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Scientific American Supplement, No. 841, February 13, 1892 online

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and been ground and splintered in a manner that could not have been
without great crushing force. It would be reasonable enough to suppose
that the action of the river may have uncovered this flint by washing
away the softer material since the occupation of the older race.

In relation to the Indian interment in the examined mound, I could not
say distinctly whether the Indian burials had been such as to make
them aware of former burials or not, but I think from the thickness of
the clay between the two that they were ignorant of former burials.
The mounds of the modern Indian, so far as my investigations are
concerned, would indicate a more rudely formed structure which would
appear to be an imitation of the older mounds, as they are not
finished with like care nor have they the ulterior structures. - _The
Scientist_.

* * * * *




ACTION OF CAUSTIC SODA ON WOOD.

By M.H. TAUSS.


The researches of the author upon the action which water exerts upon
wood at a high temperature have shown how much of the incrusting
material can be removed without the aid of any reagent.

In connection with the manufacture of cellulose, it is also
interesting to prosecute at the same time experiments with solutions
of the caustic alkalies, in order to study the mode of action upon
both wood and pure cellulose. The manufacture of cellulose has for
many years been an industry, and yet little or nothing from a chemical
point of view is known of the action of caustic soda upon vegetable
fibers.

Braconnot, in 1820, obtained alumina by treating wood with an alkali,
but the first application of wood to the manufacture of paper was due
to Chauchard. By boiling vegetable fibers with caustic lyes, Collier
and Piette obtained cellulose. Again, in 1862, Barne and Blondel
proposed to make cellulose in a similar way, but employed nitric acid
in the place of soda.

The first cellulose made exclusively from wood and caustic soda was
produced at the Manayunk Wood Pulp Works, in 1854, in the neighborhood
of Philadelphia, by Burgess & Watt. The operation consisted in
treating the wood for six hours at a pressure of from six to eight
atmospheres, with a solution of caustic soda of 12° B.

Ungerer noticed that it was sufficient to limit the pressure from
three to six atmospheres, according to the quality of the wood, and
advised the use of solutions containing four to five per cent. of
caustic soda. He employed a series of cylinders, arranged vertically,
in which the wood was subjected to a methodical system of lixiviation.
The same lye passed through many cylinders, so that when it made its
exit at the end it was thoroughly exhausted, and the wood thus kept
coming in contact with fresh alkaline solutions.

According to the account of Kiclaner, the disintegration of wood may
be effected in the following four ways:

1. By heating direct in boilers at a pressure of 10
atmospheres. (See Dresel and Rosehain.)

2. In vertical boilers heated direct or by steam, and kept at
a pressure of from 10 to 14 atmospheres. (Sinclair, Nicol, and
Behrend.)

3. In revolving boilers, maintained at a pressure of 12
atmospheres by direct steam.

4. By means of a series of small vessels communicating with
each other, and through which a lye circulates at a pressure
of six atmospheres. (Ungerer.)

This latter process is preferable to the others.

Researches have also been made by the author in order to ascertain the
loss which wood and cellulose suffer at different temperatures or in
contact with varying quantities of alkali (NaHO).

The following is a _resumé_ of the experiments, giving the loss in per
cent. resulting from a "cooking" of three hours duration:

I. Ordinary pressure:
10 grms. cellulose, with 580 c.c. of caustic
soda solution, sp. gr. 1.09 21.99
10 grms. of soft wood, treated as above 49.19
10 " hard " " " 53.68

II. Pressure of five atmospheres:
10 grms. cellulose, with 500 c.c. caustic soda
solution of sp. gr. 1.099 58.02
10 grms. of soft wood, treated as above 75.85
10 " hard " " " 69.80

III. Pressure of ten atmospheres:
10 grms. of cellulose 58.99
10 " soft wood 81.80
10 " hard " 70.39

IV. Ordinary pressure:
10 grms. of cellulose, with 500 c.c. caustic
soda solution of sp. gr. 1.162 21.88
10 grms. of soft wood 35.45
10 " hard " 46.43

V. Pressure of five atmospheres:
10 grms. of cellulose, with 500 c.c. caustic
soda solution of sp. gr. 1.162 77.33
10 grms. of soft wood 97.13
10 " hard " 91.48

