The Obermaier Machine, presently to be described, may also be used for dyeing loose cotton or wool. [Illustration: Fig. 13.--Obermaier Dyeing Machine.] #Dyeing Slubbing, Sliver or Carded Wool.#--It is found in practice that the dyeing of loose wool is not altogether satisfactory, the impurities they naturally contain interfere with the purity of the (p. 045) shade they will take. Then again the dyes and mordants used in dyeing them are found to have some action on the wire of the carding engine through which they are passed; at any rate, a card does not last as long when working dyed wools as when used on undyed cotton or wool fibres. Yet for the production of certain fancy yarns for weaving some special classes of fabrics it is desirable to dye the wool before it is spun into thread. The best plan is undoubtedly to dye the fibre after it has been carded and partly spun into what is known as slubbing, or sliver. All the impurities have been removed, the wool fibres are laid straight, and so it becomes much easier to dye. On the other hand, as it is necessary to keep the sliver or slubbing straight and level, no working about in the dye-liquors can be allowed to take place, and so such must be dyed in specially constructed machines, and one of the best of these is the _Obermaier Dyeing Machine_, which is illustrated in figure 13.--In (p. 046) the Obermaier apparatus dye-vat, A, is placed a cage consisting of an inner perforated metal cylinder, C, and an outer perforated metal cylinder, D; between these two is placed the material to be dyed. C is in contact with the suction end of a centrifugal pump, P, the delivery end of which discharges into the dye-vat A. The working of the machine is as follows: the slubbing or sliver is placed in the space between C and D rather tightly, so that it will not move about. Then the inner cage is placed in the dye-vat as shown. The vat is filled with the dye-liquor, which can be heated up by a steam pipe. The pump is set in motion, the dye-liquor is drawn from A to C, and in so doing passes through the material packed in B and dyes it. The circulation of the liquor is carried on as long as experience shows to be necessary. The dye-liquor is run off, hot water is run in to wash the dyed material, and the pump is kept running for some time to ensure thorough rinsing, then the water is run off, and by keeping the pump running and air going through a certain amount of drying can be effected. This machine works very well, and with a little experience constant results can (p. 047) be obtained. The slubbing or sliver may be scoured, bleached, rinsed, dyed, washed, soaped, or otherwise treated without removing it from the machine, which is a most decided advantage. [Illustration: Fig. 14.--Read Holliday's Yarn-dyeing Machine.]