9 50
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
The standard is most properly the analysts' guide and should be promulgated for t h a t purpose. T o incorporate a standard in the law other than to regulate as we have stated above the minimum strength of the essential ingredient or the maximum amount allowable of any specially undesirable constituent is to place a premium upon analytical incompetency. There are places where the standards can be stated and may be properly incorporated in the law. This includes the fat and solids in milk, but not the ash nor the specific gravity nor the refractive index of the serum. Likewise the acid of vinegar but not the solid, ash, alkalinity, glycerine, nor the other non-valuable constituents. The vanillin content of vanilla extract per-
Vol. 5 , No.
II
haps; the citral content of lemon extract; the arsenic and iead limits in foods and food colors; and the maximum amounts of preservatives, if permitted, may be made a part of the law with perfect propriety. The standard laid down in the law should be the minimum quantity permissible of the desired constituent or the maximum quantity allowable of any undesirable ingredient, and for purposes of food law enforcement, it will be found, we think, preferable to limit the standards, in so far as they are read into the law, to practically these two conditions. DETROIT TESTIXG LABORATORY DETROIT, MICHIGAN
CURRENT INDUSTRIAL NEWS B Y W. A. HAMOR
AN AUTOMATIC CHEMICAL FEEDER According to Engineering Record, 68, No. I O , 264, a n automatic type of chemical feeder has recently been tested a t the hydraulic laboratory of the University of Illinois by the patentee, Ralph Hilscher. The apparatus works in conjunction with a Venturi meter and depends for its action directly on the decreased static head a t the restricted section. Referring to the sketch, the device consists of a box divided into two compartments by a wall which extends from the bottom Y to within a short distance of the top. At the top of this wall is pivoted a horizontal arm, from which are suspended two floats of equal dimensions, one in each compartment, and a t equal distances from the pivot. The arm in compartment B extends beyond the float and connects with a balanced valve on the end of a feed pipe, which supplies chemical from a supply tank. The valve is so made t h a t when Dmgram of Chemical Feeder the float in B falls below the float in A the downward movement of the arm will cause the valve t o open and admit chemical solution to compartment B. Connecting compartment B with the reduced section of a Venturi tube is a pipe in which there is an adjustable valve. Another pipe connects A with the full section of the Venturi tube. The Venturi tube is inserted in the pipe to which i t is desired to feed the chemical. When a flow of water occurs through the Venturi tube unequal pressures a t the full and reduced sections will tend t o make the levels in A and B different, that in B being lower. This difference in pressure, represented by 12, is proportional to the square of the rate of flow through the Venturi tube and, if utilized to force chemical solution through a n orifice, will produce a flow through t h a t orifice directly proportional to the flow in the main. The adjustable valve acts as a n orifice in this device and the desired effective head on i t is established by building up the level in B equal t o that in A. As already explained, these two levels are kept the same by the float arrangement. Referring t o the test sheet, the figures are for four different tests, each with a different size of opening of the adjustable valve. The first column contains the quantities of water treated, measured in a large tank at the end of each run. Column z contains the corresponding quantities of solution fed by the machine, determined by measuring the drop in the supply tank. Column 3 gives ratios of Column 2 t o I , and these figures should all be the same theoretically for a given size of orifice. The ratios are averaged for each test, and in the sixth column are
TSSTSO F AUTOMATICC H E M I C A L FEFDBR 0 n-e I e +
4
c
I
.
Average, . . . 1620 5.85 1014 3.80
0
a
g
. . ..
Average. . 1365 3.55 1506 3.58 1653 4.07 Average..
.. . .
a e
.E
e
E E P
I.
25
?&
m
.i! : :
h% ? P
W
- 0 %
$ 2 F. u l d o
c c r
0
i
5.39 6.30 5.12 10.11 17.10
113 112 131 146 80
+6.2 +3.2 -5.8 -7.7 +4.3
202 277 267
9.20 18.55
174 54
+1.8 -1.8
434 426 445
19.30 10.00 14.30
66 168 93
-0.2 -2.1 $2.3
435 384 420 407
13.30 26.00 10.00
101 58 165
4 . 8 4-4.0
. . . . . . 272
Average. . . . 1294 2.98 1680 3.94 1355 3.04
z4
'i gz
A
214 208 190 186 210
,.
'5
.-e m
2.98 3.49 3.58 8.03 6.59
f
E'@
s 639 726 682 1495 1382
'-
N
-
-
4-0.8
404
given the per cents by which the various ratios depart from the average. B y reference to the fifth column it will be seen t h a t rates a t which water was treated varied by about 300 per cent.
YICARTA AND BAKELITE MICARTA Micarta is a new material which has been developed by the Westinghouse Electric and Manufacturing Company, East Pittsburgh, Pa., to take the place of hard fiber, glass, porcelain, hard rubber, built-up mica, pressboard, rawhide, moulded compounds, etc. ; it is used for commutator bushings, brush-holder insulation, as noiseless gear blanks, as conduit for automobile wiring, as spools for spark coil and magnet windings, for refillable fuse tubes, for wireless coil separators, for arc shields in circuit breakers, for water-meter discs, etc. Micarta is a tan-brown colored, hard, homogeneous material having a mechanical strength about 50 per cent greater than hard fiber. It can readily be sawed, milled, turned, tapped, threaded, etc., if a sharp pointed tool is used, and the work done on a lathe. It can be punched only in thin sheets and cannot be moulded. Micarta is not brittle, and will not warp, expand, nor shrink with age or exposure to the weather, but takes a high polish, presenting a finished appearance. Two grades of the material are made. The grade known as bakelite micarta will stand a temperature of 150' C. continuously, or 260' C. for a short time. It is infusible and will remain unaffected by heat until a temperature sufficient t o carbonize
