WORKING MODEL OF A PLANT NITRATOR In October' the writer outlined briefly the system of instruction employed a t Girard College, whereby advanced students or groups of students are allowed to work out projects dealing with commercial processes. In that article a miniature contact-process sulfuric acid plant, designed and built entirely by students, was described. The present note is a description of a working model of a plant nitrator constructed in connection with a similar project. Most of the dimensions and details of construction are
WORKING
MODELO F PLANT NITRATOR
revealed by the accompanying diagram and photograph, but a few additional suggestions are offered for what they may be worth. Materials and Construction The shell of the nitrator is made of a good grade of cast iron, 7 inches deep and with a mean diameter of about 9 inches. It is supported by a heavy tripod 7l/2 inches in height. For a sleeve we used a steel cylinder 28/r inches in diameter and fastened i t to the bottom of the nitrator by means of '/&nch angle supports. A Sinch propeller with three blades is placed flush with the bottom of the sleeve. Around the sleeve is wound a cooling coil of 3/rinch lead tubing.
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A mixture of spent acids (nitric and sulfuric) is added to the nitrator until the propeller is capable of lifting the mixture over the sleeve. The calculated amount of the material to be nitrated (benzene) is now added and the contents cooled by pumping the mixture over the lead coil. When the mixture bas been cooled to the desired temperature, add slowly from a large separatory funnel the correct amount of fuming sulfuric and nitric acids. The time required for adding the mixed acids will depend upon the speed of the propeller and temperature a t the water in the cooling coil. When the nitration is complete, the contents are allowed to settle for several minutes. By using the valve on the bottom of the nitrator, it is possible to draw off, first, the heavy spent acids and finally the nitrated product. Products such as nitrobenzene should be washed several times with water and finally with a solution of sodium carbonate. The yield, quality of the product, and concentration of the spent acids offer excellent opportunity for the student to make special investigations.
