scene of such intestinal commotions and bitter strife through the
whole period of her existence, from the Spanish conquest up to within
a few years, is at present happily in a state of comparative peace
and quiet; the laws are less disregarded, brigandage is gradually
disappearing, more attention is being paid to the protection of life
and property, and public education is in a prosperous condition. No
greater evidence of this felicitous state of affairs could be afforded
than that shown in the display of energy and zeal with which the
present administration, aided by the foremost Mexican scientists,
is carrying out an extended system of scientific explorations,
investigations, and internal improvements; and the progress of which
is being recorded in a valuable series of government publications;
one of these--the _Annals of the Minister of Public Works_--being
now before us. This volume, the third of the series, begins with
an article by the able director of the National Meteorological
Observatory, Sr. Mariano Barcena, calling attention, in the first
place, to the great national importance, as well as necessity, of a
well organized system of meteorological observations; (2) giving a
description of the Mexican Observatory, its equipment, the questions
it proposes to investigate, and the hours of observation; (3)
an explanation, accompanied by charts, of the daily system of
registration pursued at the observatory; and, finally, observations on
the periodic phenomena of vegetation, and notes on the orography
and geology of the valley of Mexico. Sr. A. Anquiano follows with a
communication on the "Geographical Position of Chalco," prefacing
the results of his labors by an able essay on the "Mexican Method"
of determining the latitude of places, a "method" founded on an
observation of the stars. It would be interesting to quote from this,
but our limited space will not permit. The "Citlaltepetl Commission,"
consisting of the engineers, Srs. Plowes, Rodriguez, and Vigil, whose
patriotic ardor induced the minister to commission them to explore
"and be the first to plant the flag of Mexican science on the snow
clad peak of Citlaltepetl," render their report of operations during
the year 1877 in the form of an exceedingly interesting memoir. They
ascertained the peak of the volcano Citlaltepetl (or Orizaba) to be
17,651 feet above the level of the sea, which is 292 feet more
than Humboldt made it. After a somewhat exhaustive treatise on the
"Telescope and its Amplifying Power," by Sr. Jimenez, we have a long
and extremely interesting account of the Ancient Aqueduct of Zempoala,
one of the most notable of existing monuments of the old Spanish rule.
These aqueducts (for there were three) were projected and carried to a
successful termination by an humble and ignorant Franciscan monk--the
Friar Tembleque. The construction of these remarkable works, begun
in 1554 and occupying a period of 17 years, was undertaken for the
purpose of carrying water from Zempoala to Otumba (a distance of
27 miles), and was the occasion of a curious contract between the
inhabitants of these two cities. It seems that Otumba, situated at a
high elevation, needed water; Zempoala was blessed with water, but was
sadly in need of spiritual advisers; the people of the former city,
therefore, agreed to furnish a certain proportion of friars to
minister to the religious wants of the parties of the second part, and
the latter in return bound themselves to furnish water, and the labor
and materials for the building of an aqueduct to lead it, to the
parties of the first part. No tradition remains to state when these
structures ceased to be used. The longest of the three extends across
the valley of the Papelote, a distance of 2,960 feet, and consists
of 68 arches, the highest of which has an altitude of 106 feet. Senor
Salazar urges on the Minister of Public Works the importance of having
these monuments of a past age repaired and restored, not alone for
archaeological reasons, but because Otumba to-day is as greatly in
need of running water as it was in that remote period when these
viaducts were constructed. Senor Barcena follows with a description
and colored plate of a plant (_Gaudichaudia Enrico-Martinezii_) new
to the Mexican flora, and Sr. Federico Weidner with some "General
Reflections on the Iron Industry of the Country." Succeeding the
latter paper, an exhaustive article by the same writer gives us,
from a geological point of view, the structure, as far as can be
ascertained, of the "Cerro de Mercado" of Durango, which is said to be
one vast mass of iron. The author after a thorough examination of this
hill, last year, concludes that it is of eruptive or volcanic origin.
