OBSERVATIONS ON "TINNING" COOKING I'OTS IN INDIA.
By
J. B. Hamilton, M.
D., Surg eon-Major,
A. M. D.
Tinning the cooking utensils in common use in India, is a question that often gives rise to a considerable amount of trouble in consequence of the "knlai" wearing off very rapidly, and exposing the surface of the copper when the work is badly or carelessly done. The blame is usually attributed either to an insufficient coating of tin being applied, or to the cooks cleaning the surface of the utensils with sand and thus laying bare the The result is probably a committee, which either copper. throws the blame on the cooks or the tinning contractor, and causes much trouble to the regimental authorities and the commissariat department A short time ago when inspecting the hospital cooking utensils which had been tinned two days before, I observed they were all of a dull greyish colour, and had not the bright silvery appearance of tin. I suspected that some other metal had been
mixed with the tin used for
"
kalaiing," and on rubbing the sursuspected degcliies with a clean cloth stretched tightly over the finger,- I obtained the unmistakeable stain of lead, and could even detect the bright specks of the metal in the face of the
fibres of the cloth. On making a further examination of the Battery utensils, I found them in, if possible, a worse state, and on scraping and chemically testing the surface, I fouiul that the so-called "tin" was about one-half lead. In this case the contractor lost his and was fined the entire amount of his security by thecommissariat officer. On making enquiries from the commissariat sergeants and the medical subordinates, I find this use of lead is much more
contract
common
being
suspected, and though the fact of the tinning frequently apparent, I believe the real cause ia indeed thought of, or, if suspected, proved against
than is
bad is
very seldom the offenders. I have
frequently
in India seen cases of colic that made me
suspect the presence of lead, and in
more
than
one
instance
I
THE INDIAN MEDICAL GAZETTE.
234 have asked the
men
if
they
had
been
using paint, painting
the
for instance, little suspecting what I now believe to have been the real cause. If cooking utensils are tinned with an admixture of lead, the following are the dangers to which those who eat food cooked in
carriages
gun
such vessels are liable : IsiJ.?The lead being exposed to the air comes off in the form of a sub-oxide, and combining with the acids in the stomach ?
will be absorbed.
2nd.?Galvanic action from the contact with the copper will the lead to be detached. 3rd.?Men frequently have stews and other dishes cooked with pickles and vinegar; the lead is thus dissolved and is consumed in the form of the acetate. cause
4th.?In consequence of the
galvanic
action set up, and the
greater softness of the mixture of lead and tin than pure tin, the " kalaiing" wears off rapidly and the copper becomes exposed, causing a further liability to danger from the oxidisation of the latter metal. Itis well known that lead is a cumulative poison, and it stands of the metal in reason if men absorb a very small quantity their food daily, even though it may not cause positive evidence of lead poisoning, the general health will bs affected, and anomato
lous symptoms will arise. Tinning to be properly done should be effected as follows The surface of the utensil having been thoroughly cleaned from oxide by heating it, a little sal-ammoniac (naushadar) is rubbed on,
which converts the oxide into the volatile chloride of copper;
a little resin is then sprinkled on the metallic surface to protect it from oxidisation, and the tin (ranga) being rubbed on while the vessel is still hot melts, and is spread evenly with tow or cotton over the whole surface, giving it a bright silver-like
appearance. The question here arises,
why is not this done in the regimental workshops? Any intelligent soldier could learn the process in five minutes, and it would certainly add to the independence of the army on service; this very point cropped up at Perak, where, I am informed, the cooking pots were frequently
bare of tin in consequence of the desertion or death of the men sent from India to do the work. A small quantity of tin, salammoniac, and resin, would render a corps quite independent of native assistance, and would ensure purity of material and satis-
factory workmanship. The reasons for the adulteration are evident?the price of tin in the bazars averaging Re. 1-8, and that of lead 5 annas per seer. It cannot be pleaded that it is easier to use lead than tin, as the former melts at a temperature of 617? F. while the latter melts at 442? F. The tin
as sold in the bazars is generally in thin strips, cracks when bent, is of a silvery appearance and of a low specific gravity, viz., 7*2; when lead is mixed with tin it bends more
easily, and rapidly assumes a greyish colour when exposed to air : it will also mark paper with the well-known lead mark, while tin will only crease the surface.
The simplest way to test the admixture of lead in the "kalai" is to dean the surface and rub it hard with a cotton cloth stretched tightly over the fore-finger, a slight stain will
off from the first few rubs, even though the tin be after a few applications the cloth will remain quite but pure, clean, while, if lead be mixed with it, the more it is rubbed the blacker will be the stain; spiculse of lead also will be visible come
in
a
strong light.
