Scientific American Supplement, No. 446, July 19, 1884 online

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the food itself in the form of a compound of tin; present, that is to
say, on account of the action of the fluids or juices of the food on the
tin of the can. Such action and such consequent solution of the tin, and
consequent admixture of a possibly assimilable compound of tin with the
food, in my opinion never occurs to an extent which in relation to
health has any significance whatever. The occurrence of tin, not as a
compound, but as the metal itself, is, if possible, still less

During the last fifteen years I have frequently examined canned foods,
not only with respect to the food itself as food, and to the process of
canning, but with regard to the relation of the food to, or the
influence if any of the metal of, the can itself. So lately as within
the past two or three months I have examined sixteen varieties of canned
food for metals, with the following results:

Decimal parts of
a grain of tin
(or other foreign
metal) present in
Name of article a quarter of a lb.

Salmon none.
Lobsters none.
Oysters 0.004
Sardines none.
Lobster paste none.
Salmon paste none.
Bloater paste 0.002
Potted beef none.
Potted tongue none.
Potted "Strasbourg" none.
Potted ham 0.002
Luncheon tongue 0.003
Apricots 0.007
Pears 0.003
Tomatoes 0.007
Peaches 0.004

These proportions of metal are, I say, undeserving of serious notice. I
question whether they represent more than the amounts of tin we
periodically wear off tin saucepans in preparing food - a month ago I
found a trace of tin in water which had been boiled in a tin kettle - or
the silver we wear off our forks and spoons. There can be little doubt
that we annually pass through our systems a sensible amount of such
metals, metallic compounds, and other substances that do not come under
the denomination of food; but there is no evidence that they ever did or
are ever likely to do harm or occasion us the slightest inconvenience.
Harm is far more likely to come to us from noxious gases in the air we
breathe than from foreign substances in the food we eat.

But whence come the much less minute amounts of tin - still harmless, be
it remembered - which have been stated to be occasionally present in
canned foods? They come from the minute particles of metal chipped off
from the tin sheets in the operations of cutting, bending, or hammering
the parts of the can, or possibly melted off in the operations necessary
for the soldering together of the joints of the can. Some may, perhaps,
be cut, off by the knife in opening a can. At all events I not
unfrequently find such minute particles of metal on carefully washing
the external surfaces of a mass of meat just removed from a can, or on
otherwise properly treating canned food with the object of detecting
such particles. The published processes for the detection of tin in
canned food will not reveal more than the amounts stated in the table,
or about those amounts; that is to say, a few thousandths or perhaps two
or three hundredths of a grain, if this precaution be adopted. If such
care be not observed, the less minute amounts may be found. I did not
detect any metallic particles in the twelve samples of canned food just
mentioned, but during the past few years I have occasionally found small
pieces of metal, perhaps amounting in some of the cases to a few tenths
of a grain per pound. Now and then small shot-like pieces of tin, or
possibly solder, may be met with; but no one has ever found, to my
knowledge, such a quantity of actual metallic tin, tinned iron, or
solder as, from the point of view of health, can have any significance

The largest amount of tin I ever detected in actual solution in food was
in some canned soup, containing a good deal of lemon juice. It amounted
to only three-hundredths of a grain in a half pint of the soup as sent
to table. Now, Christison says that quantities of 18 to 44 grains of the
very soluble chloride of tin were required to kill dogs in from one to
four days. Orfila says that several persons on one occasion dressed
their dinner with chloride of tin, mistaking it for salt. One person
would thus take not less than 20 to 30 grains of this soluble compound
of tin. Yet only a little gastric and bowel disturbance followed, and
from this all recovered in a few days. Pereira says that the dose of
chloride of tin as an antispasmodic and stimulant is from 1/16 to ½ a
grain repeated two or three times daily. Probably no article of canned
food, not even the most acid fruit, if in a condition in which it can be
eaten, has ever contained, in an ordinary table portion, as much of a
soluble salt of tin as would amount to a harmless or useful medicinal

Metallic particles of tin are without any effect on man. A thousand
times the quantity ever found in a can of tinned food would do no harm.

