INDUSTRIAL AND ENGINEERING CHEMISTRY
620
through a Gooch crucible, wash with hot water, and dry a t
looo c.
DETERMINATION OF BROMATE-Dissolve 2 grams of chlorate in 100 ml. of water (preferably air-free) in a 250-ml. Erlenmeyer flask. Add 5 ml. of 1N hydrochloric acid (l:lO), 5 ml. of 10 per cent potassium iodide solution, and 5 ml. of 0.5 per cent starch indicator. Prepare an identical blank analysis, omitting the chlorate. Stopper the flasks, keep them an hour in a dark place, and titrate the liberated iodine with 0.02 N thiosulfate.
Vol. 16, No. 6
3-An iodometric method for determination of small amounts of bromate in potassium chlorate has been investigated and found to be reliable.
Direct Reading Apparatus for Determining the Approximate Specific Gravity of Solids‘ By E. A. Vuilleumier
1 ml. 0.02 N NazSzOs = 0.000557 gram KBrOs
TESTS OF METHOD FOR DETERMINATION OFBROMATE INKC~O~ DICKINSON COLLEGE, CARLISLE, PA. The procedure given is a modification of the method of HE hydrometer is so convenient for determining the Kratchmer,ll intended to show quantitatively as little as specific gravity of liauids that it has seemed desirable t o 0.01 per cent of bromate in chlorate. It depends upon a attempt to devise”a comparable in7 proper concentration of reagents for oxidation of hydriodic strument for the determination of acid by bromic acid but not by chloric acid. For obvious the specific gravity of solids. The reasons some doubt was felt as to the reliability of the method, result is the simple, rugged, directand as the first six specimens examined were shown to contain reading apparatus shown in the about 0.1 per cent of bromate, it was suspected that this illustration. might represent the normal action of chloric acid upon The cylinder is filled with water to hydriodic acid under the conditions imposed, even in absence the zero mark, and 100 grams of the of bromate. Two samples were finally obtained, however, solid under investigation are added. which showed only 0.004 and 0.005 per cent bromate, so that The instrument is so graduated that any positive error due to action of chloric acid does not exceed the resulting level of the water gives these negligible values. the specific gravity directly. Up to To determine the actual accuracy of the method, trials the zero mark the cylinder contains were made thus: about 100 ml. The volumes above (1) Portions of a standard potassium bromate solution, con- the zero mark corresponding to the taining 0.00012 gram (0.000118) per ml., were analyzed by the various specific gravity readings are method, with the results given in Table VI. given in the table. The apparatus is especially useful TABLE VI-DETERMINATION OP BROMATE KBrOa Taken KBrOa Foundo for determining the specific gravity Grams Grams of minerals, ores, rocks, and metals. 0.00012 0.00012 0.00012 0.00012 For solids soluble in water, kerosene , 0.00012 0.00012 is recommended. 0.00024 0.00024
T
~~
0.00024 0.00024 0.00059 0.00059 0.00059 0.00118 0.00296
Q
0,00025 0.00023 0.00058 0.00060 0.00062 0.00119 0.00297
Values rounded off t o fifth place.
( 2 ) Portions of the standard bromate solution, with the addition of 2 grams of potassium chlorate whose bromate content had been separately determined, were analyzed, with the results shown in Table VII. TABLE VII-DZTSRMINATIONOF BROMATE KBr03 Taken Grams
KBrOs in Added KC103 Grams
Total KBrOs Present Grams
Total KBr03 Found Grams
0.00024 0.00012 0.00024
0.00007 0.00149 0.00149
0.00031 0.00161 0.00173
0.00031 0.00163 0.00172
The data given in Tables VI and VI1 indicate the method for the determination of traces of bromate in chlorate to be trustworthy. CONCLUSIONS 1-The oxidizing value of potassium chlorate may be determined accurately by Bunsen’s iodometric method, using the apparatus and procedure described, which involves distillation of halogen in absence of air. 2-The frequent claim that the distillation method yields low results is not confirmed, nor is the explanation that the loss is due to interaction of halogen and steam. 11 2. anal. Chem., S4, 546 (1885); Gooch and Blake, A m . J . S c i . , [4] 14, 285 (1902); Gooch, “Methods in Analysis,” p. 471. The authorship of this modification is not known to the writer.
1
Specific Gravity
Voliime of 100 Grams M1.
2.0 2.5 3.0 3.6 4.0 4.5 5.0 6.0 7.0 8.0 9.0 10.0
50.0 40.0 33.3 28.6 25.0 22.2 20.0 16.7 14.3 12.5 11.1 10.0
,
Received May 15, 1924.
N e w Dye Standards The Treasury Department has adopted a new list of standards of strength of coal-tar dyes. This list is a revised and enlarged edition of the tentative list issued by the Treasury Department on August 14, 1923, and is in accordance with a proviso of Paragraph 28 of the tariff act, which provides that the specific duty of 7 cents per pound on finished coal-tar dyes shall be applied on the basis of strength of commercial imports prior to July 1, 1914, since pre-war period dyes generally were imported in lower strength than now. The revised list contains 469 standards, covering about 1100 names of dyes, whereas the original list consisted of 212 standards covering 600 names of dyes. New features are Schultz and Color Index numbers, where there are any, or letters indicating the method of application for each dye; a general index; and keys to the class index and the manufacturer’s name. These standards represent approximately ten months’ work by the customs service in cooperation with domestic manufacturers, importers, and coal-tar experts, and are the result of many laboratory tests made in New York. The list was submitted to large importers and domestic manufacturers for comment, criticism, and correction. As a result, some dyes were eliminated where doubt existed; others, where objection did not appear sound, were retained.
