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Änalyßs. ' 483 iron ät bottom ; let the melted mafs be pul- verized, and rhrown into a glafs veffel filled with wacer; it will cxhibit various colours, and, in a fe.w days, fubfide in a brovvn mafs ; pour off the filtred water, and treat this brown mafs with dilute nitrous acid,' adding fugar, frorn time to time, or, what is ftill bettet, lulphureous acid, the calx of m3nganefe will foon difl’olve, preci- pitate the folution with mild foda, and weigh the white precipitate, gently dried, of which 180 grains denote ioo of the regulus of manganefe ; the weiffht of iron is to be determined as in No» O 3°* 95. If the folution contains other metallic fubltances, it feenis beft, after expulfion of excefs of acid, and fufficient dilution, to precipitate them by crylbHized Pruffian alkali, made as di- rcfted in the fcquel, the quantity employed lliould be known, and nöted ; if the precipitation be flow, the folution fhould be warmed, or evcrt hcated nearly toboiling, fpiritof winebeingadded, and often filtred. 1 fhall fuppofe the precipi tate, no'.v obtained, to contain the different me tallic fubflanccs, it fhould be wafhed, and the firfl waflfings added to the folution, as thele wafliings contain part of the folution of the eart'ns entangled in the precipitate, but wlien the wafh- ings ccafe to be acid, or when it is pcrceivkl that, when mixed with the folution of iron they produce a blue, they fhould ceafe, otherwife much of the precipitate would be carried off. When wafhed, it fhould be thoroughly dried, hcated to red 11 cfs, and weighed. 96. ln this (täte the calces fuppofcd to contain niclcel, cobalt, and copper, are to be treated with cauflic volatile alkali, which will turn blue, I i 2 with