This is contrary to the statements made in most published works,
the authors of which probably derived their notions from the views
expressed by Humboldt, who was of the opinion that this mass of iron
was an immense aerolite. Sr. Weidner, however, concludes that the
great traveler never visited the locality in person, but obtained his
information from heresay. He shows that the hill is deficient in the
chemical constituents of aerolites, namely, iron, nickel, and cobalt,
in a native or malleable state; but, on the contrary, is made up in a
great measure of crystalline magnetic iron, and various useful oxides
of the same metal. By a careful estimate of the quantity of iron
contained in that portion only of the Cerro which appears above the
surface of the soil, the author obtains as a result the enormous sum
of 507,000,000 pounds, and this reduced to a metallic state would
yield 250,000,000 pounds of pure iron. The structure of this
remarkable hill is made apparent to the reader by means of an
excellent geological section, in colors, accompanying the text.
The volume closes with some notes by Sr. Barcena on the "Hydrographic
System of the Hacienda of Cienega de Mata, and its application to one
of the theories that explain Natural Fountains."
In taking leave of this subject we have to congratulate the Mexican
Government not only for the valuable matter contained in its
scientific publications, but also for the very excellent style in
which the latter are being issued. The general make up of the volume
before us leaves little to be desired; the arrangement of the types
is extremely tasty, the imprint is clean, sharp, and clear, the
paper good, the margins of the pages broad, and the illustrations
exceedingly well executed. It is to be sincerely hoped that the
present state of peace, which our sister republic is enjoying, will
endure for numerous years to come; and that the scientific work begun
under such happy auspices may go on uninterruptedly until the whole
country shall have been thoroughly explored. For as yet, we know but
comparatively little about the geology of Mexico, and a great deal is
yet to be learned, too, about her natural productions.
* * * * *
CORRESPONDENCE.
* * * * *
ALUM IN BREAD.--A REPLY TO DR. MOTT'S ARTICLE IN SCIENTIFIC AMERICAN
OF NOVEMBER 16, ENTITLED "DELETERIOUS USE OF ALUM IN BAKING POWDER."
By W. P. CLOTWORTHY, BALTIMORE, MD.
On August 13, 1878, I obtained letters patent for the exclusive right
to use exsiccated ammonia alum in baking powders. This fact I state
that the public may know the reason that elicits this reply to
the remarkable article on adulterations in baking powders, in the
SCIENTIFIC AMERICAN of Nov. 16th, emanating from the pen of Henry A.
Mott, Jr. I wish the Professor had been equally candid in stating his
reasons for contributing the article. It is rare for a chemist to turn
philanthropist without some consideration. The analysis of forty-two
baking powders requires no little labor; twenty-one were examined
at the expense of the government for the benefit of the Indian
Department, the others, no doubt, at the expense and for the benefit
of the Royal Baking Powder Company. I hope his services have been
liberally requited. The public certainly owe him nothing for his labor
or opinions. An excuse can be made for the prejudice existing against
the use of alum in any form for baking purposes; it is an inheritance
from a preceding age; but no apology can be offered for a practical
chemist in this day, who labors to keep alive and foster a prejudice
by the suppression of truths and facts. Professor Mott, in attempting
to prove a fraud in food, has perpetrated a fraud in facts. That this
opinion may not be unwarranted, I will state the facts about alum,
which may be new to the public, but familiar to every chemist. Alum
was formerly a compound of sulph. alumina and sulph. potash. In the
past ten years nearly all manufacturers of alum have substituted
sulph. ammonia for the sulph. potash; this change removes from alum
a dangerous and objectionable ingredient, and adds a healthful
one. Professor Mott recommends the use of ammonia in the form of a
carbonate--carbonate of ammonia is one of the results in baking powder
of the decomposition which takes place between alum and bicarbonate of
soda; in the complete decomposition which takes place pure alumina is
eliminated, highly recommended as an antacid. During the process
of baking, alum is completely decomposed through the liberation of
carbonic acid. Professor Mott must have known this, yet with this
knowledge warns the public on the deleterious effect of alum in bread.
About the first of last October I determined to vindicate the use
of exsiccated ammonia alum as a substitute for cream of tartar, and
accordingly issued a circular to the trade; from this circular I now
give the following extract, which enters minutely into the subject:
"To claim that an experience of 35 years in compounding medicines
should entitle my opinion on chemicals and chemical compounds to a
respectful consideration, is neither presumptuous nor unreasonable.
