COPPER-GREENING IN GERMANY. 1071 



appearance of the goods. No disadvantage is found in the addition of the copper 

 as long as the addition is a small one. If the amount be larger slight bad results 

 may be produced, but very bad results are not to be feared even with very careless 

 work. In the opinion of the reporter 25 mg per kilo are insignificant from a 

 hygienic point of view, but 100 mg are not altogether a matter of indifference. A 

 line at which injury to health begins, however, can not be drawn. 



In making a final conclusion upon this point purely practical questions should 

 be considered, and it must be left to the technical expert to decide whether the 

 commercial advantages of allowing the use of this substance overbalance the possible 

 danger of the goods suffering discredit in the minds of those ignorant of the subject. 

 It is, however, best to fix a low limit like 25 mg. It may be finally reiterated that 

 hygienically there is nothing against the concession. 



DISCUSSION. 



In the subsequent discussion Mayrhofer spoke of the results of Tschirch. He 

 further remarked that there was an opinion that copper was unnecessary, inasmuch 

 as there were other non-injurious colors which could serve the same purpose. This 

 was true for many substances, but not for canned foods. A coloring matter has been 

 sold in Vienna for this purpose, but it did not resist the action of acids. 



Hilger remarked that in some investigations on marine animals he had frequently 

 discovered copper. In some of the Tunicatse he had discovered 0.02 per cent copper 

 (200 mg per kilo). In salt and fresh water crabs he had also detected it. Copper is 

 a normal constituent of the human body. In the neighborhood of Treuchtlingen a 

 a copper-poisoning case occurred. The patient ate some soup and died in a few 

 hours. The soup contained a largo amount of copper. A fatty soup standing in 

 clean scoured copper vessels can absorb considerable metal. In one case this 

 amounted to 0.163 per cent copper. 



Kayser remarked that, in discussing the presence of copper in preserved foods, it 

 was irrelevant whether it was in part of natural origin or all artificially added, He 

 was of the opinion that the limit should be placed at 25 mg and that this limit 

 should not be overstepped. 



Borgmann mentioned the danger of copper contamination from Bunsen burners in 

 carrying out tests for the metal. 



Lehmann remarked that he had been on the watch for this danger, but had found 

 no evil results from the ordinary brass Bunsen burner. 



Von Kerschensteiuer said that it had long been known to physicians that copper 

 was a normal constituent of the body, either in small amounts or in larger accumula- 

 tions. It is also a piece of familiar knowledge that occasionally copper exerts a 

 poisonous action. It was, however, now evident that copper salts administered up 

 to a certain amount were not injurious, and in the future cases of illness resulting 

 from food which was found to contain copper would be regarded in a different light. 

 It is easily conceivable, however, that a small dose of copper administered in the 

 form of one organic combination might have a different action from that of the 

 same dose in another shape. Maximal allowable limits might be different for 

 different substances. 



Kammerer inquired if the copper occasionally present in mineral waters would be 

 likely to exert a different action from that present in canned foods. 



Halenke thought caution and further knowledge were necessary in taking a stand 

 on the matter of maximum limits, in view of the great fear which had hitherto been 

 entertained of copper. 



Kayser was of the opinion that the time had come to take a definite stand in the 

 matter. 



Lehmann remarked that time was expensive, and that since 1818 30 or 40 authors 

 had handled the subject. Cuprophobia dated from the middle of the previous cen- 

 tury, but he thought it was without foundation. As to the impression that one 