Food as acid as say ordinary pickles would dissolve tin. Some
manufacturers once proposed using tin stoppers to their bottles of
pickles. But the tin was slowly dissolved by the acid of the vinegar.
These pickles, however, had a distinctly nasty "metallic" flavor. The
idea was abandoned. Probably any article of food containing enough tin
to disagree with the system would be too nasty to eat. Purchasers of
food may rest assured that the action taken by this firm would be that
usually followed. It is not to the interest of manufacturers or other
venders to offend the senses of purchasers, still less to do them actual
harm, even if no higher motive comes into force.

In the early days of canning, it is just possible that the use of
"spirits of salt" in soldering may have resulted in the presence of a
little stannous, plumbous, or other chloride in canned food; but such a
fault would soon be detected and corrected, and as a matter of fact,
resin-soldering is to my knowledge more generally employed - indeed, for
anything I know to the contrary, is exclusively employed - in canning
food. Any resin that trained access would be perfectly harmless. It is
just possible, also, that formerly the tin itself may have contained
lead, but I have not found any lead in the sheet tin used for canning of
late years.

In conclusion: 1. I have never been able to satisfy myself that a can of
ordinary tinned food contains even a useful medicinal dose of such a
true soluble _compound_ of tin as is likely to have any effect on man.
2. As for the metal itself, that is the filings or actual metallic
particles or fragments, one ounce is a common dose as a vermifuge;
harmless even in that quantity to man, and not always so harmful as
could be desired to the parasites for whose disestablishment it is
administered. One ounce might be contained in about four hundredweight
of canned food. 3. If a possibly harmful quantity of a soluble compound,
of tin be placed in a portion of canned food, the latter will be so
nasty and so unlike any ordinary nasty flavor, so "metallic," in fact,
that no sane person will eat it. 4. Respecting the globules of solder
(lead and tin) that are occasionally met with in canned food, I believe
most persons detect them in the mouth and remove them, as they would
shots in game. But if swallowed, they do no harm. Pereira says that
metallic lead is probably inert, and that nearly a quarter of a pound
has been administered to a dog without any obvious effects. He goes on
to say that as it becomes oxidized it occasionally acquires activity,
quoting Paulini's statement that colic was produced in a patient who had
swallowed a leaden bullet. To allay alarm in the minds of those who fear
they might swallow pellets of solder, I may add that Pereira cites
Proust for the assurance that an alloy of tin and lead is less easily
oxidized than pure lead. 5. Unsoundness in meat does not appear to
promote the corrosion or solution of tin. I have kept salmon in cans
till it was putrid, testing it occasionally for tin. No trace of tin was
detected. Nevertheless, food should not be allowed to remain for a few
days, or even hours, in saucepans, metal baking pans, or opened tins or
cans, otherwise it _may_ taste metallic. 6. Unsound food, canned or
uncanned, may, of course, injure health, and where canned food really
has done harm, the harm has in all probability been due to the food and
not to the can. 7. What has been termed idiosyncrasy must also be borne
in mind. I know a man to whom oatmeal is a poison. Some people cannot
eat lobsters, either fresh or tinned. Serious results have followed the
eating of not only oatmeal or shell fish, but salmon and mutton;
_hydrate_ (misreported _nitrate_) of tin being gratuitously suggested as
being contained in the salmon in one case. Possibly there were cases of
idiosyncrasy in the eater, possibly the food was unsound, possibly other
causes altogether led to the results, but certainly, to my mind, the tin
had nothing whatever to do with the matter.

In my opinion, given after well weighing all evidence hitherto
forthcoming, the public have not the faintest cause for alarm respecting
the occurrence of tin, lead, or any other metal in canned foods. - _Phar.
Jour, and Trans., March 8, 1884, p. 719_.

