xiftke Argillaceous Iron-Ore. S73 



sable. The constitution of an ore can seldom be thoroughly 

 explored by the dry assay. On the contrary, the conclusions 

 at which the assayist arrives are of the most general nature. 

 The number of the individual ingredients in the ore, the cha- 

 racteristic nature, and still more, the relative amount of each 

 must always remain the subject of more or less doubtful con- 

 jecture. By the dry assay, the smelter possesses no test, to 

 enable him to appreciate the true composition of a scoria, ex- 

 cepting its fusibility, and its external and physical characters. 

 But as there are many earthy mixtures which, although very 

 dissimilar in reality, are yet converted in the furnace into scoriae 

 which do not distinguishably differ from each otlier in any of 

 the characters just mentioned, the assayist by fire, after all his 

 resources are exhausted, may still be left in perplexity respect- 

 ing the individual earthy constituents of his ore. 



For these reasons the assay, via humida, is frequently indis- 

 pensable, and, whenever sufficient time can be spared, it should 

 be always resorted to, as affording, in every case, the most 

 accurate and satisfactory exposition of the whole constitution 

 of an ore. We shall therefore proceed to state in detail a ge- 

 neral formula of analysis, via humida, by means of which the 

 true nature and amount of the constituents of the mineral that 

 is examined may be ascertained, even without employing any 

 uncommon degree of caution, to within xJo^^ P^^^^ of the 

 whole mineral. 



Take 100 grains * of the ore, either in powder or in small 

 pieces not larger than a grain of wheat, and put it into a ves- 

 sel of glass or platinum, containing a mixture of one ounce 

 measure of concentrated muriatic acid, with two ounce mea- 

 sures of water. The mineral will immediately begin to pass 

 into solution with effervescence. When the action in the cold 

 appears to have terminated, digest the mixture upon a sand- 

 bath, in a temperature scarcely exceeding 100°, for about four 

 hours. It will now be found that, by this treatment, the 

 whole of the metallic oxides and earths which existed in the 



* When it is the principal object of the analysis to determine the precise 

 quantity of metal contained in the ore, and when the nature and amount 

 of each of its extraneous ingredients are of minor importance, the assayist 

 may obtain accurate results by operating with fifty or even with only 

 twenty grains- , -- 



