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在用亚硝酸钴钠测定植物或土壤中钾的含量的时候,一般所得到的 K_2NaCo(NO_2)_6沉淀,在组成上并不固定,由于温度和手续的不同,其含钾量常不能达到17.216%的理论值。因此各个试验室中,常采用自己的经验数值。目前所通用的沉淀温度,有的在冰箱中保持在0℃以下,有的保持在20℃,有的在水浴上蒸发至糊状。根据我们的经验,Wilcox 氏法并不能得到如原作者所述的数值,其误差常低于理论值6%左右,同时分析手续难于控制如所要求保温20℃,在实
In the determination of potassium in plant or soil with sodium nitrite, the K_2NaCo (NO_2) __6 precipitate obtained is not fixed in composition, and its potassium content often can not reach 17.216 due to different temperature and procedure % Theoretical value. Therefore, each laboratory, often using their own experience value. Currently used precipitation temperature, some kept in the refrigerator below 0 ℃, and some maintained at 20 ℃, and some evaporated to a paste on the water bath. According to our experience, Wilcox’s method can not obtain the value as described by the original author, and the error is often less than 6% of the theoretical value. Meanwhile, the analysis procedure is difficult to control as required.