PRESSURE REGULATORS
Pressure regulators of the type used by P r e g l1 1 2'1 1 3'2 8 4'2 8 5-3 0 8'3 1 7-3 2 0'3 5 0 and for which specifications have been recommended by the Committee for the Standard
ization of Microchemical Apparatus of the American Chemical Society3 5 1 may be used in place of the ones described. Figure 132 shows the glass parts of this regulator, unassembled. Two are required when air and oxygen are used as described under Procedure. The cylinder on the right is filled with 5 % sodium hydroxide and the center piece, held by a metal clamp which is not shown in the drawing, Fig. 132, provides for the pressure head in much the same manner as the regulator shown in Figs. 118 and 119. The three-way stopcock is used to connect the air and oxygen regulators to the bubble counter-U-tube.
Oxygen alone may be used for the determination. For such a setup, one pressure regulator is used. The absorption tubes may be weighed, filled with oxygen, or it may be replaced by air employing an aspirator.2 8 4-2 8 5 I f the oxygen
GLAZEΟ 30-35 MM.
L_LL _
12 MM. DIA. PLUG AT CENTER X 5to.5MM.QD" 1-2 MM.I.D. 50-52.MM.I
40-45 5tQ5 MM.O.D.^-MM' GLAZED WALL I MM APPROX-r 30-35MM|
1
R^5*0,5MM. O.D. 1-2 MM. I,D. GLAZED [_70T 3 MM. 70Î3MM. I. . 3 WAY STOPCOCK 1,5 MM. BORE DIMENSIONS SAME AS FOR $ H/2 STOPCOCK (EXCEPT BORES) I REQUIRED25-30 MM. GLAZED
.| ^ ι 15-20 MM. ~K ,Vp^40-45 210-220 MM. 5 MM. APPROX,
GLAZED Τ 120-30 I MM, GLAZED 510.5 MM.0.D. WALL I MM. APPROX. 210-220 MM) ^_20-25 MM, QD. WALL 1.25 MM. APPROX. Ί
iff
1 ^GLAZED 2 REQUIRED 45-50 μ-ΜΜ.ΟΌ. WALL 2-3 MM. 2 REQUIRED FIG. 132. Glass parts for pressure regulator—details of construction.257 Additional Information for Chapter 9
is not replaced, the tubes must be rapidly weighed or a special type of absorp
tion tube used—see below.
PREHEATERS
Preheaters of the type shown in Fig. 133 have been u s e d4 1'1 1 2'1 1 3-2 8 4'2 8 5 , 3 1 7"
32θ,3δο,3δΐ |-0 pu ri f y the air and oxygen if traces of hydrogen from electrolytic oxygen or particles of dust from the inside of the rubber tubing are present.
COMBUSTION TUBE ^
C
6 0 6 5 M M
-4 MM. ±0.5 O.D.
U — W A L L I M Mi.
1 (APPROX.)
5 Î 0 . 5 MM. O.D.
WALL I M M . APPROX. *
JOINT
SOLID ROD BRIDGE 8 0 - 8 5 M M .
100-110 M M .
9 0 - 9 5 MM.
3 GLAZED 5 Î 0 . 5 M M . O.D.
WALL I M M APPROX.
125-135 MM.
110-120 M M .
L-30-40MM.-J
FIG. 133. Preheater—details of construction.
It consists of a section of combustion tube containing copper oxide and heated to about 600° C. The oxygen or air enters from the pressure regulator on the left, passes through the hot copper oxide, then down through the cooling spiral and into the bubble counter-U-tube. With the use of a preheater, an extra drying tube is used between it and the pressure regulator. The author does not recommend the use of preheaters and his opinion is shared by others.3 8 2
HEATING MORTARS
P r e g l3 0 8 first used a copper block as a heating mortar and later used a hollow unit containing either a petroleum fraction boiling between 190° and 220° C.
or />-cymene, boiling at 176° C. The unit was heated by means of a small gas flame and the liquid kept at its boiling point. Specifications for an all-glass unit of this type have been recommended by the Committee for the Standardization of Microchemical Apparatus of the American Chemical
SO-G L A Z E D
3 8 0 - 4 0 0 M M .
r
- 1 6 - 1 8 M M . O.D.W A L L I . 2 5 - I . 5 0 M M .
Η 7 0 - 7 5 M M . H FIG. 134. Heating mortar—details of construction.
c i e t y3 5 0'3 5 1 which is shown in Fig. 134. It is filled with p-cymene and heated by either electricity or gas.
