Scientific American Suppl. No. 299
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Various >> Scientific American Suppl. No. 299
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When the reduction has been completed, the supernatant liquid is poured
off, and the residue washed in the ordinary manner.
DETERMINATION OF ARSENIC.
Arsenic cannot be completely separated from either its aqueous
hydrochloric acid, or from a solution to which ammonium oxalate has been
added in excess. From its aqueous as well as from its oxalate solution,
a portion of the metal may be separated, but if the current is passed
through its hydrochloric acid solution for a sufficient length of time,
all the arsenic will be volatilized as arsenious hydride (AsH_3).
SEPARATION OF IRON FROM MANGANESE.
If a solution of ferric oxide and manganese ammonium oxalate is
submitted to electrolysis, without the previous addition of ammonium
oxalate, the characteristic color of permanganic acid immediately makes
its appearance, and the peroxide gradually precipitates itself on the
positive, while the iron is deposited on the negative electrode. When
the examination is made in the above manner, it is impossible to
separate the two metals, for the peroxide will bring down with it a
considerable quantity of ferric hydrate. The separation of the two
metals is only possible when the precipitation of the manganese peroxide
is prevented, until the greater portion of the iron has been deposited.
This result may be attained by adding sodium phosphate, or, better
still, by the addition of ammonium oxalate in great excess. In both
cases the characteristic coloration from permanganic acid is developed
by the action of the current at the positive pole; this, however,
disappears in the direction of the negative electrode. After the greater
portion of the ammonium oxalate has been converted into carbonate, the
coloration and necessarily the formation of manganese peroxide begins.
Ammonium oxalate is added to the solution, and heat applied; then three
or four grammes more of ammonium oxalate are dissolved in the liquid,
which is then immediately submitted to electrolysis. When the amount of
manganese is small, the separation of the two elements takes place very
rapidly, and the results are accurate. If the amount of manganese is
more than double that of iron, the separation of the latter will take a
much longer time. Then, in order to effect a complete separation of the
two elements, it is necessary to redissolve the deposited manganese in
oxalic acid (the acid is added, without interrupting the current, until
the liquid becomes red), and the current is allowed to continue its
action.
It was found desirable, in effecting this separation, not to employ
too strong a current (two Bunsen elements will suffice), and only
to increase the strength of the current when it is necessary, in
consequence of a large amount of manganese being present, to redissolve
the peroxide.
When the process is completed, it is not advisable to allow the current
to act any longer, for otherwise some of the peroxide may adhere firmly
to the iron, and the latter (after previously having poured off the
liquid) must be redissolved in oxalic acid, that is to say, the
electrolysis must be repeated. As has been already mentioned in the
determination of manganese as peroxide, its precipitation from ammonium
oxalate is not complete. The solution which contains the greater portion
of manganese, suspended as peroxide, must first, therefore, be boiled to
decompose the ammonium carbonate; the remainder of the ammonium oxalate
is neutralized with nitric acid, and the manganese converted into the
sulphide by ammonium sulphide. The manganese sulphide is then ignited in
a current of hydrogen, and weighed as such.
SEPARATION OF IRON AND ALUMINUM.
The quantitative separation of iron from aluminum, which presented many
difficulties according to the older methods, may be easily performed
by electrolysis. If a solution of iron ammonium oxalate and aluminum
oxalate, to which an excess of ammonium oxalate has been added, be
submitted to the action of the electric current, the iron will be
deposited as a firmly adhering coat on the negative electrode, while
the aluminum oxide remains in solution, just so long as the quantity
of ammonium oxalate is in excess of the quantity of ammonium carbonate
produced. When, finally, a precipitation of aluminum oxide takes place
the liquid is almost free from iron. From time to time, the solution, in
which the aluminum oxide is suspended, is tested for iron by ammonium
sulphide, and the current is interrupted when no further reaction is
observed. The best method of procedure is to add ammonium oxalate in
excess to a neutral, a slightly acid solution, or to one which has been
neutralized by the addition of ammonium hydrate (a hydrochloric acid
solution is not well adapted for this purpose); then as much more solid
ammonium oxalate is added until for every 0.1 gramme there is 2 to
3 grammes of the oxalate present. The hot solution is then directly
submitted to the action of the electric current. After the iron has been
precipitated, it is best to stop the action of the current before all
the aluminum oxide is thrown down, for otherwise a portion of the latter
may adhere firmly to the iron, and be difficult to remove.