This test will be primA facia evidence of the presence of lead, but chemical analysis will prove it beyond a doubt. The best plan is to scrape the surface with a knife, and putting a few grains of the metal thus obtained in a test tube, add a few drops of water and about double the quantity of nitric acid; a nitrate of lead is formed with ebullition, and the
[September 1,
1876.
metallic tin is left undissolved as a dark grey powder. If a few drops of the above solution be added to a solution of iodide of potassium, the yellow iodide of lead is thrown down ; other tests can of course be applied, but the one just mentioned is the
simplest, and is perfectly satisfactory. If a quantitative analysis be desired, let the powder be weighed before the addition of the acid, wash, dry, and weigh the residuum, deduct the latter from the original total, and the amount of lead will be the result, or at all events so closely approximate as to
be
sufficiently
accurate
for practical purposes.
The
dangers of lead poisoning in India are all the greater, because unsuspected, and I am of opinion, I have seen many cases in India of colic which might have been traced to this cause ; no doubt if men were exposed to the deleterious influence for any length of time, further symptoms would be developed.
To make matters worse, the soldier does not even escape when hospital, but is then, if possible, more liable to the danger than in barracks. I have little doubt that if the cooking utensils in use in all
in
the stations in this
presidency could be examined chemically, large proportion would be found tinned with this poisonous alloy, instead of with the pure tin, contracted and paid for. JP.S.?Since writing the above report for submission to the Surgeon-General, I have received some valuable information from Deputy Surgeon-General Kendall of the Allahabad circle, a
very
who tells
me he has discovered that a mixture of tin of lead f of a tola, and zinc |th of a tola is smelted toand used for "kalaiing" at Allahabad. The composition goes by the name of Taki or Tainka, and i3 also used for repairing copper vessels. Lead canuot be used alone, and the zinc is added to make the mixture harder. Tin is
tola, gether a
added
only in sufficient quantities to give the silver-like appearance when first applied. Dr. Kendall further adds that the use of this mixture was discovered in Paris by some of the French physicians, and that one of the of a symptoms
patient poisoned by this lead "kalai" was loss of memory, &c., &c. The discovery of lead in very minute quantities in soda water by Dr. McNaraara created quite a sensation out here, but I think it will be allowed that lead in one's daily food is a far worse danger, as comparatively a small section of the community is exposed to the danger of poisoned effervescing waters, while every one, from the infant to the adult, is liable to suffer from badly tinned cooking pots. Perhaps the subject may be of sufficient importance to the profession in India, to warrant a hope that a general testing of the "kalai" in use at the different stations may be made. The physical properties of tin are so unmistakeably different from lead, that the most telling the difference. C awn poke,
inexperienced chemist
August 1876.
cannot fail in
By
J. B. Hamilton, M.
D., Surg eon-Major,
A. M. D.
Tinning the cooking utensils in common use in India, is a question that often gives rise to a considerable amount of trouble in consequence of the "knlai" wearing off very rapidly, and exposing the surface of the copper when the work is badly or carelessly done. The blame is usually attributed either to an insufficient coating of tin being applied, or to the cooks cleaning the surface of the utensils with sand and thus laying bare the The result is probably a committee, which either copper. throws the blame on the cooks or the tinning contractor, and causes much trouble to the regimental authorities and the commissariat department A short time ago when inspecting the hospital cooking utensils which had been tinned two days before, I observed they were all of a dull greyish colour, and had not the bright silvery appearance of tin. I suspected that some other metal had been
mixed with the tin used for
"
kalaiing," and on rubbing the sursuspected degcliies with a clean cloth stretched tightly over the finger,- I obtained the unmistakeable stain of lead, and could even detect the bright specks of the metal in the face of the
fibres of the cloth. On making a further examination of the Battery utensils, I found them in, if possible, a worse state, and on scraping and chemically testing the surface, I fouiul that the so-called "tin" was about one-half lead. In this case the contractor lost his and was fined the entire amount of his security by thecommissariat officer. On making enquiries from the commissariat sergeants and the medical subordinates, I find this use of lead is much more
contract
common
being
suspected, and though the fact of the tinning frequently apparent, I believe the real cause ia indeed thought of, or, if suspected, proved against
than is
bad is
very seldom the offenders. I have
frequently
in India seen cases of colic that made me
suspect the presence of lead, and in
more
than
one
instance
I
THE INDIAN MEDICAL GAZETTE.
234 have asked the
men
if
they
had
been
using paint, painting
the
for instance, little suspecting what I now believe to have been the real cause. If cooking utensils are tinned with an admixture of lead, the following are the dangers to which those who eat food cooked in
carriages
gun
such vessels are liable : IsiJ.?The lead being exposed to the air comes off in the form of a sub-oxide, and combining with the acids in the stomach ?
will be absorbed.
