CONTENTS. 



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Department Bulletin 76. — Laboratory and Field Assay of Arsenical 



Dipping Fluids: Page. 



Introduction 1 



Laboratory methods 4 



Field methods of assay 10 



Field method for actual arsenious oxid 11 



Field method for " Total arsenic " 16 



The interpretation of results 17 



Department Bulletin 77.— Rocky Mountain Mine Timbers: 



Strength 1 



Consumption and durability 11 



Appendix 19 



Department Bulletin 78. — The So-called Tobacco Wireworm in Vir- 

 ginia: 



Introduction 1 



General habits and economic importance of the group to which the tobacco 



crambus belongs 2 



Economic importance of the tobacco crambus 3 



Origin and distribution . 4 



Seasonal history 4 



Description 5 



Life history 7 



Natural enemies 13 



Repression 14 



Bibliography 29 



Department Bulletin 79. — Research Studies on the Curing of Leaf 

 Tobacco: 



Introduction 1 



Nature of the curing process 2 



Loss in weight of dry matter in air curing when the leaf is primed 3 



Loss in weight of dry matter in air curing when the leaf is cured on the 



stalk- 7 



Effect of splitting the stalk on the -loss of weight in air curing 8 



Composition of cigar-wrapper leaf before and after curing 9 



Changes in composition of leaf tobacco in air curing 17 



Curing the leaves on the stalk compared with curing the picked leaves. . . 30 



Enzyms in tobacco curing 33 



Tobacco curing as affected by external conditions 36 



Summary 39 



Department Bulletin 80. — Effects of Varying Certain Cooking Condi- 

 tions in Producing Soda Pulp from Aspen: 



Purpose of experiments 1 



The soda process and its application 2 



Previous investigations 4 



Methods of conducting experiments 9 



Test materials used 14 



3 



