T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY absorption with only one absorber, but possibly the absorber K “ is better than his. The use of a manometer is not very convenient. The same criticism applies to the evacuated bottle method as described. A sufficiency of oxygen is not assured, except under special conditions. Moreover, a pump capable of evacuating to 2 mm. is necessary as well as connections and capillary stopcocks so well ground that they will retain the vacuum mentioned. Fortunately a concession is made in the matter of ground glass connections. What all these mean, it is unnecessary to state. The statement that it is the only method permitting the determination of ammonia escaping oxidation presumably applies only to the procedures described in the paper, for it is perfectly feasible by our method. We are convinced that anyone trying the vacuum bottle method will find it exceedingly elaborate. Presumably the plan could be modified by adding a measured amount of oxygen first to the vacuum bottle, but it then becomes even more complicated. A larger bottle will also be required to cover all cases of gas mixture. Messrs. Taylor and Davis present a method for eliminating titrations because “the principle involved offers possibilities for development of a rapid method of works control.” The essential novelty of the principle however-the running of a gas into a definite volume of liquid stained by an indicator until the indicator turns-had been stated already by the present writer in the second and third paragraphs of his paper. They have added an elaborated glass apparatus which would impress us as being a great deal more troublesome than half a dozen titrations. Finally, and this a crucial point, catalyzers do not work uniformly and the taking of a sample should extend over considerable time, in fact should be continuous. It seems to the present writer that his is the only process which has this advantage; i t is also free from limitations on the composition of the gases. He hopes to publish shortly an account of an improved and more compact form of his apparatus, together with a new method of approximate factory control requiring less skill than any of the proposed methods. PAULJ. Pox 1605 E. CAPITOL STREET WASHINOTON, D. C. December 11, 1917
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Editor of the Journal of Industrial and Engineering Chemistry: I n reply to criticisms of Mr. Paul J. Fox, on our paper “Analytical Control of the Ammonia Oxidation Process.” In regard to the oxidation of ammonia by hydrogen peroxide in alkaline solutions, we are convinced that no such oxidation occurs in any method used by us and would not occur in the method proposed by Mr. Fox, even if hydrogen peroxide were contained in his first absorption vessel. No experimental evidence of such oxidation is presented by Mr. Fox, and certainly none in the reference quoted by him.’ However, the question is relatively unimportant since little or no ammonia is allowed to pass the oxidizer in commercial operation. In regard to the second point at issue, the completeness of the oxidation of NO to NOS, the literature cited by us and confirmed by our own experiments shows that this reaction is not a n instantaneous one and has a negative temperature coefficient. The latter is important. If the gas is not cooled to room temperature even with a large excess of oxygen, there is no assurance that the reaction will complete itself unless a large reaction space is provided before the gases enter the alkaline absorbing solution. The apparatus sketched by Mr. Fox shows that the only reaction space provided is the narrow tube conducting the gases to the bottom of the absorption vessel. Since the gases must be kept hot till they enter this tube to prevent moisture condensation, it appears likely to us that the reaction does not complete 1
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itself before the acid oxides are absorbed by the alkali. But if Mr. Fox obtained practically equal quantities of nitrate and nitrite in his absorbers from the hot oxidizer gases, we withdraw the objection in our original paper. We quite agree that NO is not absorbed by alkali or alkali containing hydrogen peroxide. But a mixture of NOz and NO in any proportions such that NO does not exceed that of NOz is more readily absorbed by alkali than NO2 alone.’ I n our aspiration method a partial reaction of NO to NO% was all that was required. The use of oxygen was to clear absorption vessel K ” of air at the beginning of the test and of the oxidizer gases a t the end of the test and not to assist in the absorption as assumed by Mr. Fox. In our opinion no aspiration method is very satisfactory. We do not agree that it is desirable to draw continuous samples, or samples over a period of time. I n fact, to the authors’ knowledge, a commercial plant using an aspiration method similar to that advocated by Mr. Fox, has recently discarded i t in favor of the vacuum method which they have recommended. The vacuum bottle method has been in use over a year under all‘ kinds of experimental conditions and in actual plant operation, where i t has proved satisfactory. When high concentrations of ammonia are being oxidized it is necessary to introduce a little pure oxygen after taking the sample, but it is not necessary to measure i t and is 60 trouble whatever. One man with a little experience can make a complete efficiency test including calculation of results in half an hour if determination of the free ammonia escaping oxidation be neglected. BUREAU OF MINES G w B. TAYLOR WASHINGTON, D. C. J. D. DAVIS January 3, 1918
AVOIDABLE WASTE IN THE PRODUCTION OF SULFURIC ACID BY THE CHAMBER PROCESS Editor of the Journal of Industrial and Engineering Chemistry: I n connection with the subject of the increased production of sulfuric acid called for on account of explosives requirements, it is interesting to consider one phase which seems to have escaped general observation. In the United States we make some four million tons of acid by the chamber process each year. Very few chamber plants are run on a scientific basis; in fact, most of them operate by rule of thumb, this being particularly true of the acid plants attaehed to fertilizer factories. While there has never been a survey made of the average operating conditions in the chamber plant acid industry, I am reasonably sure from the data I have gathered during the past five years that the average chamber plant space obtained by combining all the plants in the country would be of the order of 1 3 cu. f t . per pound of sulfur burned. With proper analytical control of the gases, and with exact control of the volume and temperature of the acid circulated over the towers there is no reason why the chamber space used should not be cut down to I I f t . per pound OF sulfur burned per 24 hours. Suppose, however, the average improvement is no more than a reduction to 1 2 cu. ft., we would have an increased output. without the construction of additional plant, of some 300,000 tons of 50’ Be. sulfuric acid per year. A questionnaire sent to the acid manufacturers covering chamber acid output and chamber space per pound of sulfur, would soon show the possibilities of increasing our acid production in the way I have indicated, but, of course, such a query to result in answers of real value would have to be sent out b y some department of the Government. A. E. MARSHALL BALTIMORE, MD. Chemical Engineer January 4, 19 18