2nd.?Galvanic action from the contact with the copper will the lead to be detached. 3rd.?Men frequently have stews and other dishes cooked with pickles and vinegar; the lead is thus dissolved and is consumed in the form of the acetate. cause
4th.?In consequence of the
galvanic
action set up, and the
greater softness of the mixture of lead and tin than pure tin, the " kalaiing" wears off rapidly and the copper becomes exposed, causing a further liability to danger from the oxidisation of the latter metal. Itis well known that lead is a cumulative poison, and it stands of the metal in reason if men absorb a very small quantity their food daily, even though it may not cause positive evidence of lead poisoning, the general health will bs affected, and anomato
lous symptoms will arise. Tinning to be properly done should be effected as follows The surface of the utensil having been thoroughly cleaned from oxide by heating it, a little sal-ammoniac (naushadar) is rubbed on,
which converts the oxide into the volatile chloride of copper;
a little resin is then sprinkled on the metallic surface to protect it from oxidisation, and the tin (ranga) being rubbed on while the vessel is still hot melts, and is spread evenly with tow or cotton over the whole surface, giving it a bright silver-like
appearance. The question here arises,
why is not this done in the regimental workshops? Any intelligent soldier could learn the process in five minutes, and it would certainly add to the independence of the army on service; this very point cropped up at Perak, where, I am informed, the cooking pots were frequently
bare of tin in consequence of the desertion or death of the men sent from India to do the work. A small quantity of tin, salammoniac, and resin, would render a corps quite independent of native assistance, and would ensure purity of material and satis-
factory workmanship. The reasons for the adulteration are evident?the price of tin in the bazars averaging Re. 1-8, and that of lead 5 annas per seer. It cannot be pleaded that it is easier to use lead than tin, as the former melts at a temperature of 617? F. while the latter melts at 442? F. The tin
as sold in the bazars is generally in thin strips, cracks when bent, is of a silvery appearance and of a low specific gravity, viz., 7*2; when lead is mixed with tin it bends more
easily, and rapidly assumes a greyish colour when exposed to air : it will also mark paper with the well-known lead mark, while tin will only crease the surface.
The simplest way to test the admixture of lead in the "kalai" is to dean the surface and rub it hard with a cotton cloth stretched tightly over the fore-finger, a slight stain will
off from the first few rubs, even though the tin be after a few applications the cloth will remain quite but pure, clean, while, if lead be mixed with it, the more it is rubbed the blacker will be the stain; spiculse of lead also will be visible come
in
a
strong light.
This test will be primA facia evidence of the presence of lead, but chemical analysis will prove it beyond a doubt. The best plan is to scrape the surface with a knife, and putting a few grains of the metal thus obtained in a test tube, add a few drops of water and about double the quantity of nitric acid; a nitrate of lead is formed with ebullition, and the
[September 1,
1876.
metallic tin is left undissolved as a dark grey powder. If a few drops of the above solution be added to a solution of iodide of potassium, the yellow iodide of lead is thrown down ; other tests can of course be applied, but the one just mentioned is the
simplest, and is perfectly satisfactory. If a quantitative analysis be desired, let the powder be weighed before the addition of the acid, wash, dry, and weigh the residuum, deduct the latter from the original total, and the amount of lead will be the result, or at all events so closely approximate as to
be
sufficiently
accurate
for practical purposes.
The
dangers of lead poisoning in India are all the greater, because unsuspected, and I am of opinion, I have seen many cases in India of colic which might have been traced to this cause ; no doubt if men were exposed to the deleterious influence for any length of time, further symptoms would be developed.
To make matters worse, the soldier does not even escape when hospital, but is then, if possible, more liable to the danger than in barracks. I have little doubt that if the cooking utensils in use in all
in
the stations in this
presidency could be examined chemically, large proportion would be found tinned with this poisonous alloy, instead of with the pure tin, contracted and paid for. JP.S.?Since writing the above report for submission to the Surgeon-General, I have received some valuable information from Deputy Surgeon-General Kendall of the Allahabad circle, a
very
who tells
me he has discovered that a mixture of tin of lead f of a tola, and zinc |th of a tola is smelted toand used for "kalaiing" at Allahabad. The composition goes by the name of Taki or Tainka, and i3 also used for repairing copper vessels. Lead canuot be used alone, and the zinc is added to make the mixture harder. Tin is
tola, gether a
added
only in sufficient quantities to give the silver-like appearance when first applied. Dr. Kendall further adds that the use of this mixture was discovered in Paris by some of the French physicians, and that one of the of a symptoms
patient poisoned by this lead "kalai" was loss of memory, &c., &c. The discovery of lead in very minute quantities in soda water by Dr. McNaraara created quite a sensation out here, but I think it will be allowed that lead in one's daily food is a far worse danger, as comparatively a small section of the community is exposed to the danger of poisoned effervescing waters, while every one, from the infant to the adult, is liable to suffer from badly tinned cooking pots. Perhaps the subject may be of sufficient importance to the profession in India, to warrant a hope that a general testing of the "kalai" in use at the different stations may be made. The physical properties of tin are so unmistakeably different from lead, that the most telling the difference. C awn poke,
inexperienced chemist
August 1876.
cannot fail in