In such a case, as was mentioned previously in the separation of iron
from manganese, it is necessary to redissolve the iron (after previously
having poured off the liquid) in oxalic acid, and then the electrolysis
is continued.
In order to effect the complete precipitation of the aluminum oxide from
the solution which was poured from the iron, ammonium hydrate is added,
and the solution boiled for some time, and then the aluminum oxide is
determined in the usual manner. When the quantity of aluminum is less
than that of iron, this method may be relied upon to give exact results.
With the reverse (_i. e._, an excess of iron) the precipitate
of aluminum oxide must be dissolved in oxalic acid (without the
interruption of the current), and the electrolysis continued.--_Berichte
der Deutschen Chemischen Gesellschaft_, 14, 1662.
* * * * *
THE CULTIVATION OF PYRETHRUM AND MANUFACTURE OF THE POWDER.
In accordance with an announcement in the March number of the
_Naturalist_, the editor of this department has sent out the seed of two
species of pyrethrum, viz. _P. roseum_ and _P. cinerarioefolium_, to
a large number of correspondents in different parts of North America.
Every mail brings us some inquiries for further particulars and
directions to guide in the cultivation of the plant and preparation of
the powder. We have concluded, therefore, that such information as is
obtainable on these heads will prove of public interest, and we shall
ask Professor Bessey's pardon for trenching somewhat on his domain.
There are very few data at hand concerning the discovery of the
insecticide properties of pyrethrum. The powder has been in use for many
years in Asiatic countries south of the Caucasus mountains. It was sold
at a high price by the inhabitants, who successfully kept its nature a
secret until the beginning of this century, when an Armenian merchant,
Mr. Jumtikoff, learned that the powder was obtained from the dried
and pulverized flower-heads of certain species of pyrethrum growing
abundantly in the mountain region of what is now known as the Russian
province of Transcaucasia. The son of Mr. Jumtikoff began the
manufacture of the article on a large scale in 1828, after which year
the pyrethrum industry steadily grew, until to-day the export of the
dried flower-heads represents an important item in the revenue of those
countries.
Still less seems to be known of the discovery and history of the
Dalmatian species of pyrethrum (_P. cinerarioefolum_), but it is
probable that its history is very similar to that of the Asiatic
species. At the present time the pyrethrum flowers are considered by far
the most valuable product of the soil of Dalmatia.
There is also very little information published regarding either the
mode of growth or the cultivation of pyrethrum plants in their native
home. As to the Caucasian species we have reasons to believe that they
are not cultivated, at least not at the present time, statements to the
contrary notwithstanding.[1]
[Footnote 1: Report Comm. of Patents, 1857, Agriculture, p. 130.]
The well-known Dr. Gustav Radde, director of the Imperial Museum of
Natural History at Tiflis, Transcaucasia, who is the highest living
authority on everything pertaining to the natural history of that
region, wrote us recently as follows: "The only species of its genus
_Pyrethrum roseum_, which gives a good, effective insect powder, is
nowhere cultivated, but grows wild in the basal-alpine zone of our
mountains at an altitude of from 6,000 to 8,000 feet." From this it
appears that this species, at least, is not cultivated in its native
home, and Dr. Radde's statement is corroborated by a communication of
Mr. S. M. Hutton, Vice-Consul General of the U. S. at Moscow, Russia, to
whom we applied for seed of this species. He writes that his agents were
not able to get more than about half a pound of the seed from any one
person. From this statement it may be inferred that the seeds have to be
gathered from the wild and not from the cultivated plants.
