COPPER-GREENING IN GERMANY. 



1069 



Hilger recalled the fact that in the case of these vegetables the copper entered the 

 body as an insoluble salt. When copper salts are added to albuminons liquids, even 

 though these be slightly acid, all copper is precipitated as an insoluble compound, 

 and for this reason copper when present in food is found in combination with the 

 albuminoids. He believed that copper was a normal constituent of the human body. 

 He was in favor of postponing action upon the question to the next yearly meeting. 



Dr. Koehler remarked that in fixing maximum amounts the pharmacopeia could 

 not be safely taken as a guide. He also stated that at the Strasburg exposition he 

 had seen some beautifully-colored green beans which derived their color from being 

 cooked in a copper kettle, an electric current being simultaneously passed through 

 them, the kettle serving as anode. Naturally large quantities of copper went into 

 solution. 1 



It was finally resolved that the meeting express no definite opinion, 

 but that the whole subject be postponed until the next yearly meeting. 



At the 1892 meeting, held at Regensburg August 2, Lehmann 

 reported on the copper question. Abstracted,-his report reads : 2 



The method used for the determination of copper was to moisten the organic mat- 

 ter under examination with sulphuric acid (occasionally with nitric), slowly dry, 

 burn in porcelain crucibles, leach the ash, and burn the carbon with soda and salt- 

 peter. The ashes were dissolved in dilute hydrochloric acid and precipitated with 

 hydrogen sulphid in weakly acid solution. The filtrate from the precipitate was 

 again treated with hydrogen sulphid. The sulphids, together with the filter on 

 which they were collected, were burned and the ash dissolved in hydrochloric acid 

 and treated with ammonia. The copper in the solution obtained was determined in 

 cases where it amounted to more than 2 nig by the method of De Haen (sodium 

 thiosulphate and potassium iodid). Amounts of copper lying between 2 mg and 

 0.3 nig were determined colorimetrically with ammonia. Less quantities were col- 

 orimetrically determined by ferrocyanid. Mach's hydrocyanic acid and gum guia- 

 cum method was not found advantageous, although it allowed the estimation of still 

 smaller amounts. Numerous trials with known amounts of copper were made as a 

 control, and nearly all tests were made in duplicate where the amount of material 

 made this possible. All reagents were copper-free. 



The results of Mayrhofer were quoted and commended. 



Determinations of the amount of copper in the livers and kidneys of various ani- 

 mals were made. The results were : 



French authors were quoted to show that sea animals often contain larger amounts. 



A dozen oysters are stated to contain an amount of copper lying anywhere between 

 36 and 108 mg, being a maximum of 2000 mgper kilo. 



As to the amount of copper present in artificially colored vegetables, Mayrhofer's 

 results were stated and also results drawn from other sources. The highest amount 

 on record was given as being bet ween 184 and 270 mgper kilo. The reporter had tasted 

 goods containing 244 mg, but could not detect copper. The taste of the peas was 

 wholly unaltered. Peas coppered by himself and containing 634 mg of copper per 



1 See page 1162. 

 3 Ber. bayr. Vertr. angew. Chem., 1892, 11, 16. 



