Cov tshuaj reagents tau siv dav hauv kev lag luam, kev ua liaj ua teb, kev kho mob thiab kev noj qab haus huv, kev tshawb fawb txog lub neej, kev tshuaj xyuas thiab kev cais tawm, kev tiv thaiv ib puag ncig, Kev tsim hluav taws xob, kev tiv thaiv hauv teb chaws thiab kev ua tub rog, kev tshawb fawb tshawb fawb thiab txhua qhov chaw ntawm kev lag luam hauv lub teb chaws, tab sis yog dab tsi "chemical reagent" thiab nws muaj dab tsi, nws tseem yog ib qho nyuaj rau muab qhov tseeb txhais ntawm nws. Nyob rau hauv thaum ntxov hnub, tshuaj reagents tsuas yog xa mus rau "cov tshuaj dawb huv siv nyob rau hauv tshuaj ntsuam xyuas thiab tshuaj thwmsim los txiav txim seb muaj pes tsawg leeg los yog muaj pes tsawg leeg ntawm cov tshuaj". Tom qab ntawd, nws tau nthuav dav kom suav nrog "cov tshuaj siv los ua kom tiav cov tshuaj tiv thaiv kab mob", thiab lo lus "chemical reagent" raug xa mus rau cov tshuaj uas tau dhau los ntawm pawg no. Nws tau raug sib cav tias "cov tshuaj siv hauv kev sim kev tshawb fawb" tuaj yeem hu ua "chemical reagents". Lub ntsiab txhais ntau dua ntawm tus neeg sawv cev tshuaj tuaj yeem yog: cov khoom sib txuas lossis cov ntsiab lus ntawm ntau qib purity siv hauv cov tshuaj ntsuam xyuas tshuaj, tshuaj ntsuam xyuas tshuaj, kev tshawb fawb tshuaj, thiab lwm yam kev sim.