The Chemical Control of Ammonia Oxidation
Journal of Industrial & Engineering Chemistry
of t h e work done b y X-light, using a t u b e of unit dimension, P being t h e penetration as measured on a Wehnelt penetrometer. Using a slide rule covering t h e equation D Z T Z x = -> c PZ D = distance in inches between target and glass T = thickness of glass C = current measured in milliamperes P = Wehnelt penetrometer readings X = exposure in seconds we have a formula based upon a hypothetical unit of light which one can vary t o produce with exactness a n y desired result. Each make of
... esult. Each make of glass, of course, has its own rate of speed of change by which t h e r a l u e X must be multiplied. The coloring of purple glass is undoubtedly due t o manganese, yet t h e color of this glass is not exactly t h e same as in t h e manganese specimens, which have been tested. This, of course, can possibly be accounted for in several ways, such as t h e difference in t h e chemical substance of t h e glasses, or due t o t h e oxidation of t h e manganese, which may be different as obtained b y radiant energy t h a n b y t h e regular glass manufacturing process. T h e other colors obtainable, very likely follow along t h e same lines, b u t i t is also hard t o believe t h a t anything else b u t a direct physical change in t h e material, or a direct molecular rearrangement has taken place. Considering t h a t b y t h e application of heat, molecules can be rearranged, t h e action would appear, if taken synthetically, more naturally physical t h a n chemical. S Z; M MA R P I-White glass turns t o different colors under this method. 11-Knowing t h e composition of t h e white glass, t h e color can be predetermined. 111-The depth of coloring of t h e glass is dependent on penetration of t h e rays, h e w e controllable. IV-The action is molecular a n d not confined t o t h e surface of t h e glass and t h e color is in and through t h e glass itself. Y-The action is reversible. VI-In coloring glass by t h e above-described method, results can be obtained which are not possible with glass colored by chemicals. VII-Other analogous substances, such as porcelain, quartz, and some of t h e precious and semi-precious stones, particularly those colored by manganese, respond t o this method of treatment. The writer of this article makes no pretense t o accurate scientific knowledge, b u t gives t h e results of his observations and methodical experiments with t h e well-known phenomenon in t h e hope t h a t they may add some mite t o t h e s u m of human knowledge and may stimulate those who are better versed in scientific studies t o ascertain t h e exact cause and operations of this interesting power of t h e short wave lengths of light. . ROSENTAAL I n t h e oxidation of ammonia t o produce nitrous or nitric acid, t h e ammonia, mixed with air, is passed over a catalyzer heated t o a red heat. The ammonia content t o t h e air-ammonia mixture is given either b y running t h e air through aqueous ammonia or by mixing t h e ammonia gas with air. When t h e ammonia content is obtained by passing t h e air through aqueous ammonia, t h e mixture, of course, is saturated with water vapor a t t h e given temperature. I n t h e operation of this process, either on a n experimental or manufacturing scale, one of t h e most pressing problems is t h e chemical control, for on i t depends t h e accurate adjustment of t h e factors necessary t o t h e efficiency of t h e plant. I n fact in starting a new commercial unit, or getting d a t a on a design of furnace, or merely in testing a new catalyzer, especially over any period of time, t h e principal practical issue is finding out exactly what t h e chemical performace is under the various conditions (temperature and character of catalyzer, speed and composition of ammonia-air mixture, etc.). The chemical control naturally falls into four parts: ( I ) t h e examination of t h e gas before passing to t h e catalyzer, and (Z:I after coming from t h e catalyzer, (3) t h e working up of t h e results, and (4) t h e determination of nitrous acid. For t h e determination of t h e fairly high content' of ammonia in t h e entering gas, t h e ordinary gas analysis methods with mercury as confining liquid are applicable or t h e ammonia may be absorbed in standard acid and titrated. -4 thorough discussion of t h e various absorbing arrangements will be found in a paper by Edwards2 on t h e absorption of ammonia in illuminating gas. The method by absorbing in standard acid has t h e advantage t h a t a much larger sample can be used-in fact a continuous sample can be taken-and t h a t no mercury is required. T o test t h e Cumming absorber, t h e writer ran 1000 cc,of I O per cent ammoniagas through one like t h a t figured by Edwards, another absorber being connected in series beyond it. S o t a trace of ammonia passed into t h e second absorber, showing t h a t one is sufficient t o collect all t h e ammonia. It has occurred t o t h e writer that with this type of absorber it is possible t o determine t h e ammonia without making any titration. This is done by putting in a measured quantity of standard acid, coloring with an indicator and bubbling through t h e ammoniaair mixture, until t h e color turns. If t h e gas has been collected in an aspirating bottle, t h e volume corresponding t o t h e quantity of standard acid used is known, a n d the per cent of ammonia in t h e original mixture can be easily computed. T h e reason why this is possible is t h a t in t h e Cumming absorber there is a fair circulation, and with a little practice i t is not difficult t o hit t h e turning point, as t h e liquid is always approximately of t h e same composition. At t h e same time, t h e appearance serves warning as t o when t h e change will occur.