[In reference to Prof. Attfield's statement contained in the closing
paragraph, we remark: It is well known that mercury is an ingredient of
the solder used in some canning concerns, as it makes an easier melting
and flowing solder. In THE SCIENTIFIC AMERICAN for May 27, 1876, in a
report of the proceedings of the New York Academy of Science, will be
seen the statement of Prof. Falke, who found metallic mercury in a can
of preserved corn beef, together with a considerable quantity of
albuminate of mercury. - EDS. S.A.]

* * * * *


The house shown in the illustration was lately erected from the designs
of Mr. Charles Bell, F.R.I.B.A. Although sufficiently commodious, the
cost has been only about 1,050_l_. - _The Architect_.


* * * * *

Valerianate of cerium in the vomiting of pregnancy is recommended by Dr.
Blondeau in a communication to the _Societe de Therapeutique_. He gives
it in doses of 10 centigrammes three times a day. - _Medical Record_.

* * * * *

RENAISSANCE. - _From The Workshop._]

* * * * *


If there is one point more than another in which the exuberant youth and
vitality of the American nation is visible it is in that of education,
the provision for which is on a most generous scale, carried out with a
determination at which the older countries of the Eastern Hemisphere
have only arrived by slow degrees and painful experience. Of course the
Americans, being young, and having come to the fore, so to speak,
full-fledged, have been able to profit by the lessons which they have
derived from their neighbors - though it is none the less to their credit
that they have profited so well and so quickly. Technical and industrial
education has received a more general recognition, and been developed
more rapidly, than the general education of the country, partly for the
reason that there is no uniform system of the latter throughout the
States, but that each individual State and Territory does that which is
right in its own eyes. The principal reason, however, is that to possess
the knowledge, how to work is the first creed of the American, who
considers that the right to obtain that knowledge is the birthright of
every citizen, and especially when the manual labor has to be
supplemented by a vigorous use of brains. The Americans as a rule do not
like heavy or coarse manual labor, thinking it beneath them; and,
indeed, when they can get Irish and Chinese to do it for them, perhaps
they are not far wrong. But the idea of idleness and loafing is very far
from the spirit of the country, and this is why we see the necessity for
industrial education so vigorously recognized, both as a national duty,
and by private individuals or communities of individuals.

From whatever source it is provided, technical education in the United
States comes mainly within the scope of two classes of institutions,
viz., agricultural and mechanical colleges; although the two are, as
often as not, combined under one establishment, and particularly it
forms the subject of a national grant. Indeed, it may be said that the
scope of industrial education embraces three classes: the farmer, the
mechanic, and the housekeeper; and in the far West we find that
provision is made for the education of these three classes in the same
schools, it being an accepted idea in the newer States that man and
woman (the housekeeper) are coworkers, and are, therefore, entitled to
equal and similar educational privileges. On the other hand, in the more
conservative East and South, we find that the sexes are educated
distinct from each other. In the East, there is generally, also, a
separation of subjects. In Massachusetts, for instance, the colleges of
agriculture and mechanics are separate affairs, the students being
taught in different institutions, viz., the agricultural college and the
institute of technology. In Missouri the separation is less defined, the
School of Mines and Metallurgy being the, only part that is distinct
from the other departments of the University.

One of the chief reasons for the necessity for hastening the extension
of technical education in America was the almost entire disappearance of
the apprenticeship system, which, in itself, is mainly due to the
subdivision of labor so prevalent in the manufacture of everything, from
pins to locomotives. The increased use of machinery, the character of
which is such as often to put an end to small enterprises, has promoted
this subdivision by accumulating workmen in large groups. The beginner,
confining himself to one department, is soon able to earn wages, and so
he usually continues as he begins. Mr. C.B. Stetson has written on this
subject with great force and earnestness, and it will not be amiss to
quote a sentence as to the advantages enjoyed by the technically
workman. He says that "it is the rude or dexterous workman, rather than
the really skilled one, who is supplanted by machinery. Skilled labor
requires thinking; but a machine never thinks, never judges, never
discriminates. Though its employment does, indeed, enable rude laborers
to do many things now which formerly could only be done by dexterous
workmen, it is clear that its use has decidedly increased the relative
demand for skilled labor as compared with unskilled, and there is
abundant room for an additional increase, if it is true, as declared by
the most eminent authority, that the power now expended can be readily
made to yield three or four times its present results, and ultimately
ten or twenty times, when masters and workmen can be had with sufficient
intelligence and skill for the direction and manipulation of the tools
and machinery that would be invented."

