April, 1923
I N D UXTRIAL AND ENGINEERING CHEMISTRY
The physical properties of the lime, such as apparent density and size of particles, influence the free-settling rate-the more granular and compact the particles, the greater the settling rate. In the plant economics of causticieation, three problems frequently arise, namely: I-With a given equipment, what are the best operating conditions to yield a product of definite amount and concentra tion? 2-With a given equipment, what are the best operating conditions for maximum production?
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3-Por the design of a new plant what operating conditions should be chosen? The first two problems are of immediate importance, because a plant manager always desires to know how to operate his plant a t minimum cost and again how to obtain increased production without expending a “cent” for additional equipment. In all three problems, the final operating conditions are chosen after making an economic balance on the factors involved, such as cost data, time of causticization, and amount and character of the lime. This latter information can be obtained from runs made on the given lime, similar to thwe presented in this paper.
Detection of Sugar in Condensed Waters by Means of Cresol’ By G. E. Stevens THEGREATWESTERNSUGARCo., EATON,COLO.
URING the war several substitutes for alpha-naphthol as a reagent for the detecting of sugar in condensed waters were experimented with, but no satisfactory reagent was found that would give satisfactory results. The research had to do largely with the higher phenols, such as resorcinol, etc. It occurred to the writer that the lower phenols, such as creosote, cresol, etc., had possibilities. ,410ng with finding a suitable substitute was a desire to find also a cheap solvent which would eliminate the use of alcohol. With these ends in view several phenols mere experimented with, and after various comparisons and experiments cresol was found to give satisfactory results. The chief difficulty was in finding a solvent that in no wise hindered or affected the color reaction and a t the same time was a good solvent. Cresol has a solubility of only 0.3 in water; therefore, if water was to be used as a solvent or vehicle, some substance soluble in water and at the same time a solvent of cresol must be found. Castile soap was found to be a good solvent for cresol in the proportions of 6 g. of soap to 15 cc. of cresol, the soap previously being dissolved in 100 cc. of distilled water. This solution can be made up in liter quantities without apparent deterioration. If solution is not effected on warming and agitation, the addition of a little more soap will complete the solution. One objection to the use of a-naphthol has been that in most cases &naphthol is usually prfsent to some extent, which produces a green coloration on the addition of concentrated sulfuric acid, Iron and lime salts also produce various colorations which, if present in sufficient quantities, tend to mask the violet ring, especially in the detection of traces of sugar. By the use of the cresol solution the foreign color reactions are almost entirely eliminated and a decided color ring is obtained only in the p’resence of sugar. A solution containing 1 part sugar in 100,000 parts of water, and also a trace of oil, lime salts, iron (held in solution by means of ammonium oxalate), ammonia, and other mineral salts was tested, and the color reaction found to be unaffected to any extent with no foieign colors present sufficiently to mask the test. The castile soap in the presence of lime salts really acts as an aid, a3 the milky color produced serves as a good background in making the color reaction more prominent. PROCEDURE Put about an inch of the water to be examined in a 6 x 5 / ~in. test tube (a 6 x 1 in. test tube is recommended in detecting
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Presented before t h e Dlvislon of Sugar Chemistry a t the 64th Meeting of the American Chemical Society, Pittsburgh, Pa., September 4 t o 8, 1922. 1
light traces) and add 5 to 10 drops of the cresol solution and contents thoroughly mixed. Cool the contents if warm and then add concentrated sulfuric acid from a dispensing buret, holding the tube in an inclined position so that the acid will run to the bottom and form a separate layer, and continue to add the acid until the acid layer is ‘/z to 3/4 in. deep. Then roll the tube between the hands and if sugar is present a reddish black to pink color ring will appear, the color depending upon the concentration of the sugar. It is recommended that white translucent screen be placed between the eye and the source of light, as this aids in recognizing more easily the color reaction, especially in faint traces. ADVANTAGES This solution can be cheaply prepared, the cost for a 100-day campaign would be approximately $1$00. It eliminates highpriced solvents, and is very sensitive, giving a color reaction on standing a half-hour of 1 part sugar in 500,000 to 1,000,000 parts of water. There are no serious foreign color reactions to interfere or mask the test, and the color rings are of such a nature that a rough estimate of parts of sugar present can be estimated. While this method has not been tried out during plant operations, various waters were tested and the writer believes it to be applicable in all respects and to serve the purpose as a possible substitute forthe a-naphthol method. The accompanying color chart shows the color reactions of various parts of sugar present in solution. This chart represents merely the colors observed by the writer while making the various tests, and to other individuals the color mould probably seem slightly different. COLOR REACTIONS WIITH KNOWN P A R T S Of SUGAR I N SOLUTIOh Parts Sugar in Solution COLORRBACTION 1100 Reddish black turning t o black 1500 Reddish brown t o black 11,000 Reddish brown 16,000 Deep red t o reddish brown 1 10,000 Red t o dark red 1 20,000 1,ight red t o deep red 140,000 Pink t o light red 60,000 Pink t o light red 1 180,000 Light t o heavy pink 1 100,000 Pink 1 180,000 Light pink in few sec. 1 200,000 Light pink in 20 sec. 1 250,000 Light pink in 30 sec. Light pink in 1 t o 2 min. 1 - 300,000 1 350,000 Light pink in 5 min. 1 - 400,000 Light pink i n 18 min. Light pink i n 1 t o 2 hrs. 1 1,000,000
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NOTE: Slight agitation of the contents of t h e tube hastens reaction in light traces. A very light brown color is t o be disregarded a n d will disappear upon agitation, and a pink color develop, if sugar is present.
