The preparation of the iodine monochloride solution presents no great difficulty, but it must be done with care and accuracy in order to obtain satisfactory results. There must be in the solution no sensible excess either of iodine or more particularly of chlorine, over that required to form the monochloride. This condition is most satisfactorily attained by dissolving in the whole of the acetic acid to be used the requisite quantity of iodine, using a gentle heat to assist the solution, if it is found necessary, setting aside a small portion of this solution, while pure and dry chlorine is passed into the remainder until the halogen content of the whole solution is doubled. Ordinarily it will be found that by passing the chlorine into the main part of the solution until the characteristic color of free iodine has just been discharged there will be a slight excess of chlorine which is corrected by the addition of the requisite amount of the unchlorinated portion until all free chlorine has been destroyed. A slight excess of iodine does little or no harm, but excess of chlorine must be avoided. [33] The melting point of oils may be determined in general according to the above procedure, taking into consideration the lower temperature required. PLANT AND MACHINERY Illustrations of machinery and layouts of the plant of a modern soap-making establishment. [Illustration: HOIST, LYE TANK, ETC.] [Illustration: MELTING-OUT TROUGH] [Illustration: LAUNDRY SOAP PLANT] [Illustration: DRYING RACK] [Illustration: SOAP KETTLE] [Illustration: REMELTER] [Illustration: CRUTCHER (Cross Section)] [Illustration: HORIZONTAL CRUTCHER] [Illustration: CRUTCHER] [Illustration: WRAPPING MACHINE (LAUNDRY SOAP)] [Illustration: SLABBER] [Illustration: CUTTING TABLE] [Illustration: AUTOMATIC POWER CUTTING TABLE] [Illustration: AUTOMATIC PRESS (LAUNDRY)] [Illustration: CUTTING TABLE (HAND)] [Illustration: CARTON WRAPPING MACHINE] [Illustration: DRYING RACKS] [Illustration: SOAP POWDER BOX] [Illustration: SCOURING SOAP PRESS] [Illustration: FRAME] [Illustration: SOAP POWDER EQUIPMENT] [Illustration: FLUFFY SOAP POWDER EQUIPMENT] [Illustration: SOAP POWDER MIXER] [Illustration: SOAP POWDER MILL] [Illustration: TOILET SOAP EQUIPMENT] [Illustration: TOILET SOAP DRYER] [Illustration: MILLING BOX] [Illustration: AMALGAMATOR] [Illustration: TOILET SOAP MILL] [Illustration: TOILET SOAP MILL] [Illustration: CHIPPER] [Illustration: PLODDER] [Illustration: HORIZONTAL CHIPPER] [Illustration: AMALGAMATOR (IMPROVED)] [Illustration: PRESS (LETTERING ON 4 SIDES OF CAKE)] [Illustration: Press (Foot)] [Illustration: Press (Foot)] [Illustration: PLODDER] [Illustration: AUTOMATIC PRESS (TOILET)] [Illustration: MULTIPLE CAKE CUTTER] [Illustration: CAKE CUTTER] [Illustration: CHIPPER] [Illustration: GLYCERINE DISTILLING PLANT] [Illustration: CRUDE GLYCERINE PLANT] [Illustration: H-A FATTY ACID DISTILLING PLANT] Appendix