By turning one of the cylinders, G, so as to present its aperture opposite that of the cooler, it instantly fills up with black. At this moment the whole column, from top to bottom, is set in motion. The bone-black, in passing through the undulations, is thrown alternately to the right and left until it finally reaches the coolers. This operation is repeated as many times as the cylinder is filled during the descent of one whole column, that is to say, about forty times. With an apparatus of the dimensions here described, 120 hectoliters of bone-black may be revivified in twenty four hours, with 360 to 400 kilogrammes of coke.--_Annales Industrielles_. * * * * * [Continued from SUPPLEMENT, No. 330, page 5264.] SOAP AND ITS MANUFACTURE, FROM A CONSUMER'S POINT OF VIEW. In our last article, under the above heading, the advantages to be gained by the use of potash soap as compared with soda soap were pointed out, and the reasons of this superiority, especially in the case of washing wool or woolen fabrics, were pretty fully gone into. It was also further explained why the potash soaps generally sold to the public were unfit for general use, owing to their not being neutral--that is to say, containing a considerable excess of free or unsaponified alkali, which acts injuriously on the fiber of any textile material, and causes sore hands if used for household or laundry purposes. It was shown that the cause of this defect was owing to the old-fashioned method of making potash or soft soap, by boiling with wood ashes or other impure form of potash; but that a perfectly pure and neutral potash soap could readily be made with pure caustic potash, which within the last few years has become a commercial article, manufactured on a large scale; just in the same manner as the powdered 98 per cent. caustic soda, which was recommended in our previous articles on making hard soap without boiling. The process of making pure neutral potash soap is very simple, and almost identical with that for making hard soap with pure powdered caustic soda. The following directions, if carefully and exactly followed, will produce a first-class potash soap, suitable either for the woolen manufacturer for washing his wool, and the cloth afterward made from it, or for household and laundry purposes, for which uses it will be found far superior to any soda soap, no matter how pure or well made it may be.