With this simple introduction I now avow myself the originator
and patentee of exsiccated ammonia alum baking powder. The use of
exsiccated ammonia alum has been declared unhealthful by the advocates
of other baking powders, and every manufacturer using it has been held
up for public reprobation. This has been done by rival manufacturers,
either through ignorance or malice; if from the former they are to be
pitied, if from the latter they are contemptible. These opinions have
been promulgated by kitchen chemists, whose circle of knowledge begins
and ends with cream tartar and soda; and even of these articles they
only know that cream tartar is in some way derived from grapes. In
this circular I propose to state a few facts in relation to cream
tartar and exsiccated alum, and the combinations they form with
bicarbonate of soda, and allow you to form your own opinion of their
respective merits. Crude tartar is the incrustation found in wine
casks. It contains coloring matter and about 15 per cent of lime.
This article is purified and called the cream of tartar, but it is
impossible to extract all the lime. Commercially pure cream tartar
contains at least 5 per cent of lime. When cream tartar is used in
proportion of two parts to one of bicarbonate of soda, you will have
an average of 3 to 4 per cent of lime. In using cream tartar and soda
in baking, a chemical change commences as soon as water is added; the
cream tartar unites with the soda, setting free the carbonic acid gas,
which lightens the bread, and the residue is Rochelle salts. This
is what you eat in your bread, the cream tartar and soda entirely
disappearing in the process of baking, by forming this salt. Any
doctor or chemist will confirm the above statement. When I undertook
to manufacture baking powder, I labored to improve the quality and
cheapen the cost. The first I accomplished by retaining the carbonic
acid until heat was applied, the latter, by manufacturing a more
economical acid than foreign cream tartar. After more than a
thousand experiments covering a period of six months, I discovered by
exsiccating ammonia alum I provided an article that would possess the
necessary qualities. This article no more resembles the ordinary
alum than charcoal resembles wood--it is light, porous, friable, and
without taste. This article, under the influence of heat, combines
with the soda and forms Glauber salts. In baking, the alum unites
with the soda, just as cream tartar unites. In using the baking powder
prepared according to my formula, you have in your bread Glauber
instead of Rochelle salts. To your physician apply for his opinion
of these salts; I will bow to his decision. Another false impression
these zealous guardians of the public health have made is, that I
used the exsiccated alum because it was cheap. The fact is that when I
commenced its use it cost by the thousand pounds 12 per cent. more
than the best cream tartar is worth to-day, and 33 per cent. more than
average price of that article for the past year. I have since reduced
the cost of manufacturing, and as I did so, correspondingly reduced
the price of powder to the public. I regard the quantity of soda in
cream tartar baking powders as very objectionable; they generally
contain about 33 per cent. In my powder only 20 per cent. The
prejudice in the public mind against alum, originated in the habit of
the English bakers buying damaged flour, and by the addition of crude
alum, made their bread in appearance equal to that made from best
flour. Against this practice laws were enacted, not so much against
the qualities of alum, as against its use in covering up a fraud
in flour. This was the common potash alum and uncombined with any
carbonated alkali, and it passed into the stomach unchanged. It is
a trick--for it deserves no better name--of our rivals to show by
chemical analysis that my powder contains alum, but are careful
neither to state the kind nor the change it undergoes in baking. The
manufacturer who knowingly misrepresents the goods of a rival, may
well be doubted when he speaks of the quality of his own.
"Great stress is laid on the fact that cream tartar is a vegetable
acid, the product of the grape, hence it must be healthy. They forget
that cream tartar is not entirely vegetable, but principally second
handed minerals. It is a compound of tartaric acid, potash, and lime;
the last two are minerals, which the grape takes up from the earth,
but redeposits them as crude tartar when fermentation converts the
grape into wine. In 1807 Sir Humphry Davy from this crude tartar first
made the metal potassium. Of lime it is unnecessary to speak. The
potash and lime form the bulk of cream tartar. In ammonia alum there
is no more mineral substance than in cream tartar. The chemistry
of nature is wonderful. Vegetation lives on minerals--wheat, corn,
potatoes, are all mineral compounds. Lime, soda, potash, magnesia,
sulphur, iron, etc., are all found abundantly in water and grain, and
all these minerals are essential in food."