ABSORPTION TUBES
Pyrex tubes have been used by MacNevin and V a r n e r .2 5 2 They did not wipe them and, in addition, used an absorption tube as a tare. Control absorp
tion tubes have also been used by Friedrich.9 7 The a u t h o r3 4 9'3 5 0 does not recom
mend the use of Pyrex tubes because they easily become charged with static
259 Additional Information for Chapter 9
electricity and often require almost an hour to dissipate their charges even after grounding2 8 5 and exposure to ultraviolet l i g h t ,2 8 5'3 1 6 pitchblende,1 2 0-2 8 5
* 'spent radium tubes" (capsules containing inorganic salts exposed to emana
tions and previously used for treatment of c a n c e r ) ,1 2 0'2 8 5 or, on occasion, the spark of a high-frequency c o i l .2 8 5'3 6 9
GENERAL
For obvious reasons, the determination of carbon and hydrogen should be considered to be the most important of all the determinations on organic compounds and the large number of articles appearing on the subject sub
stantiate this idea, there always being hopes of improving the method. It has been emphasized that the procedures presented in the preceding pages have proven reliable over the years. There are, however, a number of very reliable procedures which have been developed in recent years and which are being used extensively. The "empty-tube" methods developed by Belcher, Ingram, and S p o o n e r2 7'3 4'1 4 8 are being used in the United Kingdom to a greater extent than elsewhere. These use a quartz tube containing baffles and a small amount of silver. The temperatures employed are higher than usual, the tube is held vertically, and high rates of flow of oxygen are used. The so-called Kôrbl f i l l i n g s1 9 6-2 0 2 are rapidly gaining favor throughout the world. The most com
mon consists of the decomposition products of silver permanganate. The filling is usually shorter than normal and the temperature lower. Kôrbl's studies have included other oxides. The simultaneous determinations of several elements have obvious great value as does the extremely important submicro- or micro
gram procedures developed by Unterzaucher3 6 3"3 6 5 and by K i r s t e n1 7 6'1 7 7 in Sweden. As this book goes to press, an automatic apparatus has become com
mercially available.6 1 a Its construction and appearance are very similar to that of the nitrogen analyzer (Fig. 104, Chapter 7 ) except that in place of the nitrometer and counter there are various absorption tubes. On trial in the author's laboratory, good results were obtained on a number of compounds.
For additional material in regard to the subject matter of this chapter, the reader is referred to Table 20.
T A B L E 20
ADDITIONAL INFORMATION ON R E F E R E N C E S * RELATED TO C H A P T E R 9
As in the case of previous chapters, the author presents in the form of Table 20 the additional information which he wishes to call to the attention of the reader. (See state
ment at top of Table 4 of Chapter 1, regarding completeness of this material.) Books
Ogg, Willits, Ricciuti, and Connelly, 294 Pepkowitz, 299
Pickhardt, Safranski, and Mitchell, 303 Schôniger, 336
Statistical studies Fieser and Jackson, 85
Ogg, Willits, Ricciuti, and Connelly, 294 Power, 305
* The numbers which appear after each entry in this table refer to the literature citations in the reference list at the end of the chapter.
261 Table of References
Role of lead dioxide, omission of lead dioxide, substitutes, etc.
Abramson, 2
Abramson and Brochet, 3 Baxter and Hale, 21 Belcher and Phillips, 31
T A B L E 20 (Continued) Role of lead dioxide, omission of lead
dioxide, substitutes, etc. (Conf.)
Mizukami, Ieki, and Morita, 274, 275 Niederl and Niederl, 284, 285
La Force, Ketchum, and Ballard, 221 Lysyj and Zarembo, 248
Freier, Nippoldt, Olson, and Weiblen, 92 Gel'man and Korshun, 108
Rush, Cruikshank, and Rhodes, 325, 326 Schwartzkopf, 338
263 Table of References Mizukami, Ieki, and Morita, 274, 275 Niederl and Niederl, 286
Van Slyke, Folch and Plazin, 368
T A B L E 20 (Continued)
Freier, Nippoldt, Olson, and Weiblen, 92 Fujimoto, Utsui, and Ose, 99 Korshun, Gel'man, and Glazova, 204, 205 Korshun, Gel'man, and Sheveleva, 206
Belcher, Thompson, and West, 35, 36 Delaby, Damiens, and Tsatsas, 71
265 References
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