As to the Dalmatian plant it is also said to be cultivated in its native
home, but we can get no definite information on this score, owing to the
fact that the inhabitants are very unwilling to give any information
regarding a plant the product of which they wish to monopolize. For
similar reasons we have found great difficulty in obtaining even small
quantities of the seed of _P. cinerarioefolium_ that was not baked or in
other ways tampered with to prevent germination. Indeed, the people
are so jealous of their plant that to send the seed out of the country
becomes a serious matter, in which life is risked. The seed of
_Pyrethrum roseum_ is obtained with less difficulty, at least in small
quantities, and it has even become an article of commerce, several
nurserymen here, as well as in Europe, advertising it in their
catalogues. The species has been successfully grown as a garden plant
for its pale rose or bright pink flower-rays. Mr. Thomas Meehan, of
Germantown, Pa., writes us: "I have had a plant of _Pyrethrum roseum_ in
my herbaceous garden for many years past, and it holds its own without
any care much better than many other things. I should say from this
experience that it was a plant which will very easily accommodate itself
to culture anywhere in the United States." Peter Henderson, of New York,
another well-known and experienced nurseryman, writes: "I have grown the
plant and its varieties for ten years. It is of the easiest cultivation,
either by seeds or divisions. It now ramifies into a great variety of
all shades, from white to deep crimson, double and single, perfectly
hardy here, and I think likely to be nearly everywhere on this
continent." Dr. James C. Neal, of Archer, Fla., has also successfully
grown _P. roseum_ and many varieties thereof, and other correspondents
report similar favorable experience. None of them have found a special
mode of cultivation necessary. In 1856 Mr. C. Willemot made a serious
attempt to introduce and cultivate the plant[1] on a large scale in
France. As his account of the cultivation of pyrethrum is the best
we know of we quote here his experience in full, with but few slight
omissions: "The soil best adapted to its culture should be composed of
pure ground, somewhat silicious and dry. Moisture and the presence of
clay are injurious, the plant being extremely sensitive to an excess of
water, and would in such case immediately perish. A southern exposure is
the most favorable. The best time for putting the seeds in the ground is
from March to April. It can be done even in the month of February if the
weather will permit it. After the soil has been prepared and the seeds
are sown they are covered by a stratum of ground mixed with some
vegetable mould, when the roller is slightly applied to it. Every five
or six days the watering is to be renewed, in order to facilitate the
germination. At the end of about thirty or forty days the young plants
make their appearance, and as soon as they have gained strength enough
they are transplanted at a distance of about six inches from each other.
Three months after this operation they are transplanted again at a
distance of from fourteen to twenty inches, according to their strength.
Each transplantation requires, of course, a new watering, which,
however, should only be moderately applied. The blossoming of the
pyrethrum commences the second year, toward the end of May, and
continues to the end of September." Mr. Willemot also states that the
plant is very little sensitive to cold, and needs no shelter, even
during severe winters.
[Footnote 1: Mr. Willemot calls his plant _Pyrethre du Caucase (P.
Willemoti._ Duchartre), but it is more than probable that this is only
a synonym of _P. roseum_. We have drawn liberally from Mr. Willemot's
paper on the subject, a translation of which may be found in the Report
of the Commissioner of Patents for the year 1861, Agriculture, pp.
223-331.]
The above quoted directions have reference to the climate of France, and
as the cultivation of the plant in many parts of North America is yet
an experiment, a great deal of independent judgment must be used. The
plants should be treated in the same manner as the ordinary Asters of
the garden or other perennial Compositae.
As to the Dalmatian plant, it is well known that Mr. G. N. Milco, a
native of Dalmatia, has of late years successfully cultivated _Pyrethrum
cinerarioefolium_ near Stockton, Cal., and the powder from the
California grown plants, to which Mr. Milco has given the name of
"Buhach," retains all the insecticide qualities and is far superior to
most of the imported powder, as we know from experience. Mr. Milco
gives the following advice about planting--advice which applies more
particularly to the Pacific coast: "Prepare a small bed of fine, loose,
sandy, loamy soil, slightly mixed with fine manure. Mix the seed with
dry sand and sow carefully on top of the bed. Then with a common rake
disturb the surface of the ground half an inch in depth. Sprinkle the
bed every evening until sprouted; too much water will cause injury.
After it is well sprouted, watering twice a week is sufficient. When
about a month old, weed carefully. They should be transplanted to loamy
soil during the rainy season of winter or spring."
Our own experience with _P. roseum_ as well as _P. cinerarioefolium_
in Washington, D. C., has been so far quite satisfactory. Some that we
planted last year in the fall came up quite well in the spring and will
perhaps bloom the present year. The plants from sound seed which we
planted this spring are also doing finely, and as the soil is a rather
stiff clay and the rains have been many and heavy, we conclude that Mr.
Willemot has overstated the delicacy of the plants.
In regard to manufacturing the powder, the flower heads should be
gathered during fine weather when they are about to open, or at the time
when fertilization takes place, as the essential oil that gives the
insecticide qualities reaches, at this time, its greatest development.