Professor Mott has given the Royal Baking Powder the benefit of his
indorsement; it may be all that he claims for it. But baking powders
are now judged by constituent ingredients and chemical analysis; to
this test I propose to bring the Royal. It is now in the hands of a
competent chemist, and when the analysis is complete I will give
the public the benefit of a comparison between that powder and the
Patapsco. I will take Professor Mott's analysis of Patapsco, which,
though not correct, I accept as such. The comparison will be made on
the healthfulness of constituents in combination, and the chemical
changes they undergo in baking. This is a progressive age. The people
want facts, and they will form their own theories. Will the reader
believe that in the reign of Henry VIII. of England, a citizen
of London was executed for burning coal, which was then a capital
offense? A pope about the same time issued a Bull excommunicating all
Catholics who used tobacco, calling it the devil's weed. To-day coals
still burn, and tobacco solaces millions of the civilized world. If
the Royal Baking Powder Company (what a misnomer) possessed royal
prerogatives, the advocates of exsiccated alum would fare no better
than they did under the sumptuary laws of England. Professor Mott has
fulminated _ex cathedra_ his blast, but we survive. "Truth is a torch,
the more 'tis shook it shines." Our strength is in the intelligence of
the age. SMITH, HANWAY & Co., Baltimore.
* * * * *
THE ELONGATION OF TREE TRUNKS.
The _College Quarterly_ says that experiments made at the Iowa
Agricultural College show that the popular notion that the trunks
of trees elongate is entirely erroneous. Tacks were driven into the
trunks of various trees, and the distance between them accurately
measured. At the end of the season they were found to have neither
increased nor decreased their distances. In the experiment, tree
trunks were selected of all ages, from one year up to five or six, and
in no case was there any change whatever noticeable.
* * * * *
ASTRONOMICAL NOTES.
BY BERLIN H. WRIGHT.
PENN YAN, N. Y., Saturday, December 14, 1878. The following
calculations are adapted to the latitude of New York city, and are
expressed in true or clock time, being for the date given in the
caption when not otherwise stated:
PLANETS.
H.M.
Mars rises 4 57 mo.
Jupiter sets 7 54 eve.
Saturn in meridian 6 16 eve.
Uranus rises 10 11 eve.
Neptune in meridian 8 48 eve.
FIRST MAGNITUDE STARS, ETC.
H.M.
Alpheratz in meridian 6 28 mo.
Mira (var.) in meridian 8 39 eve.
Algol (var.) in meridian 9 26 eve.
7 stars (Pleiades) in merid. 10 06 eve.
Aldebaran in meridian 10 54 eve.
Capella in meridian 11 33 eve.
Rigel in meridian 11 34 eve.
Betelgeuse in meridian 0 18 mo.
Sirius rises 8 05 eve.
Procyon rises 7 40 eve.
Regulus rises 9 43 eve.
Spica rises 2 24 mo.
Arcturus rises 1 27 mo.
Antares rises 6 30 mo.
Vega sets 9 52 eve.
Altair sets 8 40 eve.
Deneb sets 1 02 mo.
Fomalhaut sets 9 16 eve.
MOON'S PLACE IN THE CONSTELLATIONS AT 7 P.M.
Saturday, Cancer 26 deg.
Sunday, Leo 9 deg.
Monday, Leo 23 deg.
Tuesday, Virgo 7 deg.
Wednesday, Virgo 22 deg.
Thursday, Libra 6 deg.
Friday, Libra 21 deg.
REMARKS.
The sun will attain his greatest southern declination and enter the
constellation _Sagittarius_ December 21, 5h. 45m. evening, at which
time winter begins. Mars will be 5 deg. north of the moon December 21, in
the morning. Saturn will be 90 deg. east of the sun December 18, passing
the meridian at 6 o'clock in the evening. He is now advancing among
the stars, and will soon be again upon the equinoctial colure. Uranus
will be nearly 4 deg. north of the moon December 15.
* * * * *
SYMPATHETIC INKS.
Under the name of sympathetic inks are designated certain liquids
which, being used for writing, leave no visible traces on the paper,
but which, through the agency of heat, or by the action of chemicals,
are made to appear in various colors. The use of such means for secret
correspondence is very ancient. Ovid, Pliny, and other Roman writers
speak of an ink of this kind, which, however, was nothing more than
fresh milk. It merely sufficed to dust powdered charcoal over the
surface of the paper upon which characters had been traced with the
colorless fluid, when the black powder adhered only to those places
where the fatty matter of the milk had spread. Such a process,
however, was merely mechanical, and the results very crude.
