March 14, 1913] 



SCIENCE 



403 



The fact that the non-ionie copper in the 

 phyllocyanate is practically inert physio- 

 logically has been noticed by others. Ref- 

 erence here may be made to the work of 

 Tschirsch/* Spiro"" and Brandl.^^ These 

 writers agree that other compounds of cop- 

 per have a much more marked effect. 

 From these other combinations, as well as 

 from imperfectly coppered vegetables, the 

 metal may reach the liver and other organs 

 and in time produce a marked effect. In 

 a series of experiments by Chittenden this 

 absorption has been clearly shown. As 

 long as it is not practically possible to 

 limit the use of copper in greening to the 

 youngest vegetables only, and in a speci- 

 fied small amount, it would seem that it 

 might be well to prohibit its use altogether 

 in foods, where, indeed, it serves no useful 

 purpose bej'ond imparting a bright green 

 color. 



SULPHUROUS ACID 



Sulphurous acid is used in two essen- 

 tially different ways in the treatment of 

 food products. First, in the free state or 

 the oxide, and secondly, as a salt, usually 

 sodium sulphite, but sometimes the bisul- 

 phite. Some years ago there was for a 

 time a limited application of the true hypo- 

 sulphite, but this seems to have been aban- 

 doned. Sulphurous acid found its first 

 uses in this connection in the protection of 

 must before fermentation, and in the rack- 

 ing off or transfer of wines from one vat 

 to another, or just before bottling. These 

 uses are still in vogue, and other uses have 

 been introduced, especially in the clarifica- 

 tion of cane juices before boiling down for 

 sugar, and in the treatment of certain 



" ' ' Das Kupfer vom Standpunkte der gericht- 

 lichen Chemie, Toxikologie vmd Hygiene," Stutt- 

 gart, 1893. 



^ Muench. Med. Wochenschr., 56: 1, 1070. 



^ Arh. aus dem hais. Gesundheitsamt, 13: 104, 

 1897. 



fruits in the sun-drying process. Within 

 comparatively recent times the application 

 of sodium sulphite in some of the minor 

 meat industries and in the canning of cer- 

 tain vegetables was introduced. 



It will be seen at a glance that we have 

 here two rather distinct conditions. In 

 the application of the sulphurous acid in 

 the sugar, wine and fruit industries there 

 is finally a pretty complete combination 

 of the product with the sugars to form the 

 aldehyde compounds, from which the sul- 

 phite is gradually oxidized. These carbo- 

 hydrate-containing substances hold also 

 certain organic salts, the acids of which are 

 in part displaced by the sulphurous acid. 

 The protein and fatty substances of meats, 

 however, are in themselves inert toward 

 sodiism sulphite, and the latter remains 

 unmodified or combined. The fats, in 

 addition, protect the sulphite from rapid 

 oxidation. Among food chemists there 

 seems to be a practical recognition of this 

 distinction in the active condition of the 

 two classes of sulphured products, and the 

 question of permissibility of use has been 

 advanced generally with reference to the 

 sulphites, rather than as concerns the car- 

 bohydrate combinations. 



As observed with relatively large inges- 

 tions all these products exert, of course, a 

 somewhat toxic action, and the toxicity of 

 the carbohydrate combinations seems to 

 run parallel with their rates of dissocia- 

 tion as aldehyde compounds. For the pure 

 aldehydes the rate is rather rapid in the 

 glucose compound, as the lengthy investi- 

 gations carried out by Rost and Franz and 

 by Kerp have shown." But in their ex- 

 periments the rate of dissociation of the 

 glucose aldehyde compound is undoubtedly 

 far greater than would be the case in the 

 commercial combinations of fruits and 



" Arb. aus dem kais. Gesundheitsamt, 21 : 1904. 