When the blossoming has ceased the stalks may be cut within about four
inches from the ground and utilized, being ground and mixed with the
flowers in the proportion of one-third of their weight. Great care must
be taken not to expose the flowers to moisture, or the rays of the sun,
or still less to artificial heat. They should be dried under cover and
hermetically closed up in sacks or other vessels to prevent untimely
pulverization. The finer the flower-heads are pulverized the more
effectually the powder acts and the more economical in its use. Proper
pulverization in large quantities is best done by those who make a
business of it and have special mill facilities. Lehn & Fink, of New
York, have furnished us with the most satisfactory powder. For his own
use the farmer can pulverize smaller quantities by the simple method of
pounding the flowers in a mortar. It is necessary that the mortar be
closed, and a piece of leather through which the pestle moves, such
as is generally used in pulverizing pharmaceutic substances in a
laboratory, will answer. The quantity to be pulverized should not exceed
one pound at a time, thus avoiding too high a degree of heat, which
would be injurious to the quality of the powder. The pulverization being
deemed sufficient, the substance is sifted through a silk sieve, and
then the remainder, with a new addition of flowers, is put in the mortar
and pulverized again.
The best vessels for keeping the powder are fruit jars with patent
covers or any other perfectly tight glass vessel or tin box.--_American
Naturalist_.
* * * * *
THE REMOVAL OF NOXIOUS VAPORS FROM ROASTING FURNACE GASES.
In a paper read before the Aix-la-Chapelle section of the _Verein
deutscher Ingenieure_, Herr Robert Hasenclever presents a summary of
the results obtained with various methods for the absorption of the
sulphurous acid generated during the roasting of zinc-blende and other
sulphurets. Though most of our own metallurgical works are not so
located as to be forced to pay much attention to the removal of noxious
vapors, the efforts made abroad possess some interest for American
metallurgists. Besides containing sulphurous acid, the gases from the
roasting furnaces hold varying quantities of sulphuric acid, and Dr.
Bernoulli describes a process applied on a large scale in Silesian zinc
works, where the gases were passed through towers filled with lime. It
was found that there was no trouble on account of the absorption of
carbonic acid by the lime, and that the latter acted very efficiently
in reducing the quantity of sulphurous acid. Before entering the tower,
they contained 0.258 per cent. by volume of sulphurous acid and 2.45 per
cent. of carbonic acid; while, after their passage through it, they
held 0.017 and 2.478 per cent, respectively. The process, however, is
declared by Herr Hasenclever to be too costly for ordinary working,
although he does not deny its value under special circumstances.
The removal of anhydrous sulphuric acid from the gases from
roasting-furnaces has hitherto, as at the Waldmeister works, near
Stolberg, been effected by means of water trickling down in a tower
filled with coke, the gases entering below and moving upward. Herr
Hasenclever tested the Freytag method, in which the water is replaced
by sulphuric acid, and obtained favorable results, as shown by the
following analyses of the gases before and after treatment. The figures
given are grammes per 1,000 liters:
BEFORE. AFTER.
SO_2. SO_3. SO_2. SO_3.
8.24 0.63 5.74 0.00
8.29 0.37 6.74 0.07
9.36 0.69 6.96 0.00
9.46 0.63 7.38 0.05
10.03 1.08 7.69 0.09
16.52 2.97 14.39 0.23
17.90 1.97 13.32 0.11
17.80 2.46 16.18 0.69
The average absorption for the first set of four analyses when three
roasting-furnaces were discharging into the tower was 95 per cent. of
the sulphuric acid, and that of the second set of four or five furnaces
was 90 per cent. The amount of sulphuric acid charged per twenty-four
hours was about 5,000 kilogrammes of 50 degrees Baume, which flowed off
with a density of from 56 to 58 degrees Baume. The quantity of acid
condensed varied according to the nature of the ores and the number of
furnaces working. It ranged between 300 and 1,000 kilogrammes of 60
degrees Baume per twenty-four hours. The condensation of anhydrous
sulphuric acid would pay, according to estimates submitted by Herr
Hasenclever; but to pass the gases through a tower filled with lime,
in order to get rid of the remaining sulphurous acid, would prove too
expensive at Stolberg. An attempt to use milk of lime proved partially
successful; but it was not followed up, because it was decided to
experiment with the process suggested by Prof. Cl. Winkler, of Freiberg,
who proposes to pass the gases through a tower filled with iron in
some suitable shape, over which water trickles. From the solution thus
obtained, sulphurous acid pure enough to be used for the manufacture
of sulphuric acid, sulphur, and a solution of green vitriol is made.