The establishment of colleges and universities by the aid of national
grants has depended very much for their character upon the industrial
tendencies of the respective States, it being understood that the land
grants have principally been given to those of the newer States and
Territories which required development, although some of the
institutions of the older States on the Atlantic seaboard have also been
recipients of the same fund, which in itself only dates from an act of
Congress in 1862. In California and Missouri, both States abounding in
mineral resources, there are courses in mining and metallurgy provided
in the institutions receiving national aid. In the great grain-producing
sections of the Mississippi Valley the colleges are principally devoted
to agriculture, whereas the characteristic feature of the Iowa and
Kansas schools is the prominence given to industries.

We need not devote attention to the aims and arrangements of the
agricultural colleges proper, but will pass at once to those which deal
with the mechanical arts, dealing first of all with those that are
assisted by the national land grant. Taking them alphabetically, we have
first the State Agricultural College of Colorado, in the mechanical and
drawing department of which shops for bench work in wood and iron and
for forging have been recently erected, this institution being one of
the newest in America. In the Illinois Industrial University the student
of mechanical engineering receives practice in five shops devoted to
pattern-making, blacksmithing, moulding and founding, benchwork for
iron, and machine tool-work for iron. In the first shop the practice
consists of planing, chiseling, turning, and the preparation of patterns
for casting. The ordinary blacksmithing operations take place in the
second shop, and those of casting in the third. In the fourth there is,
first of all, a course of freehand benchwork, and afterward the fitting
of parts is undertaken. In the fifth shop all the fundamental operations
on iron by machinery are practiced, the actual work being carefully
outlined beforehand by drawings. This department of the University
consists, in point of fact, of three separate schools, destined to
qualify the student for every kind of engineering - mining, railway,
mechanical, and architectural. In addition to the shops and machine
rooms, there are well furnished cabinets of geological and mineralogical
specimens, chemical laboratories for assaying and metallurgy, stamp
mill, furnaces, etc., and, in fact, every known vehicle for practical
instruction. The school of architecture prepares students for the
building profession. Among the subjects in this branch are office work
and shop practice, constructing joints in carpentry and joinery, cabinet
making and turning, together with modeling in clay. The courses in
mathematics, mechanics and physics are the same as those in the
engineering school; but the technical studies embrace drawing from
casts, wood, stone, brick, and iron construction, turners' work,
slating, plastering, painting, and plumbing, architectural drawing and
designing, the history and aesthetics of architecture, estimates,
agreements specification, heating, lighting, draining, and ventilation.
The student's work from scale drawing occupies three terms, carpentry
and joinery being taught in the first year, turning and cabinet making
in the second, metal and stone work in the third. A more condensed
course, known as the builder's course, is given to those who can only
stop one year. The machine shop has a steam engine of 16 horse power,
two engines and three plain lathes, a planer, a large drill press, a
pattern shop, a blacksmith's shop, all of the machinery having been
built on the spot. The carpenter's shop is likewise supplied with
necessary machine tools, such as saws, planers, tenoning machine,
whittlers, etc., the power being furnished by the machine shop. At the
date of the last University report, there were 41 students in the
courses of mechanical engineering, 41 in those of civil engineering, 3
in mining engineering, and 14 in architecture. Tuition is free in all
the University classes, though each student has to pay a matriculation
fee of $10, and the incidental expenses amount to about $23 annually. He
is charged for material used or apparatus broken, but not for the
ordinary wear and tear of instruments. It should be mentioned that the
endowment of the Illinois Industrial University is from scrip received
from the Government for 480,000 acres of land, of which 454,460 have
been sold for $319,178. The real estate of the University, partly made
up by donations and partly by appropriations made in successive sessions
by the State of Illinois, is estimated at $450,000.