VI. Ordinary pressure:
10 grms. of cellulose, with 500 c.c. caustic
soda solution of sp. gr. 1.043 12.07
10 grms. of soft wood 28.37
10 " hard " 30.25

VII. Pressure of five atmospheres:
10 grms. of cellulose, with 500 c.c. of caustic
soda solution of sp. gr. 1.043 15.36
10 grms. of soft wood 50.96
10 " hard " 55.66

VIII. Pressure of ten atmospheres:
10 grms. of cellulose, with 200 c.c. caustic
soda solution of sp. gr. 1.043 20.28
10 grms. of soft wood 70.31
10 " hard " 65.59

From this it is evident that by increasing the temperature and
pressure the solvent action of the alkali is increased, but the
strength of the lye exercises an influence which is even more marked.
Thus, at a pressure of five atmospheres, the loss of cellulose was
0.75 with a caustic lye containing 14 per cent. of NaHO, while it was
only 0.05 with a lye of 8 per cent. NaHO.

To further elucidate the action of the alkali under the conditions
given above, the author has estimated the amount of precipitate which
alcohol gives with the soda solutions, after boiling with the wood:

1. 2. 3.
Specific gravity of NaHO solutions 1.043 1.09 1.162
Soft wood, ordinary pressure 1.043 traces 4.8
" pressure of five atmospheres 1.043 2.0 26.8
" " ten " 1.043 1.7 -
Hard wood, ordinary pressure 11.10 27.40 30.80
" pressure of five atmospheres 1.10 25.70 15.8
" " ten " traces 5.20 15.8

The estimation of the precipitate, produced in the soda solutions
employed in the experiments cited above, gives:

Soft wood, ordinary pressure 1.31 traces 2.0
" pressure of five atmospheres 15.94 16.0 24.80
" " ten " 17.00 25.4 -
Hard wood, ordinary pressure 5.40 6 5.60
" pressure of five atmospheres 9.40 15.40 33.60
" " ten " 14.00 18.40 33.60

As a general rule manufacturers employ a greater pressure than that
which was found necessary by the author. As a result, it appears from
these experiments that the wood not only loses incrusting matter, but
that part of the cellulose enters into solution. As a matter of fact,
the yield obtained in practical working from 100 parts of wood does
not exceed 30 to 35 per cent. - _Le Bull. Fab. Pap.; Chemical Trade
Journal._

* * * * *




NEW BORON COMPOUNDS.


An important paper is contributed by M. Moissan to the current number
of the _Comptes Rendus_, describing two interesting new compounds
containing boron, phosphorus, and iodine. A few months ago M. Moissan
succeeded in preparing the iodide of boron, a beautiful substance of
the composition BI_{3}, crystallizing from solution in carbon bisulphide
in pearly tables, which melt at 43° to a liquid which boils
undecomposed at 210°. When this substance is brought in contact with
fused phosphorus an intense action occurs, the whole mass inflames
with evolution of violet vapor of iodine. Red phosphorus also reacts
with incandescence when heated in the vapor of boron iodide. The
reaction may, however, be moderated by employing solutions of
phosphorus and boron iodide in dry carbon bisulphide. The two
solutions are mixed in a tube closed at one end, a little phosphorus
being in excess, and the tube is then sealed. No external application
of heat is necessary. At first the liquid is quite clear, but in a few
minutes a brown solid substance commences to separate, and in three
hours the reaction is complete. The substance is freed from carbon
bisulphide in a current of carbon dioxide, the last traces being
removed by means of the Sprengel pump. The compound thus obtained is a
deep red amorphous powder, readily capable of volatilization. It melts
between 190° and 200°. When heated _in vacuo_ it commences to
volatilize about 170°, and the vapor condenses in the cooler portion
of the tube in beautiful red crystals. Analyses of these crystals
agree perfectly with the formula BPI_{2}. Boron phospho-di-iodide is a
very hygroscopic substance, moisture rapidly decomposing it. In
contact with a large excess of water, yellow phosphorus is deposited,
and hydriodic, boric, and phosphorus acids formed in the solution. A
small quantity of phosphureted hydrogen also escapes. If a small
quantity of water is used, a larger deposit of yellow phosphorus is
formed, together with a considerable quantity of phosphonium iodide.
Strong nitric acid oxidizes boron phospho-di-iodide with
incandescence. Dilute nitric acid oxidizes it to phosphoric and boric
acids. It burns spontaneously in chlorine, forming boron chloride,
chloride of iodine, and pentachloride of phosphorus. When slightly
warmed in oxygen it inflames, the combustion being rendered very
beautiful by the fumes of boric and phosphoric anhydrides and the
violet vapors of iodine. Heated in contact with sulphureted hydrogen,
it forms sulphides of boron and phosphorus and hydriodic acid, without
liberation of iodine. Metallic magnesium when slightly warmed reacts
with it with incandescence. When thrown into vapor of mercury, boron
phospho-di-iodide instantly takes fire.

