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 Konig'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 : 



(irillllH. 



Compounds of till (calculated as metallic tin) 0. 338 



Compounds of copper (calculated as metallic copper) 0. 023 



Judging from the observations of Dr. Van Hamel Boos the amount 

 of tin in these samples is excessive and the risk of poisoning is great. 

 The article quoted by Dr. Van Hamel Eoos is well worth reproducing. 



TIN POISONING BY PRESERVES IN TIN CANS. 1 



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 tbe presence of rela- 

 tively large amounts of tin in preserved asparagus. Sadie found 70 milligrams of 

 tin in 29 pieces of asparagus (see this Revue, 1, 91.) Likewise, Messrs. A. Menlho 

 (Chein. News, July, 1871) and Schuer (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 dePharinacie, 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. Bockurts 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 ot 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. Blare/ comninmnicated 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 Rrvucl, that 270 soldiers became ill 

 after having oaten 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. 



1 Dr. Van Hamel Roos, Rev. Intern, dee Falislications, 4, 10, 179, translated I>\ Mr, 

 fi. E. Ewell for this report. 