Experiments with this process are making at Freiberg and at the Rhenania
Works, near Stolberg. The trouble with the majority of methods thus
far is, that the draught of the furnaces is so much impeded by the
absorption towers that fans, blowers, or steam jets must be used to
carry the gases through it.
The experience of Herr Hasenclever has proved how difficult it is to
find a satisfactory means of removing the noxious vapors from furnace
gases without incurring too serious an expense. Thus far the value of
the products obtained by absorption of sulphurous acid has not been
equal to the cost of producing them. Herr C. Landsberg, who is general
manager of the Stolberg Company, has had similar experience, though his
experiments were made to test methods suggested at various times by Dr.
E. Jacob and Dr. Aarland. Both are very ingenious, and were successful
on a small scale, but failed when tried in actual working.--_Engineering
and Mining Journal_.
* * * * *
NEW GAS EXHAUSTER.
In common practice, the new exhauster at the Old Kent Road passes
about five million cubic feet of gas per day of twenty-four hours, and
requires the attention of two men and two boys for driving and stoking,
at the following cost:
s. d.
Wages--2 men, at 5s. 6d 11 0
Wages--2 boys, at 3s. 6d 7 0
-----
L 0 18 0
Oil, 1 gallon 0 3 6
Waste, 5 lb 0 1 0
--------
Total L 1 2 6
for five million cubic feet, or 0.054d. per 1,000 feet. The boiler
burns a mixture of coke and breeze, chiefly the latter, of small value,
costing 0.0174d. per 1,000 feet of gas exhausted; therefore the total
cost of exhausting gas by the new system is--
Fuel 0.0174d
Wages, oil, and waste 0.0540
--------
Total 0.07l4d.
per 1,000 cubic feet of gas, exclusive of repairs, which will be
decidedly less for the new exhauster than for that on the older system,
from the friction being so much less. The feed water evaporated is at
the rate of about 7.4 lb. per pound of breeze, and 7.5 lb. per pound of
coke.
[Illustration: IMPROVED GAS EXHAUSTER.]
It will be seen that the exhausting arrangements at the Old Kent Road
are extremely economical, the cost of fuel being reduced to a minimum;
while a man and boy by day, and their reliefs for the night, attend to
the machinery inside the exhauster-house, and also to the pumps outside,
and stoke the boiler as well.--_Journal of Gas Lighting_.
* * * * *
ADVANCE IN THE PRICE OF GLYCERINE
The continued advance in the price of glycerine continues to excite
comment among those who deal in or use it, and no one seems to know
exactly where or when the advance is likely to stop, or by what means a
retrograde movement will probably be brought about.
As we have heretofore stated, the rise has been brought about by a
combination of two causes--a falling off in production and a great
increase in the demand, owing to the discovery of new uses for it, and
the extension of the branches of manufactures in which it has been
heretofore employed.
In pharmacy, it is coming more and more into use daily, and in various
other branches of manufacture the same tendency is observable. It
has proved itself so elegant and so convenient a vehicle for the
administration of various medicinal substances, is so easily miscible
with both water and alcohol, and is so pleasant to the taste, that it
seems almost a wonder that it should have been so long in attaining the
rank among the articles of the _Materia Medica_ which it now occupies.
The two manufactures, however, which seem to lead in the demand for
glycerine are of nitro-glycerine and of oleomargarine.
The uses to which it is put for the former are well known, but precisely
what the latter could want of the article is not, at first glance,
quite so obvious. We are informed, however, that it is valued for its
antiseptic properties, and also for its softening effect on the _quasi_
butter. Be this as it may, it seems that both here and in Europe the
makers of these two articles are buying largely of both crude and
refined glycerine.
So it appears that the willingness of the people to eat artificial
butter, and the progress in schemes for internal improvement, such as
the De Lesseps Canal, for instance, to say nothing of the European
revolutionists, are responsible to a great extent for the scarcity of an
important article of pharmaceutical use.
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