The second phospho-iodide of boron obtained by M. Moissan is
represented by the formula BPI. It is formed when sodium or magnesium
in a fine state of division is allowed to act upon a solution of the
di-iodide just described in carbon bisulphide; or when boron
phospho-di-iodide is heated to 160° in a current of hydrogen. It is
obtained in the form of a bright red powder, somewhat hygroscopic. It
volatilizes _in vacuo_ without fusion at a temperature about 210°, and
the vapor condenses in the cooler portion of the tube in beautiful
orange colored crystals. When heated to low redness it decomposes into
free iodine and phosphide of boron, BP. Nitric acid reacts
energetically with it, but without incandescence, and a certain amount
of iodine is liberated. Sulphuric acid decomposes it upon warming,
without formation of sulphurous and boric acids and free iodine. By
the continued action of dry hydrogen upon the heated compound the
iodine and a portion of the phosphorus are removed, and a new phosphide
of boron, of the composition B_{5}P_{3}, is obtained. - _Nature_.

* * * * *




BORON SALTS.


A paper upon the sulphides of boron is communicated by M. Paul
Sabatier to the September number of the _Bulletin de la Societe
Chimique. Nature_ gives the following: Hitherto only one compound of
boron with sulphur has been known to us, the trisulphide, B_{2}S_{3},
and concerning even that our information has been of the most
incomplete description. Berzelius obtained this substance in an impure
form by heating boron in sulphur vapor, but the first practical mode
of its preparation in a state of tolerable purity was that employed by
Wohler and Deville. These chemists prepared it by allowing dry
sulphureted hydrogen gas to stream over amorphous boron heated to
redness. Subsequently a method of obtaining boron sulphide was
proposed by Fremy, according to which a mixture of boron trioxide,
soot, and oil is heated in a stream of the vapor of carbon bisulphide.
M. Sabatier finds that the best results are obtained by employing the
method of Wohler and Deville. The reaction between boron and
sulphureted hydrogen only commences at red heat, near the temperature
of the softening of glass. When, however, the tube containing the
boron becomes raised to the temperature, boron sulphide condenses in
the portion of the tube adjacent to the heated portion; at first it is
deposited in a state of fusion, and the globules on cooling present an
opaline aspect. Further along the tube it is slowly deposited in a
porcelain like form, while further still the sublimate of sulphide
takes the form of brilliant acicular crystals. The crystals consist of
pure B_{2}S_{3}; the vitreous modification, however, is usually
contaminated with a little free sulphur. Very fine crystals of the
trisulphide may be obtained by heating a quantity of the
porcelain-like form to 300° at the bottom of a closed tube whose upper
portion is cooled by water. The crystals are violently decomposed by
water, yielding a clear solution of boric acid, sulphureted hydrogen
being evolved. On examining the porcelain boat in which the boron had
been placed, a non-volatile black substance is found, which appears to
consist of a lower sulphide of the composition B_{4}S. The same
substance is obtained when the trisulphide is heated in a current of
hydrogen; a portion volatilizes, and is deposited again further along
the tube, while the residue fuses, and becomes reduced to the
unalterable subsulphide B_{4}S, sulphureted hydrogen passing away in
the stream of gas.

Two selenides of boron, B_{2}Se_{3} and B_{4}Se, corresponding to the
above described sulphides, have also been prepared by M. Sabatier, by
heating amorphous boron in a stream of hydrogen selenide, H_{2}Se. The
triselenide is less volatile than the trisulphide, and is pale green
in color. It is energetically decomposed by water, with formation of
boric acid and liberation of hydrogen selenide. The liquid rapidly
deposits free selenium, owing to the oxidation of the hydrogen
selenide retained in solution. Light appears to decompose the
triselenide into free selenium and the subselenide B_{4}Se.

