the basis of Pelouze's pro-
cess, or we may after Schloesing reconvert the nitric
oxide into nitric acid by the addition of oxygen, and
In Crum's
titrate with an alkali in the usual manner.
method the nitrate together with a sufficiency of sul-
phuric acid to decompose it is agitated with mercury,
whereby a reduction is effected with formation of nitric
oxide as in the preceding instance. Of the three pro-
cesses I have enumerated Schloesing's is valuable to the
analyst, whose object it is to determine our acid when
in the presence of organic matter; it does not appear
to have come into general use, this is perhaps to be ac-
counted for by the fact that the operations it involves
are rather tedious, and somewhat difficult of execution.
Since the method of Pelouze is extensively practised, a
description of a simple apparatus for its successful prose-
cution may be interesting. Before I describe my ap-
paratus I will notice the process as it stands at present.
What are its absolute requirements? Two; firstly,
that the decomposition of the nitrate shall take place in
an atmosphere of which oxygen does not form a part,
and secondly that such decomposition shall be complete.
I need not describe the method as set forth in Fre-
senius; it is familiar to all. The author conducts the
operation in a retort, through which he passes a current
of hydrogen. Attached to the stem of the retort is a
U-tube, containing a little water, which serves as a lute
to prevent access of air.

In the modified arrangement I am about to describe,
the operation is conducted in vacuo, and at its termina-
tion the solution is boiled to expel the nitric oxide, thus
avoiding the necessity of employing either hydrogen or
carbonic acid.

In the accompanying sketch, A, is a long-necked assay flask drawn off at B, so as to form a shoulder, over which is passed a piece of French india-rubber tube, D, about 6 centimetres long, the other end terminating in a glass tube, F, drawn off so as to leave only a small orifice. On the elastic connector D is placed a screw compression clamp. At c, a distance of 3 centimetres from the shoulder, is cemented with the blow-pipe a piece of glass tube about 2 centimetres long, surmounted by one of French tube rather more than twice that length. The elastic tubes must be securely attached to the glass by binding with wire. After binding, it is as well to turn the end of the connector back and smear the surface with fused caoutchouc, and then replace it.

This device is recommended by Dr. Sprengel for securing an air-tight joint. The wooden clamp E gives support to the flask; the rest of the arrangement requires no explanation.

The analysis of a nitrate is conducted as follows:-A small funnel is inserted into the elastic tube at c, the clamp at D being for the time open; after the introduction of the solution followed by a little water, which washes all into the flask, the funnel is removed, and the former placed in the inclined position it occupies in the figure. The contents are now made to boil so as to When this point is reached a piece of glass expel all air and reduce the volume of the fluid to about 4 or 5 c.c. the water vapor to find egress through F. rod is inserted into the elastic tube at c, which causes

Into the small beaker is put 50 c.c., more or less, of a previously boiled solution of protosulphate of iron in hydrochloric acid. (The amount of iron already existent therein as a persalt must be known).

The boiling is still continued for a moment to ensure perfect expulsion of air from F, the lamp is then removed, and the caoutchouc connector slightly compressed with the first finger and thumb of the left hand. As the flask cools the solution of iron is drawn into it, when the whole has nearly receded the elastic tube is tightly compressed with the fingers, whilst the sides of the beakers are washed with a jet of boiled water, which is also allowed to pass into the flask. The washing may be repeated, taking care not to dilute more than necessary or admit air. Whilst F is still full of water, the elastic connector previously compressed with the fingers is now securely closed with the clamp, the screw of which is worked with the right hand. Provided the clamp is a good one, F will remain full of water during the subsequent digestion of the flask.

After heating at 100° for half an hour the flask is re