Figure 4-A
ble between crossed Nicols but scarcei~seen with ordinarv linht.
deveiowd from the edges of the s were maenified 70 diameters (8) &nes 8 contams ohotonraohs of Detrolatum from residual
perature above the meltrng low themelting point.
Forms of Crystallizat
In this preliminary stud noted, all of which obvious1
Flsurc 7-A
praGtical operations of iehning. One type istic of residual oils, tdlates The arpta1 made to grow with d
ib
that cliaraeter-
centers of crystallization of various shapes appear (triangular, iounded, pentagonal, etc.), from which fine needles sprout in 7arious directions. These needles, under temperatuie control, grow in length and breadth, producing the interlacing condition peculiar to slack way. This mode of crystalproducts high in wax concentration, the crude and reiined waxes. The such as slack wa crystallization of cracked-was distillate is different in that the needle formation from centers is not so mark&. Another form in vhieh wax crystallizes is the plate, leaflet, or table As previously mentioned, petrolatum max tends to form plateiie crystals, and in the initial stage of the crystallization of slack was a few platehke and massive crystals are always observed. I n the crystallization of one sample of refined was a large number of plates which needle crystals quickly of the opinion that in many ca5
Figure 6-8
Fipure 6-C
Fisure 7 - 8
Floure 7-C
Fl$ure 8-8
Pleure 8-A
formed, they could have been made to become more numerous by better tcmperature-eontrol. Furthermore, the folloving behavior was ohserved in the cooling of several
Fiavre 8-C
Bibliography l-znioziecki. "Paraffinin P ~ ~ 2-pyhnia, weedie-shaped crystais
~z. ongca. ~ I ~
Their I
s,~201; (1ses). . ~ in the R sweat- ~
~
Conclusion
the actual nature of the wases is of consi
of Parrffins in Benzene. Gaioline, Naphtha,
tem or systems, the effect of asphaltic matter, the stud ' of pure paraffin hydroearhons, and the study of waxes i us crude oils.
ship at the Unirersity oi Oklalioma.
iZ-Guiwitsch, "Crystsiliioe Structure of Paraffin Wax," as discussed in "Wisrenschaftliche Gnindlagen der Srdolbrxrheitung." 13-Tychiuin, Pavlovi. Gerrhon. and Malinina, "Structure and Propeiiies of the Psraffiii-Contriinii Petroleum and Mrzoui 01 Grorny," XeJt.
18-Tychiein,
"Structure and Certain Pruwrties of PeraITm PetioXeJIjmm Slonici~oeCko:iojiIio, 5, 820 (1922i.
leiinis end Groziiy Marout;
Effect of Enamels on Colors by Various Stains The production of colored enamelcd x w e is becoming of increasing importance in the enameliiig industry. Enameled advcrtising signs have been ail article of manufacturc for many ?cars, but more recently colored enamels have found extended application for stove parts and metal household and restaurant furniture. Considerable care is required in the preparation of the various desired shades and tints axid much difkulty is encountered in their duplication. This may be due in some cases a t least to composition of the enamel base and to treatmcnt in application. The compositions of the coloring oxides are also of extremc importance, and since very little information is available, the Bureau of Standards drerncd it essential that they be studied. A numher of coloring oxides were developed from trial tests. These Were used ill three typical enamel formulas of varying cornpositions and of the commercial type. Later some of the oxides were atldcd to batches of a series of enamels which were designed to show the effect of sptematie changes in composition of the frit upon the finished color. Some colored enamels were made hy miring the color-producing elements with the raw batch
before meltinE. Other colors were added to the frit a t the mill. before grinding. Some of the inme important results are: I-When additions of colorins material are made eltins they shoitid he very thoroughly mixed with rrw batch io insure uniform results. Y---Siieht variations in tint oi the coloriii~oxides may affect the shade of the resultant enamel and may he corrected by adding more or less of the
&de.
the case be. 3-Calcined alumina may be used as a body oi oxides. but ail eliceor m i l l affect the .nreoivaiion .
medium in the texture of the
~ O S E and
Gnished
upiieatc any oxide the pioceduie and conditions must
?+-The clay addition tr, the miit batch should be reduce4 l e a minimum and compensated far by finer @inding in order m e l i d a m "sammiog" of the aced rurfaee.
I n order t o correlate results of this investigation with plant practice it is planned t o use laboratory-prepared colors in the production of commercial enamels under plantWnditioiis.
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