5G8 ANNUAL* KEPORTS OP THE DEPARTMENT OF AGRICULTURE. 



chock analyses have been made for other bureau and branch hibora- 

 tories. 



Some 15 manufacturing plants were visited in the East and Middle 

 West and the various methods of manufacture and control carefully 

 observed. The information oathercd in this way, taken with the 

 evidence and data olfered at various hearings held at Washington and 

 at branch laboratories, indicated, as a rule, that the shortages or dis- 

 crepancies observed in the case of certain preparations were seldom, 

 if ever, due to willful intent on the part of the manufacturer, but 

 rather to a lax or faulty control, either in weighing and checking the 

 ingredients, in accounting for eventual wastage in granulation and 

 compression, or, finally, in handling the problem of lubrication. 



The investigation of various gums, as acacia, tragacanth, and In- 

 dian gum, was continued from the preceding year. A method was 

 evolved, thoroughly tested out, and published as Circular 94, on The 

 Volatile Acidity of Gum Tragacanth Compared with that of Indian 

 Gum, enabling one, in conjunction with the recognized qualitative 

 tests, to clearly differentiate between the tw^o products, whether alone 

 or in admixture. Methods have been perfected for the exact separa- 

 tion and estimation of the following combinations: Antipyrin, acet- 

 phenetidin, and codein; acetanilid, sodium salicylate, and codein; 

 antipyrin, caffein, and acetanilid; caffein, acetanilid, quinin, and 

 morphin. 



Cooperative work on headache and similar mixtures has been con- 

 tinued, as in the past, with the gratifying result that methods sug- 

 gested by this laboratory and submitted to outside workers for criti- 

 cism have invariably met with favorable reception. 



ESSENTIAL OILS. 



Forty-nine samples of essential oils have been examined, of which 

 46 were samples from interstate shipments. Nine cases of adultera- 

 tion and misbranding were reported. A number of samples for check 

 analysis were referred to this laboratorj^, as well as several products 

 of a miscellaneous character, including nitroglj'cerin tablets, castor 

 oil, glycerin, etc. A research on the composition of American spear- 

 mint oil has been conducted and the results published in Circular 96 

 of the Bureau of Chemistry. The study of oil of chenopodium, de- 

 signed to clear up the constitution of ascaridole, the medicinal con- 

 stituent of that oil, is yet in progress, and it is expected that the 

 results will soon be ready for publication. The study of methods for 

 the determination of various essential oil constituents, particularly 

 ketones, such as camphor, is being continued. 



The analysis of authentic samples of oil of wormwood has been 

 taken up with the purpose of establishing a standard of purity. 



PHARMACOLOGICAL INVESTIGATIONS AND BIOLOGICAL TESTING OF DRUGS. 



An exhaustive critical review of the literature on the action of drugs 

 under pathological conditions, with some experiments performed in 

 this laboratory, was published in Circular 81. 



The caffein investigations of the previous years have been contin- 

 ued. Two reports were made, one on the toxicity of caffein. Bulletin 

 148, the other on the elimination of caffein, Bulletin 157. Further 



