6 DEPARTMENT OF AGRICULTURE BULS. 1301-1325 



Page 

 Department Bulletin No. 1311. — The Chemical Composition of 

 Soil Colloids: 



Introduction 1 



Review of earlier work 2 



Ultimate chemical composition 2 



Compounds present 5 



Soils selected for a studj" of the colloidal material 8 



Field description 8 



Chemical composition 11 



Isolation and description of the colloidal material 13 



Ultimate chemical composition of the colloidal material 14 



Compositions of the colloidal materials of different soils 14 



Difference in composition of colloidal material, whole soil, and 



coarser particles 17 



Relation of sample analyzed to total colloidal matter in the soil.. 18 



Cause of variation in composition of the colloidal material 20 



Compounds present in collodial material 25 



Fragments of soil-forming minerals 25 



Attempted fractionation of colloidal material 27 



Action of solvents on colloidal material 28 



Compounds indicated by stoichiometrical calculation 34 



Conclusions regarding compounds present 37 



Summary 38 



Literature cited 39 



Department Bulletin No. 1312. — Loss of Nicotine From Nicotine 

 Dusts During Storage: 



Purpose of investigation 1 



Review of literature 2 



Outline of experiments 2 



Experimental results 3 



Volatility of nicotine sulphate solution and free nicotine solution 13 



Summary 14 



Literature cited 14 



Department Bulletin No. 1313. — Fumigation Against Grain 

 Weevils With Various Volatile Organic Compounds: 



Purpose of investigation 1 



Experimental procedure 2 



Effect of volatile organic compounds on weevils 3 



Relation between volatility and toxicity of fumigants 19 



Effect of fumigation on weevils in the presence of grain 24 



Fire hazard from fumigation 28 



Effect of fumigation on milled and baked products 34 



Additional fumigation tests with ethylacetate and carbon tetrachlo- 

 ride 35 



Effect of ethyl acetate-carbon tetrachloride fumigation on germina- 

 tion of seeds 38 



Summary 38 



Literature cited 39 



Department Bulletin No. 1314. — A Bibliography Relating to Soil 

 Alkalies. — Compiled With Special Reference to the Delete- 

 rious Action of Soil Alkalies, and Various Other Chemical 

 Agents on Cement and Concrete: 



Word and phrase abbreviations 1 



Abbreviations for names of periodicals cited 2 



I. Soil alkalinity 5 



Origin, distribution, physical, and chemical properties, and 



treatment 5 



II. Alkali soils salts 10 



Effects on mortar and concrete and measures for prevention 10 



III. Sea water 17 



Effects on mortar and concrete and measures for prevention; 



sea-water structures of concrete 17 



IV. Other injurious agents 26 



Effects of sewage, acids, oils, and various chemicals on mortar 



and concrete; measures for prevention 26 



