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

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 whatever.