RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Paris green, composition and adulterations, B. B. Ross {Ala- 

 bama College Sta. Bui. 58, pp. 7). — The history and character of Paris 

 green are discussed. According to Ehrmann pure Paris green contains 

 31.29 per cent of copper oxid, 58.65 per cent of arsenious acid, and 10.06 

 l)er cent of acetic acid. Analyses are given of 6 samples collected in 

 the State and 1 from a chemical house in New York. Six of the sam- 

 ples showed arsenious acid ranging from 53,13 to 59.71 i^er cent, " and 

 no traces of adulteration or attempts at adulteration were detected." 

 A seventh sample, although resembling Paris green except in bright- 

 ness of tint, contained no copper or arsenic. Prussian blue and chrome 

 yellow were found, with a large quantity of inert matter, as clay, chalk, 

 etc. 



" On taking a small portion each of Prussian blue and chrome yellow and mixing 

 with a large quantity of clay or chalk it was found that a product corresponding 

 almost precisely in color to the material examined could be produced, and it was 

 found quite easy to imitate the normal shade of color of Paris green, though the 

 brightness of tint would be lacking. It was estimated that a material of this char- 

 acter could be manufactured at a cost not exceeding 1 ct. per pound, while a high 

 grade Paris green frequently costs above 20 cts. per pound, the fraudulent manufac- 

 turer being thus able to dispose of his product at an enormous jirofit." 



The method followed at the station for determining arsenious acid in 

 Paris green is described. 



On the determination of the bromin absorption of fats gravi- 

 metrically, O. Heuner {Analyst, 20 {1895), Mar., pp. 49-53).—'-^ The 

 present contribution is merely intended as a study and not as a proposed 

 method, although I believe that in some cases it may be found conven- 

 ient and that it may afford another factor in judging of the constitution 

 of an oil." The process is based on the fact that if bromin is added to 

 an oil without the intervention of a solvent, combiuation takes place 

 immediately, often with a rather violent reaction, but if diluted with- a 

 suitable solvent, as chloroform, the action is moderated but equally 

 complete. 



" I operate as follows in order to obtain the bromo compounds in a state fitted for 

 weighing : A small, wide-mouthed fat iiask is carefully weighed, and from 1 to 3 gm. 

 of the fat to be tested iutrodiiced into it. These are dibsolved in a few cc. of 

 chloroform, and then ]iure bromin is added, drop by drop, until the bromin is 

 decidedly in excess. Both the chloroform and bromin mustbe previously tested in a 

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