The Purdue University in Indiana, named after its founder, who gave
$150,000, which was supplemented by another $50,000 from the State and a
bond grant of 390,000 acres, also provides a very complete mechanical
course, with shop instruction, divided as follows:

Bench working in wood for 12 weeks, or 120 hours.
Wood-turning " 4 " " 40 "
Pattern-making " 12 " " 120 "
Vise-work in iron " 10 " " 100 "
Forging in iron and steel " 18 " " 180 "
Machine tool-work in iron " 20 " " 200 "

The course in carpentry and joinery embraces: 1. Exercising in sawing
and planing to dimensions. 2 Application, or box nailed together. 3
Mortise and tenon joints; a plain mortise and tenon; an open dovetailed
mortise and tenon (dovetailed halving); a dovetailed keyed mortise and
tenon. 4. Splices. 5. Common dovetailing. 6. Lap dovetailing and
rabbeting. 7. Blind or secret dovetail. 8. Miter-box. 9. Carpenter's
trestle. 10. Panel door. 11. Roof truss. 12. Section of king-post truss
roof. 13. Drawing model.

The course in wood turning includes: 1. Elementary principles: first,
straight turning; second, cutting in; third, convex curves with the
chisel; fourth, compound curves formed with the gouge. 2. File and
chisel handles. 3. Mallets. 4. Picture frames (chuck work). 5. Card
receiver (chuck work). 6. Watch safe (chuck work). 7. Ball.

In the pattern-making course the student is supposed to have some skill
in bench and lathe work, which will be increased; the direct object
being to teach what forms of pattern are in general necessary, and how
they must be constructed in order to get a perfect mould from them. The
character of the work differs each year. For instance, for the last
year, besides simpler patterns easily drawn from the sand, such as
glands, ball-cranks, etc., there were a series of flanged pipe-joints
for 2½ in. pipes, including the necessary core boxes; also pulley
patterns from 6 in. to 10 in. diameter, built in segments for strength,
and to prevent warping and shrinkage; and, lastly, a complete set of
patterns for a three horse-power horizontal steam engine, all made from
drawings of the finished piece. In the vise work in iron, the chief
requirements are these: 1, given a block of cast iron 4 in. by 2 in. by
1½ in. in thickness, to reduce the thickness ¼ in. by chipping, and then
finishing with the file; 2, to file a round hole square; 3, to file a
round hole into elliptical; 4, given a 3 in. cube of wrought iron, to
cut a spline 3 in. by 3/8 in. by ¼ in., and second, when the under side
is a one half round hollow - these two cuts involve the use of the cope
chisel and the round nose chisel, and are examples of very difficult
chipping; 5, round tiling or hand-vise work; 6, scraping; 7, special
examples of fitting. In the forging classes are elementary processes,
driving, bending, and upsetting; courses in welding; miscellaneous
forging; steel forging, including hardening and tempering in all its

It is worth mentioning that in the industrial art school of the Purdue
University there were 13 of the fair sex as students, besides one in the
chemical school, and two going through the mechanical courses just
detailed, showing that the scope of woman's industry is less limited in
America than in England. The Iowa State Agricultural College has also
two departments of mechanical and civil engineering, the former
including a special course of architecture. The workshop practice, which
occupies three forenoons of 2½ hours each per week, is, however, of more
general character, and is not pursued with such a regard to any special
calling as in the case of the Purdue University.

The Kansas State Agricultural College has a course of carpentry, though
designed rather more to meet the everyday necessities of a farmer's
life. In fact, all the students are obliged to attend these classes, and
take the same first lessons in sawing, planing, lumber dressing, making
mortises, tenons, and joints, and in general use of tools - just the kind
of instruction that every English lad should have before he is shipped

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Online LibraryVariousScientific American Supplement, No. 446, July 19, 1884 → online text (page 6 of 10)