390 PURPLE DYEING, ANCIENT AND MODERN. 



tliey complained tliat it -was of so many different shades that the various trades 

 and professions whicli use the article were unnecessarily embarassed in the 

 choice among so many gradations of color ; for while the German manufacturers 

 exhibited twenty different tints, the French furnished but eight. To this Ger- 

 mans rc])Iied, that in supplying so many different shades of the color they but 

 compliixl with the public wish. Yet, nothing can be plainer than that in every- 

 thing relative to color and cognate matters of taste, it is not the jtublic which 

 prescribes, but the artist, who elicits the artificial want. It was Phidias who 

 created the Atlienian taste for the surpassing beauty of the Phidian sculpture. 



Up to 1849, France had only two manufactories of ultramarine. In that year 

 a third was added, in Alsace, (Zuber & Co., at Rixheim,) which deserves men- 

 tion with that of Guimct, who still sustains his long-established reputation. 

 To such an extent is the manufacture of p;iper-liangings carried on at Rixheim, 

 that the manufjxcture of colors might appear a merely accessory and subordi- 

 nate branch. But such is not the fact ; for, besides supplying the home demand, 

 that factory exports to a very large amount. As long ago as 1849, the estab- 

 lishment employed 500 laborers, at an expense of $43,333. And the motive 

 power consisted of 44 machines, exerting, in the aggregate, a sixty .two horse 

 power. 



As mentioned above, Gmelin's mode of using only the very purest raw 

 material has been abandoned. But, though the ultramarine 'mamifactured on 

 his method was undoubtedly more costly, it is no less certain that it was also 

 far superior in color to all other sorts of ultramarine. Economical manufacture 

 is now sought in a variety of ways. A white German clay found in many parts 

 of the country, and known to the trade under the name of "lanziu," is the 

 most commonly nmde use of. White porcelain earth is preferable on account 

 of its greater purity. A small portion of magnesia and lime is of no conse- 

 quence; but if iron be present in greater proportion than one per cent., the utmost 

 care is requisite to produce an even tol(>rablc color. All foreign matters of a 

 tangible kind are carefully removed by repeated washings ; the clay is then 

 dried, made red-hot, and reduced to a fine powder in a mill or stamper. These 

 preparatory processes, simple as they appear to be, are in reality of great im- 

 portance, and the mechanical contrivances for rendering them perfectly effectiA'-e 

 are among the most ingenious, as well as the most costly, of all the machinery 

 employed in the manufacture. To the ground or crushed mass there arc now 

 added sulphuric natron, soda, sulphur, and coal or charcoal ; the whole having 

 been previously reduced to the finest possible powder. If coal instead of char- 

 coal be used, such must be selected as after combustion leaves the smallest 

 quantity of ashes. Sometimes rosin is used instead of coal, and, being discom- 

 posed by the heat, answers all the purpose of the mineral. Heated together, 

 these various materials become fused into one mass. Upon the process thus far 

 described, and, especially upon the exactly proper proj)ortion of each of the 

 materials, the result greatly depends. 



With regard to one point in the procedure there is a wide difference between 

 the French and the German manufacture. In the latter, Glauber salt or a mix- 

 ture of that salt and natron is always used; in the former, only soda. The 

 German mode is the more economical, because the sulphuric acetical natron is 

 by the agency of the coal converted into sulphuric natrium, and thus the sul- 

 phur can be wholly or partially dispensed with if soda be added at the same 

 time. It is true that a somewhat greater quantity of coal will be required, 

 but there can be no comparison between its price and that of sulphur. As to 

 the result, it does not seem that the one or the other method is very greatly 

 preferable. 



There is great difference in the proportions of the several components of this 

 mixture ; but the following may serve as a general rule : 