Silicon selenide, SiSe_{3}, has likewise been obtained by M. Sabatier
by heating crystalline silicon to redness in a current of hydrogen
selenide. It presents the appearance of a fused hard metallic mass
incapable of volatilization. Water reacts most vigorously with it,
producing silicic acid, and liberating hydrogen selenide. Potash
decomposes it with formation of a clear solution, the silica being
liberated in a form in which it is readily dissolved by alkalies.
Silicon selenide emits a very irritating odor, due to the hydrogen
selenide which is formed by its reaction with the moisture of the
atmosphere. When heated to redness in the air it becomes converted
into silicon dioxide and free selenium.

* * * * *




NATURAL SULPHIDE OF GOLD.

By T.W.T. ATHERTON.


The existence of gold in the form of a natural sulphide in conjunction
with pyrites has often been advanced theoretically as a possible
occurrence, but up to the present time this occurrence has, I believe,
never been established as an actual fact.

During my investigations on the ore of the Deep Creek Mines, I have
found in them what I believe to be gold existing as a natural
sulphide. The description of this ore will, no doubt, be of interest
to your readers.

The lode is a large irregular one of pure arsenical pyrites, existing
in a felsite dike near the sea coast. Surrounding it on all sides are
micaceous schists, and in the neighborhood is a large hill of granite
about 800 ft. high. In the lode and the rock immediately adjoining it
are large quantities of pyrophylite, and in some places of the mine
are deposits of this pure white, translucent mineral, but in the ore
itself it is a yellow and pale olive green color, and is never absent
from the pyrites.

From the first I was much struck with the exceedingly fine state of
division in which the gold existed in the ore. After roasting and very
carefully grinding down in an agate mortar, I have never been able to
get any pieces of gold exceeding the one-thousandth of an inch in
diameter, and the greater quantity is very much finer than this.
Careful dissolving of the pyrites and gangue, so as to leave the gold
intact, failed to find it in any larger diameter. As this was a very
unusual experience in investigations on many other kinds of pyrites, I
was led further into the matter. Ultimately, after a number of
experiments, there was nothing left but to test for gold as a
sulphide.

Taking 200 grammes of pyrites from a sample assaying 17 ounces fine
gold per ton, grinding it finely, and; heating for some hours with a
solution of sodium sulphide (Na_{2}S_{2}), on decomposing the filtrate
and treating it for gold I got a result at the rate of 12 ounces gold
per ton. This was repeated several times with the same result.

This sample came from the lode at the 140 ft. level, while samples
from the higher levels where the ore is more oxidized, although
carrying the gold in the same degree of fineness, do not give as high
a percentage of auric sulphide.

It would appear that all the gold in the pyrites (and I have never
found any apart from it) has originally taken its place there as a
sulphide.

The sulphide is an analysis of a general sample of the ore:

Silica 13.940 p.c.
Alumina 6.592 "
Lime 0.9025 "
Sulphur 16.584 "
Arsenic 33.267 "
Iron 27.720 "
Cobalt 0.964 "

Per Ton.
Nickel Traces.
Gold 5 ozs. 3 dwts. 8 grs.
Silver 0 " 16 " 0 "
- - - -
99.969

Nambucca Head's Gold Mining Company, Deep Creek, N.S. Wales, Oct. 9,
1891. - _Chemical News_.

* * * * *




SOME MEANS OF PURIFYING WATER.


There are several methods extant for the purpose of purifying and
softening water, and in the following brief account some of the chief
features of these methods are summarized. The Slack and Brownlow
apparatus we will deal with first. This purifier is one which is
intended to remove the matter in suspension in the water to be treated
by subsidence and not by filtration. The apparatus consists of a
vertical iron tank or cylinder, inside which are a series of plates
arranged in a spiral direction around a fixed center, and sloping at
an angle of 45° on both sides outward. The water to be dealt with
flows through a large inlet tube fixed to the bottom of the cylinder,
rises to the top by passing spirally round the whole circumference,
and depositing on the plates or shelves all solids and impurities at
the outer edges of the plates. Mud cocks are placed to remove the
solids deposited during the flow of the water upward to the outlet
pipe, placed close to the top of the cylinder. One of these tanks, a
square one, is at work purifying the Medlock water at Manchester, and
on drawing samples of water from nearly every plate, that from the
lower mud cock showed considerable deposit, which decreased in bulk
until the top mud cock was reached, when the water was quite free from
deposit. It is stated that one man would be sufficient to attend to 20
of these purifiers.

