Kusukela enkambisweni yokudubula, ukwengeza i-ferric oxide, i-manganese dioxide iyinqubo yendabuko, ngemva kokusabela ngokomzimba namakhemikhali, izokwakha i-silicate ezinzile, umzimba womuntu unempilo futhi uphephile; kusukela kwazalwa izinto zikagesi zobumba cishe iminyaka engama-20 yomlando, akukaze kube ...
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