A great number of sympathetic inks may be obtained by means of
reactions known to chemistry. For instance, write on paper with a
colorless solution of sugar of lead; if the water that is used for the
solution be pure, no trace of the writing will remain when it becomes
dry. Now hold the paper over a jet of sulphureted hydrogen, and the
characters will immediately appear on the paper, of an intense black
color. The following recipes for inks of this kind are more simple:
If writing be executed with a dilute solution of sulphate of iron, the
invisible characters will appear of a beautiful blue, if the dry paper
be brushed over with a pencil full of a solution of yellow prussiate
of potash; or they will be black, if a solution of tannin be
substituted for the prussiate. If the characters be written with
a solution of sulphate of copper, they will at once turn blue on
exposing to the vapors of ammonia. Another sympathetic ink is afforded
by chloride of gold, which becomes of a reddish purple when acted upon
by a salt of tin. A red sympathetic ink may be made in the following
manner: Write with a very dilute solution of perchloride of iron--so
dilute, indeed, that the writing will be invisible when dry. By
holding the paper in the vapor arising from a long-necked glass
flask containing sulphuric acid and a few drops of a solution of
sulpho-cyanide of potassium, the characters will appear of a blood-red
color, which will again disappear on submitting them to the vapors of
caustic ammonia. This experiment can be repeated _ad infinitum_.
During the war in India, some years ago, important correspondence
was carried on by the English by means of the use of rice water as a
writing fluid. On the application of iodine the dispatches immediately
appeared in blue characters.
Sympathetic inks which are developed under the influence of heat only
are much easier to use than the foregoing. The liquids which possess
such a property are very numerous. Almost every one perhaps knows that
if writing be executed on paper with a clean quill pen dipped in onion
or turnip juice, it becomes absolutely invisible when dry; and that
when the paper is heated the writing at once makes its appearance
in characters of a brown color. All albuminoid, mucilaginous, and
saccharine vegetable juices make excellent sympathetic inks; we may
cite, as among the best, the juices of lemon, orange, apple, and pear.
A dilute solution of chloride of copper used for writing is invisible
until the paper is heated, when the letters are seen of a beautiful
yellow, disappearing again when the heat that developed them is
removed. The salts of cobalt, as the acetate, nitrate, sulphate, and
chloride, possess a like property. When a dilute solution of these
salts is used as an ink, the writing, although invisible when dry,
becomes blue when exposed to heat. The addition of chloride of iron,
or of a salt of nickel, renders them green, and this opens the way for
a very pretty experiment: If a winter landscape be drawn in India ink,
and the sky be painted with a wash of cobalt alone, and the branches
of the trees be clothed with leaves executed with a mixture of cobalt
and nickel, and the snow-clad earth be washed over with the same
mixture, a magic transformation at once takes place on the application
of heat, the winter landscape changing to a summer scene.
There is a well known proprietary article sold in Paris under the
name of _"Encre pour les Dames"_ (ink for ladies). Hager, in a recent
scientific journal, states that this consists of an aqueous solution
of iodide of starch, and is "specially intended for love letters." In
four weeks characters written with it disappear, preventing all abuse
of letters, and doing away with all documentary evidence of any kind
in the hands of the recipient. The signers of bills of exchange who
use this ink are of course freed from all obligations in the same
length of time.
* * * * *
NEW WIRE CLOTHING FOR BURRING CYLINDERS.
Heretofore two kinds of clothing for cylinders for treating fibrous
material have been employed, one consisting of a set of serrated rings
cut from sheet steel and secured to the periphery of the cylinder, and
the other consisting of flat serrated iron wire. The serrated rings,
of necessity, entail a great loss of material in their manufacture,
and the iron wire clothing is so soft that it soon wears out or
becomes dull, necessitating the reclothing or sharpening of the
cylinder.
[Illustration: NEW WIRE CLOTHING FOR BURRING CYLINDERS.]
Our engraving represents a new form of steel wire clothing for such
cylinders, which was recently patented by Mr. Frank P. Pendleton, of
Philadelphia, Pa.
The improvement consists in notching or nicking the base of the teeth
or back of the wire, so as to admit of bending the wire around the
cylinders without breaking.
* * * * *
PETROLEUM AND GOLD.