To filter or purify 2,000,000 gallons per 24 hours would require 40
tanks, 10 ft. by 7 ft. diameter, each doing 2,000 gallons per hour,
and would cost, with their fittings, £6,400, including all patent
rights, but exclusive of lime mixing tanks, agitators, lime water and
softening tanks, engine and boiler, and suitable buildings, the cost
of which would not be far short of £5,000, or a total of £11,400 to
soften 2,000,000 gallons per 24 hours. The labor and other working
expenses in connection with this plant would not be less than that
necessary to work the Porter-Clark process, which is given as O.55d.
per 1,000 gallons.

The Brock and Minton filter press system is another method. This
patent press is made of steel, perforated with ½ inch holes. On the
inside of the shell there is first laid a layer of fine wire netting,
then a layer of cloth, and lastly another layer of wire netting of a
larger mesh than the other. The matter treated is pumped into the body
of the cylinder, the liquid passing through the filtering material to
the outside, the solids being retained inside, and are got rid of by
partially revolving the upper half to relieve it from the knuckle
joint, and, after being raised, the lower half is turned over by
machinery, and the solid matter is simply allowed to fall out into
wagons or trucks run underneath for that purpose. Such, in brief, is
the manner of using this filter press for chemical works' purposes.
The cost of each filter press, including royalties, is from £250 to
£300, the size being 8 ft. by 4 ft. diameter. Having a filtering area
of 100 square feet, it would require 32 of these applied to softening
water to effectually deal with 2,000,000 gallons per 24 hours; this,
at the lowest estimate for filters alone, would be £8,000, and, using
the same figures, £5,000 for lime mixing tanks, etc., as referred to
in the "Slack and Brownlow" purifier, would bring the total cost up to
£13,000, and the working expense would not be less than that required
to work the Porter-Clark process, and would probably be very much
greater. This filter press is not in use anywhere for dealing with
large quantities of water in connection with a town water supply.

A process which has been working for a long time at Southampton is the
Atkins system, which also includes the use of filter presses. The
pumping station and softening works are situated at Otterbourne, eight
miles from Southampton, and were built together as one scheme. The
mixing room has two slaking lime tanks, with agitators driven by steam
power. The mixture is then run as cream of lime into a tank 20 ft.
square and is then pumped into the lower ends of two lime water
producing cylinders. The agitation is here obtained by pressure from a
small cistern placed above them with a 12 ft. head, the pipe from
which is attached to the lower ends of the cylinders. This has been
found by experiment to be the most satisfactory means of obtaining the
proper degree of agitation necessary; the clear lime water is then
drawn off at the top of the cylinders, and flows by gravity into a
mixer, where it comes in contact with the hard water. Both flow
together into a distributing trough, from which it overflows into a
small softening reservoir, having a capacity of one hour's supply, a
weir being placed along the lower end, over which the water flows to
13 filter presses. The clear water from the filters is then conveyed
to a small well, from which the permanent engines raise it to the
first of a series of high level covered service reservoirs.

In the filter press there are 20 hollow disks representing a filtering
area of 250 square feet, or a total of 3,250 square feet. The water to
be filtered passes into the body of the filter and then through a
filtering medium of cloth laid on a thin perforated zinc plate, into
the inner side of the disks, from whence it is conveyed through the
hollow shaft, to which the disks are attached, to the high level
pumps.

The filter cloths are cleaned three times every 24 hours, without
removal, by jets of softened water from the main, having a pressure of
60 pounds to the square inch. During cleaning operations the disks are
made to revolve slowly; this only occupies a space of five minutes for
each cleaning. The cloths last from six to eight months without being
renewed. They also occasionally use for further cleaning the cloths a
jet of steam injected upon the center of the disks in order to remove


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Online LibraryVariousScientific American Supplement, No. 841, February 13, 1892 → online text (page 10 of 11)