930 FOODS AND FOOD ADULTERANTS. 
Sample No. 6,897 is a preparation of coffee with milk and sugar. This | 
sample contains .72 per cent caffeine. On the basis of Kénig’s mean 
percentage of caffeine two-thirds of a pound of average coffee is equal 
to about 1 pound of this preparation. This sample contains both tin | 
and copper in the following proportions per kilogram of the prepara- | 
tion: 
: Grams. 
Compounds of tin (calculated as metallic tin) 22222-22222 oe eee 0. 338 
Compounds of copper (calculated as metallic copper) ........-- eae te 2a 0. 023 
Judging from the observations of Dr. Van Hamel Roos the amount 
of tin in these samples is excessive and the risk of poisoning is great. 
The article quoted by Dr. Van Hamel Roos is well worth repreducing. 
TIN POISONING BY PRESERVES IN TIN CANS.! 
It seems to me that sufficient attention has not been paid to the impurities of pre- 
serves and to poisoning by compounds of tin. It is only during recent years that 
chemists and hygienists have given this subject serious consideration. It is the pur- 
pose of these pages to make known the facts heretofore proved and to point out cer- 
tain means for the prevention of like impurities. 
Messrs. Nuger and Bodliinder were first to call attention to the presence of rela- 
tively large amounts of tin in preserved asparagus. Sache found 70 milligrams of 
tin in 29 pieces of asparagus (see this Revue, 1, 91.) Likewise, Messrs. A. Menthe 
(Chem. News, July, 1871) and Schner (The Analyst, 1880, p.318) proved the presence 
of more or less important quantities of tin, not only in preserved fruit, but in other 
food materials, liquids, meat, and other preserved foods. 
Sedgwick cites for the first time a case of food poisoning which must be unques- 
tionably attributed to tin (Archives de Pharmacie, 1888). The poisoning was caused 
by pears prepared in a tinned stewpan. [A member of the congress, present session, 
informs me that a patient died from chronic metallic poisoning, resulting from the 
prolonged use of metalliferous preserved vegetables.] He afterwards examined sev- 
eral fruits preserved in tin cans and found very pronounced reactions for tin in all 
of them. 
Prof. Beckurts presented some very important data concerning the presence of tin 
in foods preserved in tin cans, at the session of the congress of German physicians 
held at Heidelberg, September 25, 1889. He emphasizes the importance of the sul- 
phide of tin, which is formed by the action of the albuminous matter of vegetables, 
meat, etc., on the tin of cans. At the current session, Dr. Nehring stated that he had 
proved the presence of 0.186 grams, 0.3146 grams, and 0.2269 grams, respectively 
of tin in three tin cans containing asparagus; whence the congress decided that 
the use of tin cans for the preservation of foods must be interdicted. 
During the preceding year Prof. Blarez commmunicated to the Journ. de Pharm. 
et de Chimie that he had found a considerable amount of tin in pears in tin cans. I 
am not able to confirm this result, as by repeated trials I only obtained traces of tin. 
I presume that the presence of a considerable quantity of salt has favored the solu- 
tion of tin in the sample examined by M. Blarez. 
Capitaine-Intendant Winckel reported to the Congress of Industrial Hygiene, held 
at Amsterdam, September 1890 (see No. 3 of this Revue), that 270 soldiers became ill 
after having eaten lettuce and meat preserved in tins. According to the determina- 
tions of Prof. Wefers Bettink, of Utrecht, the amount of tin present was from 19 to 
72 milligrams per kilogram. 
'Dr. Van Hamel Roos, Rev. Intern. des Falisfications, 4, 10, 179, translated by Mr. 
E. E. Ewell for this report. 
