NOTES A N D CORRESPONDENCE.
813
condition that red lead (or- lead dioxide) does not completely oxidize i t , and therefore what is left of the carbon after the boiling with this reagent reduces the permanganic acid to a certain extent, so t h a t repeated results, although agreeing with each other, are too low. The obvious remedy for this is to get rid of the carbon first. The writer thereIO0 I = I O 0 x - = 1.54. fore finds i t convenient to use the filtrate from the silicon Specific Gravity = 2 6 2 - 197 65 determination for the manganese determination, a s folAfter making a determination the flask is emptied and lows: 2.3510 grams steel are dissolved in jo cc. water and rinsed, then allowed to drain for one minute, when another IO cc. strong sulphuric acid and evaporated to dense fumes. determination may be made. Then boiled up with water and filtered into a n Erlenmeyer This method is very rapid and so simple t h a t an inex- flask marked a t zoo cc., and the silica washed twice with perienced operator can without difficulty make over 80 water. The'filtrate is then diluted t o the mark, mixed, determinations per day accurate to within 0 . 0 2 unit of 2 j cc. withdrawn with a pipette, and transferred to a tall specific gravity. It is, of course, self-evident t h a t this narrow IOO cc. beaker marked a t 5 0 cc. Then diluted up method has a wide range of applicability; the gravities of to this mark roughly with 1.20 nitric acid, boiled I j minutes, such materials as rocks, drillings, etc., may be determined removed from the heat and the red lead a t once added and with ease. stirred, then diluted carefully to the mark, and stirred While the authors claim nothing new or radical in this again. The lead sulphate formed settles instantly and process, still they submit i t a s a procedure by which results carries with i t the excess lead oxide, so that the comparison of moderate accuracy can be obtained with great rapidity, of the color with a standard steel which has gone through while the outlay for special apparatus is practically nil. the same process can be made a t once (and the quicker the ABRAHAM G. BLAKELEY. better) by withdrawing j cc. with a pipette and transEDWIN11. CHANCE. ferring to ordinary color carbon comparison tubes. The LABORATORY OF THE following results on basic open-hearth steels illustrate this P. & R. COAL& IRON CO., source of error. POTTSVILLE, PA.
No calculation a t all need be made if a table of reciprocals be available, a s specific gravity = IOO X reciprocal of Vo-V,. As a n example IOO grams coal were taken; volume of flask, Vo = 262 cc.; volume of water added to coal, VI = 197 CC.
LIQUID MIXTURES FOR MAXIMUM AND MINIMUM THERMOMETERS. A homogeneous liquid mixture may, by a change of temperature or by certain additions, become separated into two layers. For example, a mixture of I j cc. amyl alcohol, 2 0 cc. ethyl alcohol, and 32.9 cc. mater is homogeneous above zoo C.; b u t the least lowering of temperature below this, even by one-tenth of one degree, causes the division of the liquid into two nearly equal layers. This phenomenon can be made use of in the construction of an exceedingly delicate minimum thermometer. Convenient volumes of amyl and ethyl alcohols are mixed together, brought to the required temperature, and water gradually added, drop by drop, until a slight turbidity results. The liquia is then sealed in a tube, being first colored with carmine whenever the temperature falls below t h a t at which it was prepared, the two layers separate, and are of different shades, If methyl and ethyl alcohols be used in the same way a maximum thermometer can be prepared. ROBT. E. BR4DLEY. THE RAPID DETERMINATION OF MANGANESE I N STEEL. All methods whether color or volumetric, dependent on the oxidation to permanganic acid by red lead or lead dioxide, suffer from the disadvantage of organic matter in these reagents which reduces the Mn,@, after i t is formed. Still it is possible to get red lead t h a t serves the purpose, provided a sharp look-out is kept for splints of wood in the liquid after the boiling, and the test is repeated, or done in duplicate with a fresh portion of the standard, B u t in addition there is a source of error from the carbon in certain these steels are steels. I t seems that in certain steels-but the exception and not the rule-the carbon is in such a
Per cent. No. 15072 b y Williams' method (at another works). . . . . . about 0 . 3 9 No. 15072 b y ordinary color method.. , . , . . . . , , 0.315-0.345 No. 15072 by modified color as above. . . . . . . . . , , , 0.39 No. 15072 b y Volhard's method. . . , , . . . , , ,.. 0.39 No. 15082 b y Williams' method (at another works). . . . . . about 0 , 5 7 No. 15082 b y ordinary color method. . . . . . 0.435-0.455-0.415-0.435 No. 15082 b y modified color as above.. . . . , , . 0.555 No. 15082 b y Volhard's method.. . . , , , , , . . .. 0.57 The color tests b y Mr. A. Kabline.
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GEORGEAUCHY.
A MODIFIED KJELDAHL CONNECTING BULB.
EDITOROF
THE JOURNAL O F INDL-STRIAL .4ND
ENGINEERING
CHERIISTRY: DEAR SIR: In your October issue, page 7 3 7 , there was described a modified Kjeldahl Connecting Bulb; the modification will be useful. I would, however, call attention to another modified form which I designed and have had in use for some time in my laboratory, and is now being used by many other chemists in England. It consists of a large bulb A, somewhat pear-shaped about 7 cm. in diameter, inside which, to the outlet from the large bulb, is attached a smaller bulb, B, about z cm. i n diameter with a hole about 8 mm. diameter blown in the side and an opening about 2 mm. diameter a t the bottom. At the lower part of the large bulb is fixed a thin glass plate C perforated with about six holes; the holes are toxards the sides of the plate a s far as possible from the centre. This form of bulb has a wide application and especially in the estimation of volatile fatty ' ' acids in butter and butter substitutes, ammonia, arsenic and antimony by the distillation method, for the distillation of tar and tar oils and gen-
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