10 BULLETIN 1390, U. S. DEPARTMENT OF AGRICULTURE 
The analytical data required in the foundation and supplemental | 
affidavits (70) and the methods for making the analyses are indicated | 
in Table 7, which also shows the purity specifications necessary for — 
certification. 
YELLOW O B 
Yellow O B (C,;Hi;N;3), an oil-soluble monazo dye, is made by 
coupling diazotized o-toluidine with @-naphthylamine. As in the 
case of its lower homolog, yellow A B, it is necessary that any un- 
combined intermediates and any decomposition products of the diazo- 
tized base be completely removed from the final product. 
It is an orange powder, which crystallizes from alcohol in orange- 
red plates and melts at 126°C. It is insoluble in water, but dis- 
solves in alcohol to produce an orange-yellow solution, the color of 
which is reddened by hydrochloric acid but not altered by sodium 
hydroxide. It dissolves in concentrated sulphuric acid to form a 
reddish-violet solution, which turns red and produces an orange- 
brown precipitate when diluted with water. It is soluble in carbon 
tetrachloride and also in vegetable oils. | 
Table 8 lists the analytical determinations which musi be reported 
in the foundation and supplemental affidavits (70), together with the 
methods to be used and the impurities tolerated in batches acceptable 
for certification. 
TABLE 8.—Specifications for yellow O B 
Maximum 
Component tolerance | Minimum Method of 
(ratio to pure! tolerance analysis 
coal-tar dye) 
Per cent ml OF Page 
VOUS PUN Gs tector crs Sena ene a Seni RLU ee Re ye ter On| say eee tees 14, 
Sulphatediachis: 33a eee A. a Pee ee See Nije 4 Pe bane Be seem o] 18. 
Veta ITC UALS Meee mee ee oS elects ieee ONT eS ee ee ee Ne INIONG |e a. see ate 19. 
PAT SEINIG ASDA SIO) ge -= Bon ee er See CPU Ee eee oe ee it ©; 00014 )|Se2s2ee= 2-22 22, 23% 
oare-coalstand yeuststs ce _ eee et Blears wird Te os Se ee ee et ene (1) Fee ease ere ee 26. 
Matter insoluble in carbon tetrachloride__..-_...-..-----_-- et a | ASO 27. 
Water extractives: 
(SVD esl tee a pa ed oe Ry ye CS aio Oa SP Pa EDOM Does eee es Dili 
DACGT Cena Syncs te tek eee ee Shay ee ee eee See “OSM | | Sete eee ik 
Meltingepotnts= . 22228225 ea es Ae ree ee lee ane Oe ree 2120 | 28 
1 Although no limit is here defined, a statement of the percentage found by analysis must be incorporated 
in the foundation and supplemental affidavits (70). 
2 Corrected. 
GUINEA GREEN B 
Guinea green B (C3;H,;;N,0,52.Na), a triphenylmethane dye (72), is 
made by condensing benzylethylanilinesulphonic acid with ben- 
zaldehyde, followed by oxidation of the resulting compound and 
conversion into the monosodium salt. It is necessary in manufactur- 
ing this dye to use very pure intermediates, especially benzylethyl- 
anilinesulphonic acid, which should be as free as possible from 
homologs. This dye is subject to contamination by organic matter, 
owing to side reactions, which may produce benzoic acid and con- 
densation products other than guinea green B. For this reason its 
manufacture requires very careful supervision. 
Guinea green B is a dull dark-green powder or bright crystalline 
solid. It dissolves in water to form a green solution, which turns 
brownish-yellow on the addition of hydrochloric acid and blackish- 
at 
