COPPER-GREENING IN FRANCE. 1051 



In the first-named process, chlorophyl is extracted from spinach or nettle with 

 caustic soda, precipitated in the form of a lake by potash alum, this dissolved in 

 sodium phosphate and the legumes plunged into the hot solution, from which they 

 take up the coloring matter. This process was patented in 1876 by MM. Lecourt 

 and Guillemare, who amended it in February, 1877, by proposing to replace the 

 alum by soluble lime and magnesium salts. Coloring by this process is irregular. 

 Some packages contain legumes which are of a good green color, but with others 

 this is not the case. Furthermore, the vegetables thus prepared have lost their 

 own delicate flavor to assume that of the nettle or, worse, that of the spinach, which 

 served as a source of chlorophyl. Besides all this the method is long and delicate 

 and difficult of execution. Again, the goods do not keep well, and the cans are 

 liable to explode, from internal fermentation. 



The calcium sucrate method was patented August 8, 1877, by MM. Possoz, Biardot, 

 and Lecuyer. They add to the can, before the final cooking, a liquid composed of 

 100 parts water, 3 parts sugar, 1 part sea salt, and 0.4 parts lime, with the idea of 

 precipitating a comparatively stable lime lake in the tissues of the vegetable. The 

 process gives variable results and has yet to stand the test of time. The color of 

 goods thus preserved is yellowish green. 



Garges' patent was taken out September 4, 1877. He treats the vegetables first 

 with sodium carbonate, then with alum. The results are unsatisfactory. 



The zinc process is still kept a secret, but in principle it consists in substituting 

 zinc chlorid for the copper sulphate used in the common process. It is in use by 

 one of the large factories. Vegetables treated by it assume a green tint or a natural 

 yellowish green, but they do not assume the French green, which the consumer 

 unhappily associates with these goods. This method of greening in our opinion 

 should be suppressed, since zinc is a substance whose presence in food in quantities 

 as large as those in which copper is customarily employed, can not be tolerated 

 without risk to public health. 



The liquor which surrounds the canned green peas, beans, etc., ordinarily con- 

 tains no copper. In some factories, however, it is a custom to add a little copper 

 sulphate to it, which is a reprehensible practice. The copper in the legumes is not 

 soluble in boiling water, but if artificially digested, copper passes into solution. 



A part of the copper dissolved in digestion is absorbed and part passes into the 

 excrement. It is necessary to consider the effect of the introduction into the 

 system of small and repeated doses of a metal reputed to be dangerous. In France, 

 the Conseil d'hygiene, consulted upon this point, has not hesitated to condemn the 

 use of copper salts, and the administration has accordingly taken measures to pre- 

 vent it. 



The salts of copper are poisonous: they are violent emetics. It is not easy, how- 

 ever, to poison an animal capable of vomiting. Numerous experiments 1 show that a 

 dog or even a man can swallow daily several grama of acetate, sulphate, phosphate, 

 or iodid of copper without experiencing any greater discomfort than a temporary 

 colic or fit of vomiting. However, it is not known whether small doses taken daily 

 can cause even these slight symptoms. 



Copper colic is described by some writers, admitted iu rare cases by others, and by 

 most authors totally denied. To-day it may be said that it is admitted to be au 

 unimportant phenomenon. Workers in copper absorb the metal directly by contact 

 and also in the state of dust. Often they become so saturated with it that their 

 eyes are turned green and the urine contains it. Galippe and his family lived for 

 more than a year on foods prepared in copper vessels and suffered no bad results. 



It would seem that in doses in which the metallic taste is not perceptible and in 

 which there is no emetic action the ingestion of copper salts leads to no immediate 

 inconvenience ; but it also seems that a longer experience and more rigorous observa- 



^oussaint, Bui. the"rap., 55, 237. Galippe, Theses de Paris, 1875. 



