﻿DEPARTMENT OF AGRICULTURE BULS. 1376-1400 



Fag* 



Department Bulletin No. 1389. — Deterioration op Commercially 

 Packed Chlorinated Lime: 



Purpose of investigation 1 



Results of previous investigations 2 



Outline of investigation 4 



Results of investigation 7 



Discussion of results 14 



Summary 18 



Literature cited 19 



Department Bulletin No. 1390. — Chemistry and Analysis of the 

 Permitted Coal-Tar Food Dyes: 



Introduction 1 



Chemistry of permitted coal-tar food dyes 2 



Ponceau 3R 2 



Amaranth 4 



Ery throsine 5 



Orange I 6 



Naphthol yeUow S 7 



Tartrazine 8 



Yellow A B 9 



Yellow O B 10 



Guinea green B 10 



Light green S F yellowish ' 11 



Indigotine 12 



Methods of analysis of permitted coal-tar food dyes 13 



Reagents 13 



Preparation of sample 14 



Moisture 14 



Total water-insoluble matter 14 



Nonvolatile water-insoluble matter 15 



Sodium chloride 15 



Sodium sulphate 17 



Sulphated ash 18 



Heavy metals 19 



Iron, aluminum, calcium, and magnesium 19 



Arsenic 20 



Ether extractives 23 



Sulphur in color 24 



Color acid 24 



Pure coal-tar dye 26 



Matter insoluble in carbon tetrachloride 27 



Water extractives 27 



Melting point 27 



Lower sulphonated dyes 28 



Boiling point of i/'-cumidine from ponceau 3R 29 



Isomeric and similar dyes in amaranth 30 



Sodium iodide 30 



Iodide organically combined 30 



Total halogens 31 



Sodium carbonate in erythrosine 31 



Orange II and other subsidiary dyes in orange I 33 



Martius yeUow in naphthol yeUow S 33 



Total nitrogen 33 



Color by spectrophotometer 34 



Literature cited 35 



