< R 
PERMITTED COAL-TAR FOOD DYES 11 
green on the addition of sodium hydroxide. Owing probably to the 
formation of the disodium salt, the aqueous solution is decolorized by 
an excess of sodium hydroxide. It is decolorized by a hot solution of 
alkalis or alkali carbonate. It is soluble in ethyl alcohol but less 
soluble in amyl alcohol. With concentrated sulphuric acid it forms 
a yellow solution, which when diluted with water turns first yellowish- 
red and then green. This dye has some properties which tend to 
‘cause it to separate from solution, particularly when a sweetened 
solution is carbonated, in the form of a green scum or foam. 
In 1889 the following patents for the preparation of guinea green 
B were issued: German patent 50,782 (1); British patent 7,550 (1); 
French patent 198,415 (1). 
The analytical data listed in Table 9 should be included in the 
foundation and supplemental affidavits (70). The methods of 
analysis and the purity specifications to which the dye must conform 
for certification are also indicated in the table. 
TABLE 9.—Specifications for guinea green B 
peer M M 
olerance inimum ethod of 
Component (ratio to pure| tolerance analysis 
coal-tar dye) 
Per cent Per cent Page 
JIC ea 5 ie eee ee eee 1050 (2 ae eee 14, 
Insoluble matter: 
Tyo $ ee ee eee eee 4s iy |e ee 15: 
_ (TIT GDG Se ee Se ee ee een Oe Sa yl = Se ae ae 15. 
ERMRMSECH I QUNIG et. 222 oe = Ve a Sas oe 402% 2: | Cree See e 15, 16, 
| TSTED GUUS) eS See a ee 1k 0 | Ses 18. 
(1 LEER GS fie * 2 Se ee ce ee eee Ly gt |e ee 18 
DST ied et Se ee eee ‘heoreticeal.| 2 = 18. 
VEC? TIGR Se ee See eee eee INone@s| 222-2 Sse 19. 
EFI ee ee ee eee D532 le Se ea 19. 
REST Se a ee eee ee oe euas | oa 19. 
SET. 5 ee a ee a ee ae eee ee 19. 
(Jb ae oee he ee ees SO a ts 5 19. 
_CPRELE SS 0 ee ee OOGIS Gees ee 21, 23. 
Ether extractives: 
aM Saw LEE ea Ee es ee ee ee rs (gee Pea et ee ABY. 
IPT os Se ee aS ee eee ee ee CL siete See et De ee a 23. 
JA GG a 3 oo at SS ee ee Ss ee ee ie (APR 5 ee eee coe 24. 
NTIS ew eo ee ee ee Ares" ai lE froma ston bomen 24, 
penne lattiaT En COlOR MM. a 2 2 2 Sh ee et ene Theoretieal. i222 = 24. 
UE PUG ee oe eee ae enn ee ae eee 79.4 | 25. 
0s SS Sa Ey aE 1 ee SSSI a pe no Eapeeesaee 82.0 | 26. 
} 
1 Although no limit is here defined, a statement of the percentage found by analysis must be incor- 
Porated in the foundation and supplemental affidavits (70). 
LIGHT GREEN S F YELLOWISH 
Light green S F yellowish (C,,H,,N,0,S,Na,), a triphenylmethane 
dye, differs from guinea green B in composition in that it contains one 
more sulphonic group (16). It is made by the condensation of ben- 
zylethylaniline with benzaldehyde, sulphonation of the product to the 
trisulphonic acid, oxidation of this, and conversion of the resulting 
compound into the mono- or disodium salt (59). As in the ease of 
guinea green B (p. 10), precautions are necessary with respect to 
purity of the intermediates, especially benzylethylaniline. The man- 
ufacture of this dye is more difficult than that of the other permitted 
dyes, owing to the production, by side reactions, of other organic 
substances, from which it is practically impossible to purify the fin- 
ished dye. In sulphonating, special care must be exercised to intro- 
